EGU General Assembly 2024  

While the deep Earth is not directly accessible, it can be explored by laboratory experiments under high-pressure and -temperature (P-T) combined with geophysical observations and geodynamical modeling. We conduct experiments using a laser-heated diamond-anvil cell (DAC) which can generate static high P-T beyond conditions at the center of the Earth. Combining such DAC experiments with in-situ X-ray observations at synchrotron sources and thermal/electrical conductivity measurements and ex-situ textural and chemical characterizations of recovered samples, we have been trying to uncover the structures, chemical compositions, physical properties, dynamics, and evolution of the deep Earth and planetary interiors. The lowermost part of the Earth’s mantle, sometimes called the D” layer, have been the most enigmatic region inside our planet, but the discovery of its main constituent crystals of post-perovskite dramatically improved our understanding of this mysterious layer. Recent hot debates on the core include its thermal conductivity and the mechanism of its convection that have sustained the planetary magnetic field since early history of the Earth. In addition, the Earth’s core is known to include substantial amounts of light elements such as sulfur, silicon, oxygen, carbon, and hydrogen, but its exact chemical composition has been highly controversial since Birch (1952). Hydrogen could be one of the important core light elements when considering that a large amount of water may have been delivered to the growing Earth and hydrogen is strongly siderophile (iron-loving) under high pressure. Nevertheless, the phase diagram and properties of iron hydrides are little known since hydrogen is least soluble into iron at ambient conditions. I will introduce these high-pressure studies on the deep mantle and core materials including our recent work on iron hydrides and discuss the possible ranges of Earth’s core composition.

How to cite: Hirose, K.: Exploring the deep Earth and planetary interiors by high-pressure experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1663, https://doi.org/10.5194/egusphere-egu24-1663, 2024.

The Moon is thought to have been covered initially by a deep magma ocean, its gradual solidification leading to the formation of the aluminium-rich plagioclase-bearing highland crust. We performed the first high-pressure, high-temperature experimental study of the mineralogical and geochemical evolution accompanying the full solidification of a lunar magma ocean (LMO) and provide new constraints on the presence of water in the early lunar interior. In a dry Moon, plagioclase appears after 68 per cent solidification and yields a crust with a thickness of ~68km¹, well above the lunar crustal thickness suggested by recent GRAIL mission gravitational data (34–43 km). Water-bearing experiments show a delay in the start and lowering of the volume of plagioclase formed during LMO crystallization, as observed previously for terrestrial magma. Using crustal thickness as a hygrometer we conclude that at least ~800 ppm water was present in the Moon at the time of LMO crystallization, indicating the Earth-Moon system was water-rich from the start^2,3.

Water does not only have remarkable effects on early LMO evolution, but also on the properties of Earth’s mantle rocks, however, how and how much transporting water into the deep Earth is still debated due to high mantle temperatures. Subduction of oceanic lithosphere transports surface H₂O into the mantle. Recent studies proved that stishovite and post-stishovites as high-pressure phases of SiO₂ have the potential to carry weight percent levels of water into the Earth’s interior along the geotherm of the subducting oceanic crust⁴. Regression of our experimental data indicates an H₂O storage capacity in stishovite of ~3.5 wt% in the transition zone and shallow lower mantle, decreasing to about 0.8 wt% at the base of the mantle⁵. As slabs subducted to the deepmost mantle, dehydration of these dense hydrous silica phases (DHS) can potentially change physicochemical properties of the Earth’s mantle by reducing melting point, forming new high-pressure phases and enhancing the oxygen fugacity heterogeneity of lower mantle⁶.

References:

[1] Lin Y., Tronche E. J., Steenstra E. S., and van Westrenen W. Experimental constraints on the solidification of a nominally dry lunar magma ocean. Earth Planet. Sci. Lett. 471, 104–116 (2017).

[2] Lin Y., Tronche E. J., Steenstra E. S., and van Westrenen W. Evidence for an early wet Moon from experimental crystallization of the lunar magma ocean. Nat. Geosci. 10, 14–18 (2017).

[3] Lin Y., Hui H., Xia X., Shang S., and van Westrenen W. Experimental constraints on the solidification of a hydrous lunar magma ocean. Meteorit. Planet. Sci. 55, 207–230 (2020).

[4] Lin Y., Hu Q., Meng Y., Walter M. and Mao H.-K. Evidence for the stability of ultrahydrous stishovite in Earth’s lower mantle. Proc. Natl. Acad. Sci. U. S. A. 117, 184–189 (2020).

[5] Lin Y et al. Hydrous SiO₂ in subducted oceanic crust and H₂O transport to the core-mantle boundary. Earth Planet. Sci. Lett. 594, 117708 (2022).

[6] Lin Y. and Mao H. K. Dense hydrous silica carrying water to the deep Earth and promotion of oxygen fugacity heterogeneity. Matter Radiat. Extremes 7, 068101 (2022).

How to cite: Lin, Y.: Effects of water on the evolution of the Early Moon and deep Earth investigated by experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4803, https://doi.org/10.5194/egusphere-egu24-4803, 2024.

Lake Tziscao is one of the water bodies belonging to Lagunas de Montebello National Park, located in the south-southeastern part of the state of Chiapas, Mexico. Its importance lies in its great tourist activity due to its size and nearby human settlement, which is why there are numerous anthropogenic factors that promote the transformation of natural areas within it.

In this work, PHREEQC software was used to perform inverse hydrogeochemical modeling, with which the predominant hydrogeochemical processes of the site were identified and estimated using 20 sampling points distributed along Lake Tziscao.

Prior to the execution of the model, a statistical analysis, simplification and graphic representation of samples, as well as a site analysis were carried out, whose comparison results coincide with the presence of calcic-magnesic bicarbonate type waters, suggesting the feasibility of the proposed model.

Modeling results indicate that the main processes present in the water-rock interaction in the area are: hydration of anhydrite and subsequent dissolution-precipitation of gypsum in large proportion, minimal transfer or equilibrium in carbonate minerals and halides such as calcite, dolomite, sylvite and halite, nonetheless, the concentrations of elements such as nitrogen and phosphorus within the water body suggest anthropogenic pollution sources, while the relatively low salinity indicates that the waters are poorly evolved or have been transported to a lesser extent.

How to cite: González Herrera, C. R. and García Villanueva, L. A.: Identification of hydrogeochemical processes through inverse modeling in PHREEQC in Lake Tziscao, belonging to the Montebello lagoon system in Chiapas, Mexico., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-26, https://doi.org/10.5194/egusphere-egu24-26, 2024.

Geochemical sampling has limitations due to budget constraints and restricted access to certain areas. This results in some regions being unsampled, making it difficult to generate comprehensive geochemical anomaly maps and distinguish between background values and anomalies. To address this, different interpolation models have been developed, such as inverse distance weighting (IDW) and kriging techniques. However, both IDW and kriging only consider the horizontal distance between samples and ignore elevation changes, which is important in real-world terrains. This effect is most pronounced in mountainous terrains. To address this, we propose a new interpolation technique called Inverse Radius Weighting (IRW). IRW factors in both horizontal distance and elevation changes between sample pairs, resulting in more accurate predictions. Detailed elevation data is available for the entire globe in the form of digital elevation maps from the Shuttle Radar Topography Mission (SRTM) and other sources. In this research, both IDW and IRW models were applied to soil samples in Cyprus. A comparative analysis between IDW and IRW models showed that IRW gives more accurate predictions, especially in terrains with complex morphologies. IRW's ability to account for topographical influences makes it the preferred choice in such scenarios.

How to cite: Sadeghi, B., Morrison, S., Eleish, A., and Klump, J.: Inverse Radius Weighting (IRW) interpolation model: A new interpolation considering morphology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1348, https://doi.org/10.5194/egusphere-egu24-1348, 2024.

In regional or local scale geochemical mapping, the choice of sampling media and analytical methods will be influenced by the source, form, mobility and spatial distribution of elements being mapped. For environmental monitoring and mineral exploration there are potential advantages in using plant organs rather than regolith materials as the sampling media, including the capacity of plants to sample large volumes of underlying regolith and the averaging of their biogeochemical composition over timeframes extending from months to years. The limited use of plant organs in geochemical mapping relates partly to perceived complicating factors such as variability between plant species, seasonal variability in some plant organs and analytical costs.

Needle samples from over 4,000 cypress pines (C. glaucophylla) in the highly mineralised Cobar Basin in central New South Wales have been analysed by both ICPMS and pXRF. The study spanned regional mapping using samples collected adjacent to roads and tracks, and detailed grids and traverses across 36 mineral prospects and deposits. For various major and trace elements, there is strong correlation between results obtained by total digestion ICPMS and by portable XRF, including direct pXRF analysis of unprocessed samples in the field.

There are distinct lithological influences on variation in the background values for various elements, including Au and Pb, noting that the majority of mineral deposits are structurally hosted within the Devonian sandstone and siltstones regionally intruded by felsic intrusives. There is an extensive zone of elevated base and precious metal values in the needles between the Peak Au mine site and the city of Cobar which was the focus of mineral processing for many decades. Highly elevated values for Ag, Au, Pb, Zn, Ni, Co, W and/or REE occur above known mineral deposits, depending on deposit style, and commonly display more consistent geochemical spatial patterns than in regolith samples. Pines in general typically restrict uptake of Cu in the needles to within the range of 3–12 ppm due to its function as an important trace nutrient.

How to cite: Schifano, J., Cohen, D., and Rutherford, N.: Pining for an Anomaly: Exploration and environmental assessments using regional and local scale biogeochemical patterns in the Cobar Region, Australia., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1404, https://doi.org/10.5194/egusphere-egu24-1404, 2024.

The nuclear forensics is one of the pillars in the architecture of nuclear security, as a response to criminal acts and illicit trafficking involving nuclear materials or other radioactive materials. ENEA is participating in international table-top exercises organized by the Nuclear Forensics International Technical Working Group (ITWG), a community whose aim is to advance the scientific discipline of nuclear forensics supporting the development of national capabilities. The “Galaxy Serpent” is a set of virtual international web-based exercises, focused on the development of National Nuclear Forensic Libraries (NNFLs). The aim is to increase national awareness of the technical challenges associated with the development of a National Nuclear Forensic Library (NNFL) and how it can be a valuable support for investigating crimes and/or illicit activities involving nuclear or radioactive materials.

The ENEA CBRN team participated in the Galaxy Serpent exercise, version 3, focused on the investigation on imported uranium ore concentrate materials. The used approach, the tools and the main outcomes will be presented. The scenario was dealing with the interception of a transport vehicle attempting to leave the country carrying radioactive materials out of regulatory control (MORC). In fact, further inspection revealed geological sources within some labelled containers and the isotopic analysis performed on these materials determined the sources to be uranium ore concentrate (UOC). The ENEA CBRN team was tasked to check whether this material was consistent with the material used within its country. The assessments have been carried out using Rare Earth Element (REE) patterns as main fingerprint of the geochemical affinity classes. REEs can be used to verify the origin of the samples and some process they have experienced as they are water insoluble and present in very low concentration in water, so they really reflect the original chemistry of the source. In addition, variations in their concentration could be indicative of technological processes aimed at the recovery of some elements that have different high technology applications. The use of statistical tools for the extrapolation of forensic information are presented and discussed.

The exercise had the dual purpose of testing, on the one hand the team’s skill level and the type of tools necessary for a response in the mitigation of chemical, biological, radiological, nuclear and risks (CBRN), and on the other hand, to prepare tools and procedures that may also involve other actors at national level, in particular in response to radiological risk.

How to cite: Telloli, C., Ottaviano, G., Rocchi, F., Padoani, F., and Rizzo, A.: Nuclear Forensic of Uranium Ore Materials out of Regulatory Control: The Galaxy Serpent exercise v3, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1715, https://doi.org/10.5194/egusphere-egu24-1715, 2024.

Anthropogenic Pb originated from leaded petrol and high temperature industrial activities is still a major contamination issue to various compartments in the urban environment, including soil and road dust. Human exposure to Pb near Pb-contaminated areas involves incidental ingestion of soil and road dust and inhalation of resuspended solid particles. Volos is a medium-sized industrialized city, located in central Greece, surrounded by steel and cement factories. The geochemical reactivity, fractionation and bioaccessibility (both oral and inhalable) of Pb in selected soil (n=10) and road dust (n=10) samples were investigated through a variety of laboratory chemical methods comprising the dilute HNO₃ extraction, the BCR sequential extraction procedure, the simple bioaccessibility extraction test (SBET) and a simulated lung fluid (SLF solution, artificially lysosomal fluid). In addition, the Pb isotopic composition of both total and bioaccessible Pb was determined to identify the Pb sources and examine potential differences of Pb solubilization in terms of its origin when interacting with simulated human stomach and lung fluids.

Lead was found in highly reactive forms in both road dust and soil (medians 83% and 69% of total contents, respectively). The majority of Pb was found to be associated with the sum of the acid soluble (F1), reducible (F2) and oxidizable (F3) fractions (median 72% of total contents for both soil and road dust), indicating that Pb has a high remobilization potential from the solid matrix. The oral bioaccessibility (%) of Pb was higher than the inhalation one (medians 49% and 37% of the total content), respectively), highlighting the soil and dust ingestion as the primary route of Pb exposure. The isotopic analyses of total Pb in soil and road dust (²⁰⁶Pb/²⁰⁷Pb = 1.144 to 1.192) suggest that the predominant anthropogenic Pb source is industrial Pb from the steel plant, with minor contributions of Pb derived from vehicular emissions. Interestingly, we found significant differences in the isotopic ratios between total and bioaccessible Pb (²⁰⁶Pb/²⁰⁷Pb = 1.130 to 1.152), demonstrating that Pb solubilized by the simulated gastric and lung extractions is principally anthropogenic. High Pb bioaccessibilities (%) accompanied a shift towards lower ²⁰⁶Pb/²⁰⁷Pb ratios. Moreover, ²⁰⁶Pb/²⁰⁷Pb ratios of both total and bioaccessible Pb exhibited significantly negative correlations with Pb reactive fractions (%), showing that natural Pb is linked to low Pb release from the soil and road dust matrix. Overall, Pb isotopes provide deep insights into the connection between Pb bioaccessibility and reactivity with Pb sources in soil and road dust from industrial environments.

References

Kelepertzis, E., Chrastný, V., Botsou, F., Sigala, E., Kypritidou, Z., Komárek, M., Skordas, K., Argyraki, A. 2021. Tracing the sources of bioaccessible metal(loids) in urban environments: A multidisciplinary approach. Science of the Total Environment 771: 144827.

How to cite: Kelepertzis, E., Kypritidou, Z., Chrastný, V., and Komárek, M.: Geochemical occurrence of Pb in soil and road dust from an industrialized urban environment: Fractionation, bioaccessibility and isotopic composition , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1834, https://doi.org/10.5194/egusphere-egu24-1834, 2024.

Provenance studies of flint artefacts provide important means for interpreting raw material procurement strategies, which testify to the level of expertise and environmental knowledge of prehistoric people. Due to its importance, different approaches and methods have been used in order to address this topic, which often makes it difficult to compare different studies. During the recent years we have been exploring the potential of bulk rock composition of flint measured using inductively coupled mass-spectrometry (ICP-MS) for provenance studies. Through the systematic sampling of flint from all across Israel (now archived at the Geological Survey of Israel, as part of the developing national flint collection) and the investigation of a large suite of trace elements, we have been developing a robust approach for determining the provenance of flint. By sampling several specimens from each locality and measuring a large array of elements, we additionally address the variability of compositional data in natural rock sources, and develop a statistical framework for evaluating the uncertainty involved in the provenancing of flint. These developments have been applied in recent case studies in key archaeological sites, and shed new light on the old question of flint provenance in prehistory.

How to cite: Ben Dor, Y., Finkel, M., Sharon, G., Tirosh, O., Bar, O., and Ben-Yosef, E.: Recent advances in flint provenance studies in Israel developed by combining geochemical and statistical perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2817, https://doi.org/10.5194/egusphere-egu24-2817, 2024.

Local glaciers and ice caps in the Northern Hemisphere and the Greenland Ice Sheet (GrIS) have recently been suggested to be important parts of the Arctic mercury (Hg) budget. Based on ice-core data, the recently estimated total glacial Hg pool is approximately 2,400 tons, approximately 97% of which is in Greenland¹. With Hg concentrations in pre-industrial ice being significantly lower than in ice formed during the 19th and 20th centuries, the dominating source of glacial Hg and input to the Arctic Hg budget is ascribed to long-range transport of anthropogenic Hg emissions².

Alarming concentrations of Hg in meltwater from the western margin of the GrIS were recently reported³. With Hg concentrations reported as being 100 - 1000 times higher than what is known for other freshwater systems of Greenland and a postulated increase in Hg export to downstream environment following climate warming and asserted global importance of Hg fluxes from the GrIS, these extraordinary concentrations and conclusions calls for independent verification.

In our current study⁴, we expand the sampling of subglacial meltwater from 21 representative outlets at GrIS in 2021 and 2022 to get a better scientific basis for conclusions on the magnitude of glacial Hg sources in Greenland. Results from our study consistently show that both total and dissolved Hg concentrations in glacial meltwater over space and time are very low (generally <10 pM) and that an extremely elevated Hg concentration range (up to 4000 pM recently reported³) cannot be reproduced.

In contrast to what was previously reported³, we find that meltwater from below the GrIS is very low in Hg; has minor implications for the global Hg budget and pose only a very limited risk for local communities and the natural environment of Greenland.

References:

• A. Dastoor, et al. (2022), Arctic Mercury Cycling. Nature Reviews Earth & Environment 3, 270–286 (2022). https://doi.org/10.1038/s43017-022-00269-w.
• AMAP. AMAP Assessment 2021: Mercury in the Arctic. Arctic Monitoring and Assessment Programme (AMAP),1- 324.
• J. R. Hawkings et al (2021) Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet. Nature Geoscience 14, 496–502 (2021). https://doi.org/10.1038/s41561-021-00753-w.
• Jørgensen et al (2024) Large mercury release from the Greenland Ice Sheet invalidated. Science Advances, in press.

How to cite: Jørgensen, C. J., Søndergaard, J., Larsen, M. M., Kjeldsen, K. K., Rosa, D., Sapper, S. E., Heimbürger-Boavida, L.-E., Kohler, S. G., Wang, F., Gao, Z., Armstrong, D., and Albers, C. N.: No evidence for large mercury release from the Greenland Ice Sheet: recent conclusions on global mercury budget invalidated. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4005, https://doi.org/10.5194/egusphere-egu24-4005, 2024.

The study of ancient aqueducts shows us how past societies used water resources such as rivers, lakes, springs and groundwater. Such resources were tested for their quality, captured, sometimes diverted or abandoned, or supported by a new source. The efficient management of ancient water supply systems was adapted to societal needs, to the chosen environment and to change in climate and population dynamics, similar to factors shaping our modern water management. The in-situ carbonate deposits of ancient water supply systems reflect characteristics of the water resources and aquifers used, and therefore constitute an archive with considerable research potential, particularly for better understanding of ancient water management, palaeo-environment, and water scarcity.

            Ancient aqueducts were long-lived structures, with recorded operation periods of up to 800 years such as the more than 400 km long Valens aqueduct of Constantinople. However, carbonate sequences are often shorter because of cleaning. The Valens aqueduct has a double channel to allow cleaning without interruption of the water supply, and shows only 27 years of carbonate deposits. A carbonate sequence of 250 years is documented for the ancient city of Nemausus, which correlates with the actual documented years of operation. This is because some aqueducts were built wide enough to allow smooth operation without being cleaned of carbonate for most of their length. The aqueduct of Arelate was modified by reallocation of branches and expansion, probably in response to increasing and changing demand of water. In at least 50 years of carbonate stratigraphy, this aqueduct shows periodic variations in the aquifer.

            As the focus of this paper we discuss the Roman aqueduct of Divona, which shows evidence of regular cleaning, repairs, modifications and even timing of maintenance, captured in aqueduct carbonate. The d¹⁸O profile of the carbonate stratigraphy shows a cyclicity that is inferred to reflect annual water temperature variations in the channel. This cyclicity was used to determine the timing of maintenance. The aqueduct operated for centuries but the preserved profile shows 88 years of operation, interrupted by two plaster repair events, representing time breaks in water supply of at least several months. Not less than 14 carbonate removal events were recognized, which took place in fall, spring, or winter but never in summer, with an interval of 1 to 5 years. Carbonate removal from channels was done rapidly, in less than one month, since stable isotope cycles show no indication of a long-term interruption in the water supply. The last maintenance was done only three years before the final abandonment of the water supply, showing that continued operation of the aqueduct was planned but was not fulfilled. This micro-story shows how a historical water management operated and adapted to water scarcity and population growth and decline, similar to modern days. Frequent cleaning of aqueduct carbonate and repairs are examples of what we call today “sustainable” water management.  

Ancient aqueducts carbonates are models to study aspects of past water management and adaptations to crisis, and provide a vision for the future of water availability and climate change.

How to cite: Sürmelihindi, G. and Passchier, C.: Lessons learned from the maintenance of ancient aqueducts through their carbonate archives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4708, https://doi.org/10.5194/egusphere-egu24-4708, 2024.

The project focuses on a provenance study carried out on Zeus/Owl bronze coins, coming from the Greek colony of Velia in southern Italy, and dating back to the 3rd century BC. Chemical elemental composition and lead isotope analyses were carried out at the Laboratori Nazionali del Gran Sasso-INFN by using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) techniques. Lead isotope ratios of the coin samples were compared with data from various ore deposits in the main Mediterranean areas documented in existing literature. Additionally, the elemental composition was examined to establish distinctive geological characteristics aiding in identifying the provenance sources of the studied coins. The majority of the coins exhibited an isotope signature of the lead, that makes up the alloy, overlapping with multiple clusters in the Aegean Greece area (Syros, Kea, Antiparos, Serifos and Sifnos) and the Spain South-East area (Cartagena-Mazarron and Almeria). Six coins displayed an uncertain provenance, suggesting the possibility of mixing and/or metal recycling. Notably, one coin demonstrated overlap with both Spain South-East and Tuscany clusters, indicating a shared provenance probability. Regarding the results of the elemental analysis, the main elements that make up the coins alloy are copper, lead and tin. The Pb content ranges considerably from a minimum of 0.5% to a maximum of 24.9%, while the concentration of Cu ranges from a minimum of 73.3% to a maximum of 93.5% and that of Sn ranges between 1.7% and 10.3%. This information contributes to the reconstruction of historical trade routes, enhancing our understanding of the dynamics of metal supply and socio-economic relationships in Velia.

Keywords: Provenance study; Isotopes; Ancient Coins; Ore Deposit; TIMS

How to cite: Ercoles, I., Castorina, F., Nisi, S., Carbone, F., Pardini, G., and Trincherini, P. R.: Provenance Analysis of Zeus/Owl bronze Coins from Velia: A Comprehensive Study using ICP-MS and TIMS Techniques, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5724, https://doi.org/10.5194/egusphere-egu24-5724, 2024.

Consumers' growing attention on food composition, quality and origin has sparked a renewed interest in food traceability. The use of isotopic markers of territoriality helps emphasize the connection between agricultural products and their specific geographical area of origin, linked both to the soil-to-plant continuity of elemental composition and to contribution from airborne substances assimilated directly by the shoot. Asparago di Altedo PGI is an exclusive product of the Eastern area of Emilia-Romagna region, between Via Emilia and the Adriatic coast. Sandy-based territories favour the emergence of asparagus turions but include significant variations from sandy-clayey loam soils to lean sandy soils, forming a gradient from the inland to the coast. This research aims to detect a potential asparagus diversification driven by soil and environmental characteristics in the province of Ferrara, useful for further defining the product's typicality with respect to the area of origin. For the selected fields (Malborghetto, Mezzano, Bosco Mesola, Mesola, Lagosanto, Volania, Valli Basse), soil and plant sampling took place from May to the early days of June 2023. As an outgroup, samples of common green asparagus cultivated in Abruzzo region (Central Italy) were collected. The turions were transported to the laboratory for analyses of the fast chlorophyll fluorescence induction, a non-destructive near-instantaneous method for physiological plant assessment. Subsequently, soil and asparagus samples were dried and powdered for isotopic analyses. Soil diversification was characterized through pH and chemical analysis of major and trace elements using X-ray fluorescence. To assess the influence of the environment/soil on asparagus, δ¹³C and δ¹⁵N isotopic ratios, as well as the C/N ratio, were analyzed on soils and plants using an elemental analyzer associated with an IRMS spectrometer. PCA analysis showed that the soils could be distinguished based on geochemical factors and, for some fields, even at a resolution of a few tens of kilometres. For instance, the abundance of Na₂O separated the coastal fields from those of inland, and the soil samples of the Malborghetto field stood out from the others due to a higher concentration of certain heavy metals (Cr, Ni, Pb). Soil diversification was also attributable to anthropic interventions in the reclamation of the lagoon areas in some parts of the Ferrara province. An interesting correspondence was found between soil diversity and chlorophyll fluorometric parameters. In particular, although the photosynthetic functionality of the plants was very good in all fields, it was possible to distinguish the asparagus samples based on their origin: for example, the most performing asparagus was from Mesola regardless of the cultivar. Work is still in progress to get a more complete picture of the soil-to-plant continuity in relation to the environmental characteristics of the examined fields.

How to cite: Marrocchino, E., Aliprandi, E., Martina, A., Tassinari, R., and Ferroni, L.: Isotopic and functional markers for the assessment of territoriality: the case study of Asparago di Altedo PGI in the province of Ferrara (NE Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6499, https://doi.org/10.5194/egusphere-egu24-6499, 2024.

Our research presents a thorough analysis of climatic and environmental transformations in the Central Dnieper Basin (CDB) during the Middle and Late Pleistocene. It focuses on the study of glacial features left by the Dnieper lobe of the Saalian ice sheet and the co-occurring loess covers, as expressions of Pleistocene climatic fluctuations and landscape changes.
The research includes a detailed analysis of loess distribution, revealing a clear contrast between isolated loess patches in the northern lowlands and a continuous, thick loess cover in the south, especially from the latitude of Kyiv. These covers contain well-developed paleosols, reflecting interglacial changes, which form the basis for deep chronostratigraphic correlations on a regional and supra-regional scale. A key element of the study is resolving unresolved stratigraphic issues of the Pleistocene in Ukraine, with particular emphasis on the chronostratigraphic position of loess and paleosol units in the context of global climatic stages.
The main aim of the research is to identify local environmental influences on recorded Quaternary events following the deglaciation of the Dnieper lobe, to reconstruct the interactions between landscape changes post-glacial retreat and aeolian systems, and to establish a comprehensive and reliable stratigraphy for the Quaternary deposits of the Central Dnieper area. The methodology includes the application of a wide range of multidisciplinary techniques, including detailed grain size distribution and chemical composition analysis, advanced colourimetric measurements, paleomagnetic studies and luminescence dating. The research is based on original and older (palynological) studies on the Pleistocene, highlighting the importance of loess-palaeosol sequences in reconstructing the environmental history of the region.
The CDB, located at the juncture of the Dnieper Upland and Dnieper Lowland, provides unique insights into glacial, fluvial, and loess accumulation. Research includes detailed lithological and pedological sediment characterizations at key geological sites. Results of laboratory analysis clarify transport, deposition, and transformation processes of glacial and aeolian materials, indicating significant loess autochthony. Thermal and precipitation data from pollen analysis of mineral-soil sediments highlight the climatic condition's spatial and temporal variability in the CDB. Biome analysis shows varied landscape mosaics in each cycle, with no total deforestation in climatic pessima or complete afforestation in interglacial optima. These findings offer new insights into the CDB's complex Pleistocene stratigraphy, evidencing the last ice sheet's advance in the Dnieper valley during MIS8, and its link to ana- and kataglacial L3 loess sedimentation phases. They also emphasize the local variability and diversity of soil cover evolution and transformation after the glacial retreat, influenced by the post-glacial topography.
Our research significantly broadens the understanding of environmental changes in the Middle and Late Pleistocene in the CDB, contributing to the development of stratigraphic models and paleoenvironmental reconstructions on both regional and global scales.
Research carried out as part of the grant of National Science Centre, Poland as the project no. 2018/31/B/ST10/01507 entitled “Global, regional and local factors determining the palaeoclimatic and palaeoenvironmental record in the Ukrainian loess-soil sequences along the Dnieper River Valley – from the proximal areas to the distal periglacial zone”.

How to cite: Łanczont, M., Mroczek, P., Komar, M., Nawrocki, J., and Standzikowski, K.: Deciphering Middle-Late Pleistocene environmental changes: a multidisciplinary approach to Middle Dnieper loess-palaeosol sequences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8265, https://doi.org/10.5194/egusphere-egu24-8265, 2024.

Transition from fossil fuels to renewable energies is key to reduce human CO2 emissions, in order to cope global warming. As well as the need of technological progress, this raise the needs for metal resources. Some commodities are likely to experience very strong growth of their demand over the coming decades such as Lithium (Li), Aluminum (Al), Cobalt (Co), Nickel (Ni), Copper (Cu), and Rare Earth Elements (“REE”), due to their uses in “green” energy technologies.

The EU-funded “MADITRACE” project aim for the development of traceability methods and certification systems for four critical raw material (CMR): lithium, graphite, cobalt and REEs, in order to integrate sustainable provenance of materials into a Digital Product Passport (DPP) for batteries and vehicles. In the particular case of lithium, a previous study has shown that the deposit type -‘Hard rock’ or Salar- origin of a lithium material can be tracked through the supply chain up to the battery using lithium isotopic analysis¹. Nevertheless, some processes can affect this signature. In addition, these analyses requires high-cost instruments and are time-consuming. In order to verify in the future the provenance of a batch of raw material, traceability tools must be resilient to processes and mixing. They should also be more democratized and faster to set-up.

In this regard, the project focuses on the development of the combination of rapid and easy-to-use on-site analysis for routine screening as well as laboratory verification in case of anomalies during the provenance verification of a lithium product. This relies on conventional geo-physico-chemical analysis such as mineralogy, major and trace element compositions, as well as isotopic analysis. The methods investigated includes hyperspectral spectroscopy, IR spectroscopy, LUXREM (XRF-XRD coupling, in development) as well as conventional X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD), Laser Induced Breakdown Spectroscopy (LIBS), (Laser Ablation) Inductively Coupled Plasma Mass Spectrometry ((LA)-QQQ-ICP-MS), (Laser Ablation)  Multi-Collector Inductively Coupled Plasma Mass Spectrometry ((LA)-MC-ICP-MS) and Thermal Ionization Mass Spectrometry (TIMS).

• Desaulty, A. M. et al. Tracing the origin of lithium in Li-ion batteries using lithium isotopes. Nat Commun 13, (2022).

How to cite: Moradell-Casellas, A., Desaulty, A.-M., Monfort-Climent, D., Perret, S., Guerrot, C., Kloppmann, W., Lafaurie, N., Gilardi, N., Delchini, S., Maubec, N., and dezes, M.: Lithium geochemical traceability: development of a multi-criteria approach using on-site and laboratory technologies for the implementation of a battery digital product passeport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9041, https://doi.org/10.5194/egusphere-egu24-9041, 2024.

The Almadén mercury mining district, located in South-central Spain, has been the most important producer of this element worldwide, until the cessation of exploitations in year 2003. The environmental consequence of this activity affects an area of some 250 km², coincident both with a geological structure (the Almadén syncline) and a river basin (the Valdeazogues river and tributaries). The old cinnabar (HgS) mines and mineral showings are scattered in the syncline and in the basin, favouring a wide distribution of the elements in the soils and sediments, as reported by previous publications from this research group and partners.

Crayfish (Procambarus clarkii) is an exotic river crab, with has replaced the autochthonous one  (Austropotamobius pallipes) due to its voracity. It is very common all along the Valdeazogues river and tributaries, and it is captured and consumed by local population in summertime, when it is easily captured in the ‘tablas’, water accumulated in river pods during the cessation of water running due the stational drought. Preliminary data on the Hg contents in this species, obtained in year 2005 reach up to 9,060 ng g^-1 (in muscle) and 26,150 ng g^-1 (in hepatopancreas), according to some previous publications of this research group.

In this communication we present new data on this issue, obtained during the year 2022 along the Valdeazogues river and in some of its tributaries. In this research, 330 crayfish (sizes between 7 and 12 mm) were captured from upstream of the El Entredicho open pit mine to downstream of the confluence with the Guadalmez river (about 36.3 km), as well as the Los Álamos stream, and the Azogado stream, both tributaries of the Valdeazogues. All specimens were analysed by Zeeman effect atomic absorption spectrometry.

The overall results showed maximum values of 3,567 ng g^-1 of total Hg in muscle tissue, with a mean value for the district of 1,617 ± 920 ng g^-1. In hepatopancreas which is an organ of the digestive tract with functions of absorption and storage of nutrients, as well as synthesis of digestive enzymes, the maximum value is very similar: a maximum of 3,590 ng g^-1, while the mean is slightly lower, 1,025 ± 1,028 ng g^-1. For the whole population, the relationship of Hg content in muscle tissue and hepatopancreas with size is not appreciable, probably because they are organisms of fast grown, and there is no general relationship between age and size. On the other hand, there is a relationship between Hg in hepatopancreas and salts contents and total Hg concentration in the nearby sediments.

How to cite: Higueras, P., Barquero, J. I., Bakale, F., Esbrí, J. M., and García Ordiales, E.: Bioaccumulation of mercury in muscle tissue and hepatopancreas in red crayfish (Procambarus clarkii) in a transect of the Valdeazogues river and tributaries, Almadén Hg mining district, south central Spain. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9369, https://doi.org/10.5194/egusphere-egu24-9369, 2024.

Asturias, located in northern Spain, is a region with a rich history of mining and metallurgical activities intertwined with coal and metals. The Hg-mining district situated in the centre of this region was the Spain’s second-largest Hg manufacturer from 60s to 70s. Several areas were affected by the presence of Hg, specifically in the “El Terronal” mine, which stands out as one of the most affected areas, primarily due to mining and subsequent pyrometallurgical processing.

A pilot-scale remediation using nanoscale zero-valent iron (nZVI) was conducted on a soil plot with a Hg concentration of 1500 mg/kg in “El Terronal”. The nZVI proved to be an exceptional amendment for Hg immobilization, revealing an 86% reduction in Hg mobility within 72 hours of applying the nZVI, sustained over a period of 32 months. Nevertheless, the long-term effects and mechanisms of Hg remediation remain not fully understood. In light of this, the present work focused on elucidating Hg speciation changes 6 years after the application of nZVI in a Hg-polluted soil under field conditions.

Soil samples were taken from both the treated plot and an adjacent untreated plot before nZVI application and after 6 years. Initially, a simplified USEPA Method 3200, involving sequential extraction, was used to evaluate the Hg mobility. Subsequently, the identification of Hg species was conducted using a mercury temperature programmed desorption (HgTPD) device. Based on preliminary results, the reference database for mercury compounds in this work were HgO, cinnabar (HgS), metacinnabar (HgS), HgCl₂, HgSO₄, corderoite (Hg₃S₂Cl₂), Hg complexed to humic acid, and Hg adsorbed to goethite. Furthermore, X-ray absorption spectroscopy was employed to complement the study of mercury speciation. In this regard, soils and patterns were prepared as pellets from finely ground and homogenized powder. The Hg L_III-edge spectra XANES were collected in transmission and fluorescence modes at 70-80 K on CLAESS beamline (ALBA synchrotron).

The concentration of Hg in the mobile fraction was below detection limit in both samples, treated and untreated soils. However, a decrease on the semi-mobile fraction was found from 57% to 39% in the treated soil with nZVI respect to the untreated soil. This result is in accordance with the Hg immobilization reported at the beginning of the field remediation. With respect to HgTPD, the Hg species identified corresponds to Hg bound to S. On the other hand, the data treatment by linear combination fits of the Hg L_III-edge spectra XANES demonstrated that the Hg solid speciation in the treated and untreated soil samples is similar, mainly dominated by cinnabar, metacinnabar, and Hg adsorbed to goethite. This result, may indicate that the Hg mobile is associated to a minor phase, not quantifiable, or to a Hg immobilization from all phases without preference.

In summary, the mobility of Hg is linked to only a minor fraction of the total concentration of these elements in the soil, with this metal being predominantly associated with cinnabar, metacinnabar and goethite. Consequently, the complete observation of the effects of immobilization processes on Hg speciation was hindered by resolution limitations.

How to cite: Baragaño, D., López-Toyos, L., Simonelli, L., López-Antón, M. A., and Ratié, G.: Remediation of mercury-polluted soil in a mining area using nanoscale zero-valent iron, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9549, https://doi.org/10.5194/egusphere-egu24-9549, 2024.

A key aspect for the evaluation of environmental and health risk associated with mercury (Hg) contamination is the assessment of its speciation, which can influence the mobility and bioavailability of this element in the environment. The evaluation of Hg speciation in soils and sediments of contaminated sites is commonly based on selective sequential extraction (SSE) methods, which, however, have certain disadvantages: they do not allow for a specific removal of Hg species, are generally time-consuming and characterised by a low reproducibility. An easy-to-use alternative to SSE may be represented by thermo-desorption (TD) technique, where different Hg species can be identified according to their specific release temperature during a gradual heating. The aim of this study was to evaluate the potential application of TD for the risk assessment associated with Hg occurrence in alluvial soils at some sites in the Friuli-Venezia Giulia Region (NE Italy) affected by past Hg inputs related to mining and, to a lesser extent, industrial activities. At each site, surface and deep soil samples (n≥12) were collected and analysed for total Hg concentration and Hg speciation through TD. Speciation analyses were performed by means of a Hg atomic absorption spectrometer (Lumex RA915M) coupled with a pyrolysis attachment (PYRO-915+). This setup allows for a continuous monitoring of Hg released during the sample heating. Calculations of risk associated to Hg volatilisation, leaching, and ingestion were performed using the relative amount of non-cinnabar (non-α-HgS) compounds determined through TD, considered as potentially mobile. Results were then compared with those obtained through the application of a SSE method commonly used for the assessment of Hg speciation in the investigated area. Almost all samples analysed through TD showed the occurrence of non-mobile red cinnabar (α-HgS), confirming the remarkable legacy of the mining source. Generally, although a slightly higher abundance of potentially mobile Hg forms was obtained through TD than SSE, the calculated risk resulted “acceptable” (hazard index < 1) using data from both techniques. Besides, it must be stressed that calculation performed through TD data are based on a larger number of samples, thus providing a greater representativeness of the mobility of the Hg species and associated risk in the investigated area. Considering also the good reproducibility of data obtained through TD and its celerity and accuracy in Hg species discrimination, the proposed approach could be considered as a valid and relatively low expensive tool for risk assessment at Hg contaminated sites. This is especially true for sites such as former Hg mining areas characterised by the occurrence of α-HgS, easily discriminable through TD.

How to cite: Floreani, F., Pavoni, E., Petranich, E., Antonini, P., Mauri, M., and Covelli, S.: Mercury speciation in soils through thermo-desorption technique as a rapid screening tool for risk assessment procedure at mercury-contaminated sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10434, https://doi.org/10.5194/egusphere-egu24-10434, 2024.

The occurrence of gaseous mercury pollution has to be identified and monitored through innovative methods and techniques, which would serve as a step toward strengthening the knowledge of the mechanisms of mercury dispersion in the atmosphere, in accordance with the provisions of the Minamata Convention on Mercury. Consequently, the aim of this work is to present the very first data obtained by directly and continuously measuring GEM (Mercury Elemental Gas) in the lower atmosphere through an original assembly of a UAV (Unmanned Aerial Vehicle, a heavy-lift octocopter) and a Lumex^® RA-915M (a portable spectrometer for gaseous mercury). A few sites pertaining to both the mining facilities of the former Hg-mining area of Abbadia San Salvatore (Mt. Amiata, Italy) and the surrounding urban zones were selected to test the performance and effectiveness of the UAV-Lumex^® combination at different heights. The octocopter agility and directional versatility, able to stop at selected altitudes, and the Lumex^® great sensitivity made it possible to shed light on the variability of GEM concentrations and to represent its distribution via dot-map graphical visualization, providing a tridimensional picture of GEM profiling during the flights. This approach allows checking in near real-time whether the guideline concentrations are eventually exceeded. More specifically, the acquisition system was optimized through: i) the use of a stand-alone GPS as a synchronization tool for Lumex^® and UAV GPS data; ii) the connection of a vertical sampling tube to the Lumex^® inlet to overcome the strong airflows of the UAV rotors; iii) the use of batteries for power supply to avoid the release of exhaust gases. Moreover, all flights were standardized based on previously acquired data thanks to the method accuracy and the UAV pilot experience, allowing reprogramming and repeating the routes in different times. The results showed significant concentration variations between the urban and the most contaminated mining area, and highlighted the differences when the flight was repeated at a later date.

How to cite: Cabassi, J., Lazzaroni, M., Giannini, L., Mariottini, D., Nisi, B., Meloni, F., Rappuoli, D., and Vaselli, O.: Investigating the 3D distribution of GEM (Gaseous Elemental Mercury) in the lower atmosphere via a UAV (Unmanned Aerial Vehicle) - Lumex® assemblage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10879, https://doi.org/10.5194/egusphere-egu24-10879, 2024.

The concept of Terroir, developed with respect to grape and wine, can be generalized to define the inseparable link between an agri-food product and its territory of origin as a determining element for its economic valorisation. While the terroir certainly impacts on physiological and compositional aspects of a crop, an important influence is due to the species diversification in cultivars. Therefore, both environment/soil and cultivar participate in defining the geographical authenticity of crops.

Geochemical-isotopic techniques are a powerful tool to authenticate a crop with respect to its geographical origin. The integration of multi-elemental analyses with the determination of isotopes such as carbon (δ¹³C) and nitrogen (δ¹⁵N) can allow a detailed mapping of the geographical origin of agricultural products. The stable isotopes of light elements present in crops offer a unique form of ‘isotopic signature’ that reflects the geochemical conditions of the soil together with the metabolic specificity of the plants (photosynthesis, N assimilation). This is crucial not only to authenticate the plant provenance, but also to support protected designations of origin (PDOs) and geographical indications (PGIs), strengthening the consumer’s confidence in the authenticity and quality of products.

In this first report, we have combined geochemical-isotopic and chlorophyll fluorimetric analyses of two red chicory (“radicchio rosso”, cv. Chioggia and cv. Treviso) cultivars typical of the Emilian coastal environment, but not yet recognized as PGI, different from analogous crops in Veneto Region. An effort in this respect is motivated by the special geochemistry of sandy coastal soils, which tend to be dry and exposed to salinisation phenomena.

Soil was thoroughly characterized based on its chemical-physical properties, including XRF analysis of major elements. A detailed analysis of elements in soil and plants was performed by ICP-MS-QQQ down to ultra-trace elements, and EA-IRMS analysis was done for the evaluation of C and N isotopic ratios. Plant phenotyping, based on chlorophyl fluorescence indexes, was performed to highlight the physiological specificities of the two cultivars, to put in relation with the stable isotope profile of light atoms.

The comparative results of the geochemical composition of the plant organs evidenced a cultivar-specific fractionation of some elements: cv. Chioggia had higher element absorption capacity than cv. Treviso, and both cultivars share an attitude to concentrate P, Cu and Mo. Upon translocation of elements from roots to leaves, especially the rare earth elements showed the specificity of the two cultivars, which can be differentiated based on the concentration of lanthanides as compared to the soil. A better use of mineral nutrients could be supported by higher photosynthetic performance in cv. Treviso than cv. Chioggia.

This research, to be further implemented, can constitute a useful database for the reconstruction of the geochemical-isotope profile for the geographical traceability of “radicchio rosso” and the possible further promotion of this crop in Ferrara province.

This research was allowed by phD fellowship granted by EUROPEAN SOCIAL FUND P L U S - The ESF+ 2021-2027 Programme of the Regione Emilia Romagna

How to cite: Martina, A., Aquilano, A., Ferroni, L., and Marrocchino, E.: Geochemical-isotopic and fluorimetric analyses for the characterization of two red chicory varieties in sandy coastal soil of the Ferrara province (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10952, https://doi.org/10.5194/egusphere-egu24-10952, 2024.

Volcanic eruptions are unpredictable and present a significant challenge for volcanic crisis management, primarily due to the variety of eruptive styles, ranging from effusive to explosive. By elucidating the dynamics of magma ascent, with a focus on degassing, we can better understand of the interconnections between petrological characteristics, geochemical and geophysical signals, volcanic hazards, and volcano monitoring. To this aim, lithium (Li), which has a high mobility in both silicate melts and crystals, has been used as a geospeedometer to monitor short-time processes, such as syn-eruptive magma ascent and degassing and post-eruptive processes (cooling). Yet, to appropriately interpret Li data in crystals from volcanic deposits, a clear understanding of the Li behavior and partitioning between the crystal-melt-fluid phases during an eruption is essential. Most of the Li partitioning data rely on glass inclusions and their host minerals, which do not always guarantee equilibrium conditions. Experimental data are largely missing, especially in the case of silica-rich hydrated magmas. Therefore, we provide Li contents and partitioning via phase-equilibrium experiments for analyzable-sized plagioclases crystallized from Li-bearing H2O-saturated rhyolitic melts at pressures from 50 to 150 MPa and temperatures of 800 and 875 °C. In addition to its applications in volcanology, this research could yield valuable information for assessing the economic viability of lithium in felsic deposits, specifically those with rhyolitic/granitic compositions (as highlighted by Benson et al., 2017), and in magmatic fluids. Moreover, it holds futuristic potential for extracting lithium directly from these fluids.

How to cite: Dupont de Dinechin, M., Martel, C., Balcone-Boissard, H., Rusiecka, M., Champallier, R., and Deloule, E.: Experimental Investigation of Lithium Partitioning among Plagioclase, Rhyolitic Melt, and H2O Vapor, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14481, https://doi.org/10.5194/egusphere-egu24-14481, 2024.

This research work focuses on reconstructing the anthropogenic fingerprint of the past 150 years through the high-resolution analysis of trace organic compounds preserved in Antarctic ice.

Over the decades, numerous persistent and semi-volatile organic pollutants were largely used in several industrial activities. Some of them proved to be highly toxic, posing a serious threat to human health and natural ecosystems. Consequently, international bans and agreements were established to reduce their industrial production. As a result, restrictions on one compound have led to increased emissions of other chemical substitutes. A rise-and-fall trend in the concentrations between well-established and emerging pollutants is expected in response to international legislative measures. High resistance to biodegradation and semi-volatility promote the long-range atmospheric transport of these molecules, which reach remote areas such as polar regions, where they accumulate as a result of cold condensation processes.

The extraction site GV7 (70°41' S, 158°51' E, 1950 m a.s.l.) is highly significant since it presents a high snow accumulation rate (241 ± 13 mm we yr-1). This feature, rare in recent archives, enables the analysis of trace organic compounds that would otherwise require considerably high amounts of matrix. The ice core (length: 50 m; diameter: 100 mm) is an ideal archive to investigate the “Great Acceleration” since it spans the last 150 years.

The novel analytical method specific for snow and ice applied in this work allows to recognize the evolution of a single compound over time in response to international bans and social changes. The multi-proxy approach adopted allows to identify trends in well-established and new generation organic pollutants as well as personal care products. More specifically, fragrances are compounds of increasing interest since they provide information on use and consumption related to changes in household and social habits.

Solid-phase extraction (SPE) combined with gas chromatography coupled with triple quadrupole mass spectrometry (GC-MS/MS) enable to significantly increase the analytical signal. In addition, samples were entirely processed in a stainless-steel clean room to reduce contamination, achieve low detection limits, and obtain high-resolution data.

Results show a change in the concentration of each compound on a time frame of 150 years. Since this is a pilot study, the processes involved in the transport and deposition of the analytes in deep ice are not yet fully understood and need further investigation. It is necessary to take into consideration possible changes in the use and consumption of organic molecules and potential variations in atmospheric transport.

Previous studies provide data on personal care products on surface snow, which are essential for a broader interpretation of the processes involved.

How to cite: Genuzio, G., Vecchiato, M., Argiriadis, E., Spolaor, A., Frezzotti, M., Barbante, C., and Capodaglio, G.: Trace organic compounds in an Antarctic ice core: a high-resolution analysis to reconstruct the anthropogenic fingerprint, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15658, https://doi.org/10.5194/egusphere-egu24-15658, 2024.

Mine dumps are man-made geological formations characterized by unique chemical, particle-size, bacterial, and physical and mechanical features, representing deposits or cumuli of crushed, grounded and roasted material. Processing plants of metallic poli-sulfide ore deposits have contributed to pollute soils and surface and ground waters in many areas worldwide. The southern sector of the Apuan Alps (northern Tuscany, Italy) hosts a number of small pyrite ± barite ± iron-oxide orebodies that have been exploited since at least the Middle Age, whose activity ceased at the end of the 20^th century. The most important mining areas were those distributed along a 10 km-long NE-SW strip in high Hg contents the southern portion of the Apuan Alps. In this framework, the Rezzaio treatment plant (Valdicastello Carducci, Pietrasanta), dismissed since 1991, was the site where ore bodies hosted within the metamorphic rocks of the Apuane Unit, mainly from Monte Arsiccio, Pollone and Buca della Vena mines were treated. The materials extracted from these mines were barite and iron oxides (both hematite and magnetite) used as weighting agents as drilling mud during petroleum drilling wells. Abandoned mining tunnels and dumps and plants for mineral treatment are still present in the area, posing a series of environmental threats. Our study focused on assessing the impact due to mercury contamination released by the treatment plant of Rezzaio by the past-mining activity. The aims of this study were to (1) determine the concentration of Gaseous Elemental Mercury (GEM or Hg0) in air and interstitial soil inside and outside the plant, including the working areas and the edifices where the workers were operating (e.g., offices, laboratory, rock storage); (2) assess the total amount of Hg in the top- and sub-soils, mostly developed on a small mining dump and (3) quantify the release of Hg by soil leaching tests by Milli-Q water. According to WHO and the Italian Legislative Decrees, the GEM values in air and outside the plant and in the plant edifices and mining structure are below the Recommended Exposure Limit. The spatial distribution of Hg indicates that up to 88 mg/kg were recorded in the top- and sub-soils, the highest contents being found on the small mining dump that is partly the bank of a creek. However, in most cases the concentration of Hg leachate were < 1µg/L, suggesting that mercury is likely trapped within crystalline silicate structures recalcitrant to chemical weathering. These results suggest that despite the high contents, mercury is not apparently playing a critical role as a contaminant in the Rezzaio area, being hosted in relatively insoluble minerals.

How to cite: Barbara, N., Meloni, F., Cabassi, J., and Vaselli, O.: Mercury contamination in a former mining plant of NW Tuscany (central Italy)  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15864, https://doi.org/10.5194/egusphere-egu24-15864, 2024.

Mining activities have a severe impact on fluvial systems. The dispersion of huge amounts of heavily polluted wastes contribute to mining-related river pollution due to runoff. Pollutants distribution in fluvial systems is controlled by the interplay between weather conditions (e.g., flooding events), geomorphic processes, and anthropic activities affecting sediments supply, erosion, transport, and (re-) deposition. Mercury (Hg) is listed as a critical contaminant due to its high toxicity, mobility, and persistence in the environment. Its use is progressively banned. As a result, Hg mining is now limited to a few countries. However, legacy mine wastes are still releasing Hg into the environment, particularly to fluvial systems. The Monte Amiata Mining District (MAMD, Southern Tuscany) was the 3rd largest Hg producer worldwide. Four river basins drain the MAMD. Among them, the Paglia River (PR) basin drains the SE sector of the MAMD, covering an area of 1320 km². The widespread Hg pollution and the low resilience to contamination of this river basin was demonstrated in previous studies. Extreme flooding events redistributed huge amounts of polluted sediments across the catchment. The Hg flux discharged by PR to the Tiber River, and ultimately to the Mediterranean Sea, was estimated around 11kg/y. However, this estimate is based on spot samplings. In this study, the relationship between Hg transported by particulate (Hg_p), total suspended solids (TSS) and water turbidity (Tb_w) for PR was investigated to set up a method for the calculation of Hg fluxes from TSS and Tb_w monitoring. Water samples were collected in different hydrological conditions between 2022 and 2023. Samples were taken along the PR, upstream and downstream of the Elvella creek confluence (ECC), a tributary that is not polluted by Hg, to evaluate its effects on the Hg budget. The samples were filtered and the TSS collected on the filters were analyzed for Hg. Part of the samples were analyzed also for Tb_w to investigate the relationship between TSS and Tb_w. TSS ranged between 1.3 and 621.4 mg/L, whereas Hg varied between 0.8 and 321.8 ng/L. Tb_w varied between 12.2 and 358 NTU and a linear relationship was found between TSS and Tb_w. The highest Hg and TSS values were measured during the recession phase of flooding events, whereas the lowest ones were found during low flow conditions. A linear relationship was also found between Hg and TSS. Hg was higher in the upstream samples than in those collected downstream the ECC, confirming that Hg source is the heavily polluted PR basin. The relationship between the two parameters could be applied to the indirect, continuous measurement of Hg fluxes discharged by PR with an automated TSS/Tb_w sensor. Such monitoring would allow assessing the variability of Hg pollution and transport across the PR basin in real time especially in case of flooding, that are expected to become more frequent due to climate change, leading to an increase of Hg delivery to the Mediterranean Sea.

How to cite: Nannoni, A., Annese, V., Fornasaro, S., Morelli, G., Ciani, F., Monnanni, A., Lattanzi, P., Rimondi, V., Costagliola, P., and Fagotti, C.: Particle-bound mercury transport across a mine-polluted fluvial system: towards a simple method to measure Hg flux from the Monte Amiata Mining District (Southern Tuscany, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16063, https://doi.org/10.5194/egusphere-egu24-16063, 2024.

Geochemical prospecting is a valuable tool for investigating the influence of the geological context on the composition of stream sediment and determining the existence of any natural or anthropogenic geochemical anomaly within a river catchment basin. Several indices have been proposed in scientific literature to assess sediment's environmental quality and the ecological condition of catchment basins. In environmental studies, these indices are usually based on applying ratios among the raw geochemical composition of the sediment at the sampling location and a value assumed as a reference for the undisturbed conditions (Background/baseline). However, the reference values are often determined while overlooking the potential influence of river dynamics on the variability of sediment composition, and this can compromise the robustness of the contamination assessment.

As a matter of fact, the chemical composition of a stream sediment sample is representative of the relative upstream catchment basin. The Sample Catchment Basin (SCB) method, which accounts for the dynamic nature of rivers, has been largely used in literature to correct the dilution effect impacting the composition of stream sediment, aiming at determining reliable geochemical background values to be used for mineral prospecting.

The main purpose of the study was to check if the use of the correction of the dilution effect to determine background values could also improve the performance of some contamination indices, favouring a more effective and accurate assessment of the environmental degradation affecting a river basin.

The Sarno River, known for its susceptibility to contamination from urban and industrial sources, served as a pertinent case study. A total of 96 samples were used to define the zone of influence of each sample through the elaboration of geomorphological and hydrological features; then, the background concentrations of each element were estimated by calculating the weighted average element content based on the areal proportions of lithologic units in each sample catchment basin. The values deriving from this step were then used as a reference to calculate the degree of contamination for each SCB.

The contamination indices were calculated and mapped by using both non-diluted and dilution-corrected background data.

A comparative analysis was performed among the results obtained to assess if sensitive changes occurred to the spatial and statistical distribution of used indices and to determine if an improvement in performance could be obtained.

 This study represents a methodological benchmark for future research focusing on environmental risk assessment of stream sediment.

How to cite: Iannone, A., Guarino, A., Pacifico, L. R., and Albanese, S.: Can contamination indices performance be improved by accounting for the dilution effect when dealing with stream sediments? A case study from southern Italy., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16836, https://doi.org/10.5194/egusphere-egu24-16836, 2024.

Understanding the transfer of contaminants from soil to plants, especially agricultural products, is essential in environmental science, particularly in the context of risk assessment and the development of sustainable agricultural practices. The estimation of transfer factors (TFs) (Singh et al., 2011), which quantify the uptake of elements or pollutants by plants from the surrounding soil, serves as a crucial parameter in evaluating potential ecological and human health risks, as these elements could enter the food chain (Ozhovan and Kremenetskiy, 2018).

For this study, the Transfer Factors soil-to-plant were estimated using the bioavailable concentrations (Guarino et al., 2022) of Potentially Toxic Elements (PTEs) identified by Italian law (D.lgs. 152/2006) in the agricultural soils and the elemental concentration in the primary agricultural products (PAP). These latter are freshly harvested fruits and vegetables, which retain their integrity and freshness as they have not undergone significant processing, collected across the entire region through the Campania Trasparente project (www.campaniatrasparente.it).

The aim of this study was to compare various Transfer Factors (TFs) among the most numerous vegetal species and potentially highlight different behaviours. A robust multivariate statistical approach, such as Robust Principal Component Analysis (RPCA) was applied to the TFs, and a multiple regression, using the stepwise method, was performed, with Principal Components as dependent variables and soil physical parameters (grain size, organic matter, pH, cation exchange capacity, salinity, electrical conductivity) as independent variables.

Our findings reveal distinct patterns in the soil-to-plant transfer factors for various elements, emphasizing the role of soil properties, plant species, and environmental conditions. Results reveal that, within the Campania region, the highest TFs for the most vegetal species are associated with Zn and Cu. Specifically, RPCA indicates a positive correlation between Zn and Co TFs. In the end, the multiple regression analysis highlights that clay presence and cation exchange capacity are the primary soil physical factors influencing TFs across different plant species.

This integrated approach could provide a comprehensive understanding of soil-plant transfer processes and the impact of soil physical parameters on TFs in regional cultivations. The study helps better understand the impact of soil physical parameters, such as cation exchange capacity (CEC), grain size, organic matter, etc., on vegetal species growth. It can lead to well-informed decisions regarding crop selection, fertilizer application, irrigation, and other factors.

References:

Guarino, A., Albanese, S., Cicchella, D., Ebrahimi, P., Dominech, S., Pacifico, L.R., Rofrano, G., Nicodemo, F., Pizzolante, A., Allocca, C., Romano, N., De Vivo, B., Lima, A., (2022). Factors influencing the bioavailability of some selected elements in the agricultural soil of a geologically varied territory: the Campania region (Italy) case study. Geoderma 428, 116207.

Jaswant Singh, Suraj K. Upadhyay, Rajaneesh K. Pathak & Vidhu Gupta (2011). Accumulation of heavy metals in soil and paddy crop (Oryza sativa), irrigated with water of Ramgarh Lake, Gorakhpur, UP, India, Toxicological & Environmental Chemistry, 93:3, 462-473.

Ozhovan M, Kremenetskiy A. (2018). Transfer Factors: Concepts and Applications in Soil-Plant Systems. Boca Raton, FL: CRC Press.

How to cite: Pacifico, L. R., Guarino, A., Iannone, A., Pizzolante, A., Esposito, M., Brambilla, G., and Albanese, S.: Comprehensive analysis and multivariate statistical approach of Transfer Factors soil-to-plant estimated from bioavailable concentrations in agricultural products: the case study of the Campania region (Southern Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17147, https://doi.org/10.5194/egusphere-egu24-17147, 2024.

In the past 20 years, the occurrence of tungsten-related health and safety incidents has drawn the close attention of scholars to the toxicity of tungsten and its health and environmental effects. The upper limit of tungsten concentration in water, its mobility and toxicity are all closely related to its speciation. Although polytungstates have been proven to be more toxic and migratory than monomeric tungstates, there is limited information about their abundance in natural environments due to the lack of a reliable analytical approach for determination. In this study, we conducted a simultaneous analysis of monomeric and polymeric tungsten species in natural water using reverse-phase ion pair chromatography coupled with inductively coupled plasma mass spectrometry. Polytungstates and five monotungstates, including tungstate as well as mono, di, tri, and tetrathiotungstate, were chromatographically separated within 35 min of using ethanol (12 - 48% gradient) as the mobile phase. The detection limit of polytungstates was 1.50 µg/L. Although common for the analysis of metals, experimental studies based on electrospray ionization - high resolution mass spectrometry (ESI-HRMS) have indicated that samples containing polytungstates should not be acidified, as it could result in the transformation of monotungstates to artifact polytungstates. Overall, our study offers an effective method for the analysis of various tungsten species, especially polytungstates, at environmentally relevant concentrations.

How to cite: Zhao, Q. and Hu, S.: Reverse phase ion pair chromatography coupled with inductively coupled plasma mass spectrometry as a method for tungsten speciation in natural waters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17460, https://doi.org/10.5194/egusphere-egu24-17460, 2024.

Mercury (Hg) represents one of the top ten chemical elements of significant public concern according to the World Health Organization. In 2013, the Minamata Convention was established aiming to reduce, control and possibly eliminate the use and release of mercury in the environment. The Global Mercury Assessment 2018 estimated annual global mercury anthropogenic emissions at around 2200 tons, while the contributions of primary natural sources (e.g., volcanic activity) appear significantly uncertain.

The aim of this study is to better constrain the origin and quantity of mantle-derived Hg by integrating the current available data from experimental petrology, geochemical analyses of sedimentary rocks the Hg anomaly of which is linked to large-scale magmatic events, chemical data of igneous rocks and Hg measurements from volcanoes and minerals by in situ and in satellite remote sensing.

The volcanic Hg is known to be characterized by an atmospheric residence period of 0.5-2 years (Bagnato et al., 2007) that allows it to distribute over the globe in the form of Hg⁰ and Hg²⁺.Inizio modulo The oxidation of Hg⁰ to Hg²⁺ causes mercury to dissolve into aqueous fluids. Part of Hg directly migrates to the atmosphere, precipitate into sedimentary basins and eventually long-term sequestrate in marine sediments (Grasby et al., 2019).

Sharp Hg anomalies have been detected in several stratigraphic layers with concentrations varying from 20 ppb (La Bédoule, France) to 90 ppm (Grane field, southern Viking Graben, Norwegian North Sea) to be representative of mass extinction anoxic and Large Igneous Province events (i.e. Greater Ontong Java and North Atlantic Igneous Province) such as Selli oceanic anoxic event and Palaeocene-Eocene Thermal Maximum, respectively (Grasby et al., 2019 and reference therein). The analyses of current Hg volcanic emissions along with stratigraphic geochemical anomalies highlight transport processes of deeply seated Hg of mantle origin (Shen et al., 2023). The interior of Earth is proposed to store about 10 ppb of Hg (BSE model, McDonough and Sun 1995) within a variety of igneous rocks both intrusive (peridotites, pyroxenites and gabbros) and effusive (basalts), the majority of which (about 5 ppb) is hosted by ophiolites (Canil et al., 2015).

Further, the current global volcanic Hg flux ranges from 0.6 ton·yr^-1 to over 1000 ton·yr^-1 (Edwards et al., 2021) pointing out the high volatility of mantle-derived Hg that is confirmed by the established link between volatile-driven LIP events and Hg anomalies distributed worldwide. Additional sources of natural Hg emissions are represented by hydrothermal mineralization (e.g. cinnabar) that testify the dominant role of SO₂ and H₂S emissions in volcanic and hydrothermal systems, respectively.

We will present a preliminary database of global Hg concentration that allows to model the deep Hg cycle based on the effect of magma-mineral element distribution and the role of pressure-temperature-mantle redox state through space and time.

How to cite: Benedetti, F., Marras, G., Brandano, M., Calabrese, S., Bosi, V., Ricciardi, A., and Stagno, V.: An updated database of mercury emissions based on remote sensing, geochemical surveys and laboratory experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18436, https://doi.org/10.5194/egusphere-egu24-18436, 2024.

Stalagmites in karstic caves may serve as paleoclimate proxies, especially in regions missing glacial ice cores or other continental proxies. Specifically, the laminae revealed in a stalagmite cross-sectional cut can be related to the past upstream flows and soil coverage above the cave. The shape of these laminae, and therefore of the stalagmite top surface, thus change over time in response to variable environmental conditions. However, the effect of the past flows on such shape variability remains poorly understood. Previous models describing stalagmite growth thus involved strong simplifying assumptions regarding the aerodynamics and hydrodynamics of drops impacting stalagmites in caves. For instance, drops were assumed to always land at the apex of the stalagmite, thereby feeding the thin residual film covering it in one central point, while it was recently shown that the drop impacting position is sometimes scattered over several centimeters, which may have a non-negligible effect on stalagmite width [1]. The concave shape exhibited by some stalagmites was also associated with drops splashing at impact, while most drop impacts in caves lead to splashing and cannot, therefore, be related to a particular stalagmite shape [2]. Another assumption of previous stalagmite growth models is that the thin residual film lying on top of the stalagmite remains uniform in time and space, which may not always be accurate.

We thus propose to study the evolution of this residual film in time and space. Starting from an initially dry stalagmite, the film thickens because of the liquid brought by the successive drops, until it reaches a steady state. The thickness of the film at steady-state results from the balance between the incoming flow of drops falling on the stalagmite, and the film depletion through gravity-driven drainage. If this drop inflow is interrupted, only the drainage remains. We are interested in assessing the effect of the main factors influencing the film thickness evolution during these three phases, namely: (i) the underneath stalagmite shape, and (ii) the drop dripping frequency, i.e., the amount of liquid brought over a certain time. To achieve this, we record film thickness measurements during the filling, stationary and sole drainage phases on actual stalagmites, both in caves and in a lab setting. The caves provide a great diversity of shapes while the lab measurements allow to systematically vary the drop dripping frequency. We complete these measurements by a reduced-order modeling of the film thickness in time and space, using Reynolds lubrication equation expressed in curvilinear coordinates to account for the various existing stalagmite profiles. We obtain a good agreement between the experimental measurements and the results provided by the model with a set of parameters representing adequately the stalagmites of our dataset. We finally show that, depending on the stalagmite shape, considering the film as uniform in time and space may remain a valid assumption, but this is not always the case.

[1] Parmentier J. et al, P. R. Soc. A. (2019), https://doi.org/10.1098/rspa.2019.0556
[2] Parmentier J., Terrapon V. and Gilet T., Phys. Rev. Fluids (2023), https://doi.org/10.1103/PhysRevFluids.8.053603

How to cite: Parmentier, J., Terrapon, V., and Gilet, T.: Gravity-driven drainage of a thin film on a stalagmite , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18537, https://doi.org/10.5194/egusphere-egu24-18537, 2024.

The present work is based on a full-scale project for the treatment of port sediments with high Hg concentrations. The port area of this work is located in the Principality of Asturias (northern Spain). Preliminary studies for the implementation of a dredging activity on the sediments of the Llanes port showed Hg concentrations in the sediments ranging from 0.19 to 1.13 µg g^-1, with an average of 0.81 µg g^-1. This Hg average concentrations exceeds the legal threshold in Spanish territory for returning dredged sediment to the sea, so that according to current legislation it must be extracted from the coastal system and managed on land, generating a substantial loss of a significant volume of sediment in the system. In order to improve a circular economy and to be able to manage these Hg-contaminated materials to be dredged more efficiently, laboratory-scale tests verified that the Hg contamination was mostly found in the finets fraction <63µm. With these previous results and with regional governmental support, the company EXCADE S.L. in collaboration with the University of Oviedo designed and built a full-scale plant based on the treatment of contaminated sediments by cyclone for the efficient removal of the fine contaminated fraction.  Between June and August 2023, a total of 8,000 m³ of contaminated sediments from this port area were processed in a first phase through this treatment plant. The particle size and the Hg concentrations in the treated material were monitored every two working days, and after the treatment of all the material, four representative samples of the total volume treated were sent to an external laboratory to validate the results obtained during the procedure. The monitoring results showed that the treated material had fine material concentrations of less than 5%, and that the Hg concentration ranged from 0.05 to 0.13 µg g^-1, which resulted in a 7-fold reduction of the initial average Hg concentration in the sediments. The same occurred with the results from the external laboratory that showed that the treated material had fine material concentrations of less than 5%, and that the Hg concentration ranged from 0.13 to 0.17 µg g^-1. These Hg concentrations in the treated material were within the legal range in Spanish territory, which is why the treated material was authorized for deposit at sea. Throughout 2024, the same procedure will be carried out on 12,000 m³ of new contaminated by Hg material to be dredged to validate the results of this first real-scale experience for the treatment of sediments contaminated by high Hg concentrations.

How to cite: garcia-Ordiales, E., Barquero Peralbo, J., Navarro Murillo, E., Rico Fernandez, P., and Cienfuegos Suarez, P.: Experiences in a full-scale cyclone plant treatment of Hg-contaminated port sediments., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18550, https://doi.org/10.5194/egusphere-egu24-18550, 2024.

Materials research applied to archaeological ceramic artefacts has garnered widespread interest among scientists, architects, engineers, and archaeologists focused on safeguarding architectural heritage. These ancient structures within historic city centers encapsulate the distinctive history and visual essence of each city across different eras. Assessing both old and new materials following damage to these historical edifices becomes crucial for predicting their behaviour during restoration. This endeavour not only aims to analyze and preserve these artifacts but also aims to explore the knowledge and craftsmanship involved in their creation and use. Characterizing building materials primarily targets preservation and restoration goals, encompassing the origins of historical raw materials, understanding archaeological artifact changes, determining original firing methods, and reconstructing manufacturing technologies. Bricks and ceramics, resembling fired artificial rocks, retain geological imprints from their claystone origins, impacted by local geological settings influencing material availability and building techniques. Take, for instance, Ferrara, a Medieval city in Northeast Italy, strategically positioned between the Adriatic Sea and the Po alluvial plain. Its prosperity during the Renaissance under the Estense family was bolstered by extensive modifications to the city, predominantly utilizing locally abundant silico-clastic sediments for construction.

The focus of this research on historical bricks and terracotta decorations from prominent Medieval and Renaissance buildings in Ferrara is to understand the composition of these ancient materials to aid in planning effective restoration treatments, identifying causes of decay, selecting suitable replacement materials, and avoiding incorrect restoration choices. Analyzing the chemical and geological attributes of these materials provides valuable insights into their manufacturing techniques and origins. Moreover, by comparing obtained data with regional sediment records, it has been possible to ascertain the nature and sources of the original raw materials.

How to cite: Marrocchino, E. and Vaccaro, C.: Geochemical characterization of bricks and terracottas used in historical monuments in Ferrara (Italy): Reference to raw materials and production technique, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19518, https://doi.org/10.5194/egusphere-egu24-19518, 2024.

Riparian vegetation plays an important role in fluvial ecosystems. River drainage in abandoned mine sites is often source of heavy metals through transport of contaminated sediments. In those areas riparian vegetation may take up contaminants from riverbanks soil, acting as a temporary storage of metals. In this study, the potential mercury (Hg) in plants growing on soil anomalous in Hg was quantified to evaluate its storage effectiveness, and the potential as a secondary Hg source to the atmosphere in case of fire, or upon anthropic utilization as biomass.
Riparian trees along a section of the Paglia River (Tuscany, Italy), draining the abandoned Monte Amiata Hg mining district, the 3rd Hg producer worldwide in the past, were sampled from the riverbanks. The riparian vegetation is occasionally cut during bank maintenance, and the resulting wood may end up into wood chips for solid biofuel. Poplars (Populus spp.) are the most abundant species naturally widespread along the Paglia riverbanks, together with Robinia spp. and Quercus spp.. 
Cores of trunks (8/10 cm long, 0.5 cm diameter) from 50 trees were sampled from fives sites using a drill corer. At each site, a soil sample was collected. 
In soils, Hg ranged from 3.5 to 52.8 mg/kg, above the Italian limit for soil (1 mg/kg; D.Lgs.152/2006). Preliminary data in trees, show Hg ranges between 0.5 and 93 ug/kg. Anomalous Hg concentrations (195-353 ug/kg) in few samples are probably associated to soil particles trapped in the tree barks. Except for these values, Hg concentrations in trees are below the recommended Hg limit (100 ug/kg) for high quality solid biofuels (European EN ISO 17225, 2021), thus posing little to moderate impact on the value of the locally harvested wood chips and the potential health risk for Hg0 emissions. On the other hand, in case of wildfires, Hg stored in trees bole wood (about 0.6 kg estimated in the studied area) can be released from the burning trees and from the subjacent soil. Thus, vegetation represents a potential secondary source of Hg₀ to the atmosphere. Results highlight the importance in similar contaminated areas of metals fate investigation in soil and plants to assess the actual risks to the surrounding environment (biota, human health, and animals) posed by Hg emissions in case of fire, or for example by biomass used for energy production. Remediation strategies in these areas should include a wise management of riparian vegetation as a tool for mitigation of Hg release in the environment.

How to cite: Morelli, G., Ciani, F., Costagliola, P., Fagotti, C., Lattanzi, P., Monnanni, A., Nannoni, A., and Rimondi, V.: Quantification Of Mercury (Hg) In Riparian Trees Along The Paglia River, Monte Amiata Hg Mining District (Italy): Implications For A Sustainable Environmental Management And Risks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19595, https://doi.org/10.5194/egusphere-egu24-19595, 2024.

The EU-funded CRM-geothermal project aims to integrate the extraction of critical raw materials and geothermal heat from deep geothermal reservoirs. Within the project, extraction technologies and their economic and environmental feasibility are tested and evaluated across several geological regions in Europe and East Africa.

  The focus of this study is the North German Basin, a typical sedimentary basin that initiated rifting in the late Carboniferous period, accumulating various sediments to a thickness of up to 10–12 km. Located in central Europe it stretches over an area from Poland to the Netherlands, traversing across North Germany.

The succession is beginning with Permian volcanic rocks at the base, and overlain by alternating layers of mud-, silt- sandstones and evaporates; some of which have already been identified for geothermal energy extraction (e.g. Neustadt-Glewe, Schwerin, and Potsdam). Up to now, the extraction of lithium (Li) has not been explored, despite the existence of elevated Li concentrations occurring in formation fluids of the Rotliegend and Bunter sandstone.

In this study the potential content of selected critical and valuable elements (Li, Sr, Cu) and their availability in various formations of the North German Basin was assessed. For this purpose, cuttings from different formation rocks from one deep well (GrSk04/05; 4000 m depth) were first analyzed for bulk concentrations of these elements. Most promising samples (with Li up to 74 ppm, Cu up to 214 ppm, and Sr with up to 2334 ppm) were selected from Muschelkalk, Bunter sandstone (Dethfurt), Zechstein (Ohre), Permian Rotliegend sandstone (Hannover), and volcanic rocks)  for a sequential extraction. This method provides indication on the type of elemental bonding within minerals, allowing to estimate the availability and sustainability of the CRM in the respective formation fluids.

How to cite: Regenspurg, S., Thomas, A., Stammeier, J. A., Schiepersky, F., Scheck-Wenderoth, M., and Kieling, K.: Critical raw materials from geothermal fluids: Potential in the North German Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19791, https://doi.org/10.5194/egusphere-egu24-19791, 2024.

Mercury is a worldwide contaminant, with a usual concentration range of 10 to 100 μg kg^-1 in the marine/oceanic sediments. The Bohai Sea, the largest gulf in China, is nearly enclosed by densely populated and industrialized land and connects to the northwestern Pacific Ocean via the Bohai Strait. The sediment core (profile) may record anthropogenic mercury history. A 476-cm sediment core was collected and sectioned into 1-cm slices, which were analyzed for mercury and conservative tracer scandium. Mercury content ranged from 14.4 to 35.5 μg kg^-1 while scandium content ranged from 9.57 to 13.1 μg kg^-1. Overall, mercury content increased from the sediment profile base up to top while scandium content decreased, showing that anthropogenic activities around the bay led to mercury enrichment and accumulation in the sediment. In details, mercury content in the sediment ranged from 14.4 to 17.4 μg kg^-1 and averaged 16.3 μg kg^-1 from 476-cm depth up to 351-cm depth. This average mercury content is considered as its geochemical base level in the bay. From 351-cm depth up to 181-cm depth, mercury content in the sediment ranged from 16.6 to 20.1 μg kg^-1 and averaged 18.4 μg kg^-1. The fluctuations in mercury content in this period might be related to climate change. Mercury content in the sediment slowly increased from 16.9 μg kg^-1 at 181-cm depth to 22.8 μg kg^-1 at 38-cm depth, which is supposed to be related to anthropogenic activities. Afterwards, mercury content in the sediment rapidly increased from 22.8 μg kg^-1 at 38-cm depth to 35.1 μg kg^-1 at 21-cm depth and fluctuated between 33.4 and 35.5 μg kg^-1 from 21-cm depth up to 9-cm depth. This rapid and high mercury enrichment and accumulation in the sediment is connected to the intensive anthropogenic activities around the bay. Subsequently, mercury content in the sediment decreased to 26.3 μg kg^-1 at 5-cm depth and then increased to 29.0 μg kg^-1 at the depth of 0-1 cm. Therefore, the mercury concentration profile in the 476-cm sediment core records the anthropogenic mercury pollution history in the Bohai Sea and can be used to estimate anthropogenic mercury mass and accumulation flux in the sediment.

This study was funded by the National Natural Science Foundation of China (42277366).  

How to cite: Lin, C., Ouyang, W., He, M., Liu, X., and Wang, J.: Vertical concentration profile of mercury in a 476-cm sediment core from the Bohai Sea: Inferring anthropogenic influence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20063, https://doi.org/10.5194/egusphere-egu24-20063, 2024.

The abandonment of industrial waste frequently leads to acid drainage affecting groundwater and severely impacting the environment or urban infrastructure. The severe impacts of the acid drainage are related, besides the extremely low pH reached in the affected waters, to the subsequent mobilization and spread of toxic heavy metals such as As, Fe, Cu, Cd, Ni, Pb, and Zn in highly oxidizing environments. The hydrogeology and hydrochemistry of an urban area in Al-Mozara (Zaragoza, Spain), built over an old industrial zone with pyrite roasting waste deposits that experienced acid drainage problems, has been investigated and modelled. Drilling and piezometer construction, and groundwater samples taken during the activities of the SAGE4CAN project, revealed the existence of a perched aquifer within old sulfide mill tailings, where the building basements interrupted the groundwater flow leading to a water stagnation zone that reached extreme acidity values (pH < 2), by drastically increasing the reaction times. A groundwater flow reactive transport model was developed with the software PHAST to reproduce flow and groundwater chemistry, to be used as a predictive tool for guiding and selecting the optimal remediation actions. The model reproduced the measured groundwater chemistry by simulating the kinetically controlled pyrite and portlandite dissolution. Further, the model predicts that an extreme acidity front (pH < 2), coincident with the Fe (III) pyrite oxidation mechanism taking dominance, is propagating by 30 m/year. The incomplete dissolution of residual pyrite (up to 18 % dissolved by the end of the simulations) predicted by the model indicates that the acid drainage in this aquifer is limited by the flow regime rather than by sulfide availability. The construction of additional water collectors between the recharge source and the stagnation zone has been proposed, together with periodical pumping out of acid water from the stagnation zone. The study findings are expected to serve as a useful background for the assessment of acid drainage and remediation techniques in urban areas by numerical modelling, since urbanization of old industrial land is rapidly increasing worldwide. 

How to cite: Jiménez, J., Marazuela, M. Á., Baquedano, C., Martínez-León, J., Sanchez Navarro, J. Á., Cruz-Pérez, N., Santamarta, J. C., and García-Gil, A.: Reactive transport model of an extreme acidic perched aquifer within roasted pyrite waste in a fully urbanized area (Zaragoza, Spain) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20228, https://doi.org/10.5194/egusphere-egu24-20228, 2024.

Quercus ilex is a vascular plant, a tree of large size, which is one of the most common species present in central Spain. Almadén (Ciudad Real province, South-central Spain) is the centre of a mining area active since prehistoric times, particularly for mercury, but also for others potentially toxic elements (PTEs: Pb, Zn, Ag, Cu), and in this area the Q. ilex constitutes woods, as well as the so called ‘dehesas’, a characteristic landscape with these trees scattered with variable density in pasture areas.

In this work we have sampled and analysed Hg and other PTEs (data not shown here) in the leaves from a wide area, of some 2,300 Km², located around the Almadén mine and site. A total of 88 samples were taken, prepared, and analysed, using the Atomic Absorption Spectrometry with Zeeman effect combined with a process pyrolisation, with a LUMEX RA-915 series equipment.

The area corresponds to the southernmost Central Iberian Zone of the Iberian Hesperian Massif, characterized by Palaeozoic and Pre-Palaeozoic substrates. In particular, the samples are distributed in three geological subdomains: the Almadén syncline in the north, the Alcudia anticline in the centre and the Guadalmez syncline in the south. Siliciclastic Paleozoic detrital rocks are in the majority in both synclines, while the pre-Paleozoic rocks of the Alcudia anticline are mainly dominated by schists and greywackes. 

Mercury uptake by plants occur through their leaves, and it accumulates in these, as proven empirically and experimentally. Besides, the presence of Hg in the atmosphere depends on the eventual presence of discrete sources, such as mines or dumps, or on the Hg emissions from contaminated soils.

Our results show that Hg concentrations in Q. ilex leaves are conditioned by the presence of discrete sources in the Almadén syncline (the Hg mines present in this region), with a mean value of 197 ng/g ± 169, reaching even 1,000 ng/g in areas close to the main sources of atmospheric Hg. On the other hand, in the Alcudia Valley (99 ng/g ± 170) and the Guadalmez syncline (64 ng/g ± 192) the concentrations are lower and show a certain variability that may be related to the possible presence of the element in the soil in the form of anthropogenic contamination, as this research team has demonstrated in recent scientific publications.

How to cite: Barquero Peralbo, J. I., Esbrí Víctor, J. M., Ntutumu, D. M., Minang, C. M., Lorenzo Álvarez, S., González Valoys, A. C., and Higueras, P.: Regional distribution of mercury in the leaves of Quercus ilex in the Almadén area (Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20759, https://doi.org/10.5194/egusphere-egu24-20759, 2024.

Four jellyfish species, ctenophoran Mnemiopsis leidyi and scyphozoan Cotylorhiza tuberculata, Chrysoara hysoscella and Rhizostoma pulmo were collected in summer of 2017 in the Gulf of Trieste (northern Adriatic Sea) and analysed for Hg and other metal(loid)s to assess their bioaccumulation and biomonitoring potential. No significant differences in Hg levels (0.06-0.22 µg/g dry mass) were observed between the studied species but all significantly concentrated Hg well above the dissolved Hg seawater levels (5 ng/L) of the gulf. The studied species have diverse diets consisting primarily of various plankton groups. C. hysoscella feeds mainly on mesozooplankton (>200 µm) R. pulmo and C. tuberculata mostly consume microzooplankton (50-200 µm) while M. leidyi preys on various organism (and particles) in the water column. In addition, C. tuberculata harbours autotrophic endosymbionts (microalgae). Considering their feeding behaviour, it appears that studied jellyfish species do not bioaccumulate Hg, nor other metal(loid)s, along the pelagic food web. Hence, the Hg levels in jellyfish are probably the consequence of the dissolved metal (passive and active) uptake. Moreover, the methodological approach analysing the jellyfish freeze-dried samples containing salt can distort the real picture and the Hg/C_org. ratio could better describe the metal level in the gelatinous organism. However, considering the high Hg bioconcentration factor (log BCF >5), jellyfish can be used aa a useful bioindicator for Hg, and other metal(loid)s, dissolved in seawater.     

Keywords: Jellyfish, coastal waters, mercury, bioconcentration, contamination, bioindicator

How to cite: Faganeli, J., Tjasa, K., Darja, M., Alenka, M., and Ingrid, F.: Mercury in the coastal pelagic food web: phytoplankton, zooplankton and jellyfish, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22463, https://doi.org/10.5194/egusphere-egu24-22463, 2024.

Identifying the impurities that promote the selection of specific twin laws of gypsum has relevant implications for the geological studies aimed at interpreting the gypsum depositional environments both in ancient and modern deposits, and overall, on Mars surface, where “swallowtail” gypsum twin habit has been recently observed. However, because of the limited knowledge of morphological, crystallographic, and optical characteristics of the five twin laws of gypsum, relatively little has been done to understand which impurities exert a critical role in the selection of different twin laws and how this may impact our awareness about their occurrence in nature. Typically, the 100-contact twin law has been the only twin law of gypsum known so far in nature. However, some sedimentological-stratigraphic studies suggested this might not be the only widespread one. In this work, we firstly provide a geometric-crystallographic background of the five twin laws of gypsum, allowing researchers to recognize the twin laws only by the measurement of i) their re-entrant angle value and ii) the extinction angle formed between the two individuals using crossed polarizers in optical microscopy. Moreover, we show specific crystal growth laboratory experiments designed to improve our understanding of different habits and twin laws of gypsum occurring with and without the addition of carbonate ions in solution. The main results suggest that the different orientation of primary fluid inclusions with respect to the twin plane, and the main elongation of the sub-crystals making the twin, are a useful tool to distinguish between 100 and -101 twin laws, whose geometry is otherwise very hard to distinguish, especially in rock samples. Moreover, gypsum twins obtained by crystal growth laboratory experiments are compared with those detected in natural environments and the occurrence of the -101 twin law is suggested occurring in evaporitic-sedimentary environments. These results provide new insights into the mineralogical implications of twinned gypsum crystals and their potential use as a tool for a deeper comprehension of the natural gypsum deposits.

How to cite: Cotellucci, A., Otálora, F., Canals, À., Criado-Reyes, J., Pellegrino, L., Bruno, M., Aquilano, D., Garcia-Ruiz, J. M., Dela Pierre, F., and Pastero, L.: New insights on gypsum twinned crystals: mineralogical implications for natural gypsum deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-176, https://doi.org/10.5194/egusphere-egu24-176, 2024.

When exposed to high-temperature conditions (~1670°C), zircon crystals (ZrSiO₄) decompose according to the reaction: ZrSiO₄→ZrO₂+SiO₂ [2,8]. Under optical and electron microscopes, decomposed zircons are easily identified by the presence of bright rims of baddeleyite (ZrO₂) surrounding the unaltered primary crystal core (ZrSiO₄). Due to the high temperatures needed for this reaction to occur (i.e., exceeding the highest temperatures normally reached by magmatic processes or wildfires on the Earth’s surface), finding decomposed zircons in natural glass has become a handy unequivocal way to relate natural glass to extreme processes like meteoritical impacts [1], airbursts [6], or lightning [3]. If recognizing fulgurites (i.e., products of lightning) is more easily done because of their morphology, the identification of impact glasses can be problematic, especially when they are not associated with a known impact crater. This work aims to demonstrate the reliability of zircon decomposition as a geothermometer, used to identify impact (or airbursts) glasses.

Through high-temperature experiments, we show that the decomposition of zircons can occur in natural systems at lower temperatures than the ones predicted by models. At T=900-1000°C (P=1 bar, exposed to air), in the presence of Ca-sulfates and NaCl-rich soil called ‘caliche’ (from the Atacama Desert, chosen for its relation with one of the most recent debated case, that of Pica glass – [4,5,6,7]), zircons decomposed forming the typical bright rims. Using FEG-SEM-EDS, Raman spectroscopy, and TEM (on thin foils prepared using FIB), however, we show that the Zr-rich rim mineralogy in our experiments differs from previous petrographic descriptions, with assemblages of baddeleyite, baddeleyite + Ca-Zr-oxide, or only Ca-Zr-oxide.

In conclusion, we demonstrate that decomposed zircons could also result from lower temperature processes than impacts or airbursts and should be used more carefully in assessing the origin of glasses. Also, we suggest that a more detailed mineralogical characterization of decomposed zircons (rarely done after their detection) is needed to correctly assess the formation conditions of samples containing such rims.  

References

[1] El Goresy A., 1965. Baddeleyite and its significance in impact glasses. Journal of Geophysical Research, 70:3453-3456.

[2] Kaiser A., et al., 2008. Thermal stability of zircon (ZrSiO4). Journal of the European Ceramic Society, 28:2199-2211.

[3] Kenny G.G. and Pasek M.A., 2021. The response of zircon to the extreme pressures and temperatures of a lightning strike. Scientific Reports, 11:1560.

[4] Roperch P., et al., 2017. Surface vitrification caused by natural fires in Late Pleistocene wetlands of the Atacama Desert. Earth and Planetary Science Letters, 469:15-26.

[5] Roperch P., et al., 2022. Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile: COMMENT. Geology, 50.5:e550.

[6] Schultz P.H., et al., 2022. Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile. Geology, 50.2:205-209.

[7] Schultz P.H., et al., 2022. Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile: REPLY. Geology, 50:e551.

[8] Timms N.E., et al., 2017. A pressure-temperature phase diagram for zircon at extreme conditions. Earth-Science Reviews, 165:185-202.

How to cite: Musolino, A., Devouard, B., Rochette, P., Roperch, P., Zanetta, P.-M., Seydoux-Guillaume, A.-M., Ferry, D., and Campos, A.: Decomposed zircons: A reliable geothermometer to identify impact and airburst glasses?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-565, https://doi.org/10.5194/egusphere-egu24-565, 2024.

The Karkonosze granite (~320–312 Ma) is interpreted as a syn-collisional to magmatic arc intrusion. It is known for distinct symptoms of post-magmatic activity, including formation of intragranitic pegmatites observed in Szklarska Poręba quarry with overprinted W–Sn–Mo–Bi hydrothermal mineralization (e.g., Kozłowski et al., 1978; Pieczka & Gołębiowska, 2012).

Tin mineralization in the granite quarry at Szklarska Poreba is represented by cassiterite (Karwowski et al., 1972), Sn-rich titanite, malayaite, stokesite, and rare tin sorosilicates – kristiansenite, kozłowskiite and silesiaite (Evans et al., 2008;  Pieczka et al., 2022, 2023) The presence of all the above-mentioned mineral phases was confirmed by chemical microanalysis using the electron probe microanalyzer JEOL SuperProbe JXA-8230 and structure refinement. Cassiterite was recognized in an association mainly with scheelite, molybdenite, wolframite, chalcopyrite, and pyrite. These minerals crystallized from high-temperature aqueous fluids, subsequently followed by sulphide-rich stage (Karwowski et al., 1973). Sn-rich titanite, forming an isomorphic series with malayaite, CaTi[SiO₄]O–CaSn[SiO₄]O, shows chemical heterogeneity, with a maximum SnO₂ content up to 15.88 wt% (32 mol% Sn end-member), and elevated Nb₂O₅ (up to 9.85 wt%), Ta₂O₅ (up to 7.88 wt%), and Sc₂O₃ (up to 1.90 wt%). Malayaite is close to the pure Sn end-member, it contains up to 97 mol% Sn end-member with minor Fe, Nb, Ta contents. Stokesite, CaSnSi₃O₉·2H₂O, occurs as a rim grown around the outermost parts of Sn-rich titanite crystals, veinlets cutting cassiterite, and in direct contact with fluorite. Its crystals were also observed on surfaces or within fractures in bismuthinite.

The initial source of Sn was related to the final stage of pneumatolytic processes, in the granitic complex with successive development during hydrothermal activity. Fluid inclusion studies indicate that cassiterite crystalized at temperatures of 515–470ºC (Kozłowski et al., 2002).

The precipitation of Sn-rich titanite was likely initiated under elevated metal activities at slightly lower temperatures and high oxygen fugacity.

Stokesite, representing the final stage of the Sn assemblage, slowly crystallized in free spaces, was found in a direct contact with fluorite, which homogenization temperature in the Szklarska Poręba assemblage was estimated at 159-172 ^oC (Kozłowski & Matyszczak, 2022). Therefore, stokesite and fluorite may have formed during the same stage of hydrothermal processes. Since no alterations had been observed on the cassiterite grains, a secondary source of tin for later Sn-rich minerals was excluded.

How to cite: Mil, K., Gołębiowska, B., Włodek, A., and Pieczka, A.: Tin mineralization in post-magmatic processes: a case of post-magmatic activity in the Szklarska Poręba Huta quarry, Lower Silesia, SW Poland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-764, https://doi.org/10.5194/egusphere-egu24-764, 2024.

The volcanic landscapes of Iceland's Westfjords are marked by the intriguing presence of Plagioclase Ultraphyric Basalts (PUBs), distinctive lava formations that are a focal point of this research. Characterized by plagioclase contents so high (up to 50-60%) that they approach the crystallinity of a crystal mush, these formations offer a unique opportunity to explore the extreme end of lava crystallinity and the influence of abundant large plagioclase crystals on lava viscosity and flow. The main aim of this research is to understand how the abundance of large plagioclase crystals influences the viscosity and flow of lavas at the extreme end of lava crystallinity, as well as better understand the origin of the crystal cargo. The interplay between the crystals and the magma is crucial for better understanding the origins and flow characteristics of these volcanic formations. This is achieved through an interdisciplinary approach, combining petrographical and geochemical analyses, including Inductively Coupled Plasma (ICP) for major element trace element analysis, with Anisotropy of Magnetic Susceptibility (AMS) to determine the flow direction within the lava. This comprehensive method provides insights into the crystallization conditions of magmas and minerals, as well as the textural and compositional characteristics of the plagioclase crystals. The outcomes of this research are not only crucial for understanding the unique aspects of the Westfjords’ volcanic regions but also have significant implications for predicting volcanic hazards and refining magma dynamics models, thereby enhancing our ability to mitigate the impacts of volcanic activity.

How to cite: Jones, P., Caracciolo, A., Marshall, E. W., and Piispa, E. J.: Understanding the flow dynamics of a Plagioclase Ultraphyric Basalt- a case study from the Westfjords, Iceland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1209, https://doi.org/10.5194/egusphere-egu24-1209, 2024.

The study of iron-magnesium silicates within rocky planetary interiors has been a cornerstone of mineralogy, petrology and planetary science, offering insights into the composition and evolution of celestial bodies. The talk will present an exploration of the current understanding of these silicates and critically examines the question: Have we truly discovered them all?

Recent advancements in analytical techniques, including high-pressure experiments and computations, have challenged conventional assumptions about the ubiquity and diversity of iron-magnesium silicates. During the talk, key discoveries on Earth, Mars, and other celestial bodies will be reviewed revealing unexpected mineralogical variations and prompting a reevaluation of existing models.

How to cite: Bindi, L.: Iron-magnesium silicates in rocky planetary interiors: Have we really discovered them all?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1725, https://doi.org/10.5194/egusphere-egu24-1725, 2024.

Rare earth elements (REE) are essential in many green, modern technologies and play a critical role in a more sustainable future [1]. However, there is a substantial risk to their supply as the availability of REE deposits with minable concentrations are limited [2]. A better understanding of the mechanisms controlling REE concentration in minerals would have applications in more efficient practices as well as REE separation techniques and recycling.

Our study investigated the reaction of multi-component REE (La, Ce, Pr, Nd, and Dy) aqueous solutions with carbonate grains of dolomite, aragonite and calcite at hydrothermal conditions (21-210 °C). Two different solutions were prepared (i) a solution with equal concentrations of each of the five REE: (ii) a solution with the concentrations of the five REEs normalized to a Post Archean Shale standard (PAAS), to mimic the rare earth element concentrations in continental crust and natural fluids.

The interaction between the REE bearing fluids with each of the carbonate grains resulted in the replacement of the host carbonate grain with a series of REE minerals following a complex crystallization sequence (lanthanite → kozoite → bastnasite → cerianite). We have found that for most of the experiments at 165 °C, when using the equal concentration solutions, the crystallization of kozoite was promoted and the REE ratio in the newly formed solids was similar to the REE ratio in solution. In contrast, when PAAS solutions were used, REE-bearing crystals were zoned or had a heterogenous distribution of REEs, often coupled with the formation of discreet REE phases (e.g., cerianite). In addition, chemical signatures indicating the presence of metastable REE-bearing phases that transformed to more thermodynamically stable polymorphs were found in multiple samples as well as symplectite textures formed by the reaction of adjacent phases. Overall, our experiments demonstrate that the polymorph selection, crystallization pathway, the kinetics of mineral formation and the chemical texture of the newly formed rock during the mineral-fluid interaction process are dependent on the REE concentrations in solution, their ionic radii, temperature, time, and solubility of the host grains.

References

[1] Sinding-Larsen, R., Wellmer, F.W.,. Non-renewable resource issues: Geoscientific and societal challenges, Non-Renewable Resource Issues: Geoscientific and Societal Challenges 2012.

[2] Jordens, A., Cheng, Y.P., Waters, K.E.,. A review of the beneficiation of rare earth element bearing minerals. Miner. 2013 Eng. 41, 97-114.

How to cite: Maddin, M., Rateau, R., Szucs, A. M., Terribli, L., and Rodriguez-Blanco, J. D.: Complex Multi-Stage Replacement Reactions in the REE-CaCO3 System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2001, https://doi.org/10.5194/egusphere-egu24-2001, 2024.

Charnockite is an orthopyroxene-bearing felsic rock and an important constituent of the deep crust, thus, it holds significant importance in uncovering crustal growth and differentiation mechanisms. However, its generation and preservation remain debated. By focusing on mineral records, we here aim to provide a more detailed understanding of these issues. The Gaozhou charnockite in the Yunkai terrane of South China was chosen for extensive mineralogical studies and thermodynamic modeling. The Gaozhou charnockite contains granulitic enclaves, and mineral assemblages within charnockite can be divided into three phases, with the peak phase mainly composed of orthopyroxene, and minor biotite. Meanwhile, the charnockite and enclaves show comparable compositions of biotite and orthopyroxene. Embayed textures and high TiO₂ content in biotite grains suggest high-temperature anatexis. On the other hand, the orthopyroxenes with inclusions and high Al₂O₃ content indicate peritectic origin. Moreover, reaction intergrowths of biotite with orthopyroxene grains have also been observed, suggesting that these grains were generated by the consumption of biotite. The Gaozhou charnockite has much lower zircon water content (135 ppm, median) as compared to that of the contemporary Opx-free granites (202-643 ppm, medians) in the Yunkai terrane, indicating dry primary parental melts. In addition, phase equilibria modeling constraints peak anatexis conditions at 860-870 ℃/6.2-7.0 kbar. Peritectic orthopyroxenes must have been generated by the incongruent melting of biotite under high-temperature granulitic facies in the lower crust. Subsequently, these grains were entrained and migrated by low water content melts to the upper crust. Therefore, overall observations favor a model of selective entrainment of source materials at a low magma water environment for the generation of the Gaozhou charnockite.

How to cite: yang, H. and Yao, J.: Generation of the charnockite by residua entrainment in water-deficient melts: insights from minerals composition and H2O-in-zircon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2231, https://doi.org/10.5194/egusphere-egu24-2231, 2024.

Quartz, the most common mineral constituent of the Earth’s continental crust, undergoes the displacive α-β transformation at pressures and temperatures of the lower crustal conditions. This transition is associated with important variations in the thermodynamic properties (such as thermal expansion and isothermal bulk modulus) and is therefore thought to cause important seismic velocity contrasts that are distinguished by seismic tomography. The α-β transition is characterized by a non-linear increase in volume with temperature and an abrupt variation in bulk modulus, which, at the transition, drops from about 70 GPa to nearly zero within 10-15 K. Although well-known at room pressure, the behavior of quartz across the transition at high pressure, i.e., at Earth-relevant conditions, remains largely unexplored.

In this work, we have characterized this transition at high P-T conditions by means of X-ray diffraction and acoustic measurements. The experiments were performed at the European Synchrotron Radiation Facility (ESRF, beamline ID06) using a multi anvil press up to 3 GPa and 1400 °C. The measured velocities show a strong decrease of V_p toward the phase transition, followed by a steep increase in the β-field, reaching values higher than those in the α-field. In our data, this increase is not as large as that predicted by thermodynamic models using the known elastic properties of quartz (e.g., Abers and Hacker 2016). As anticipated, V_s is rather constant throughout the transition, resulting in major variations in the V_p/V_s ratio. The unit cell volume was calculated from the collected diffraction patterns. Contrary to the well-documented negative thermal expansion of quartz in the β-field at room pressure, the unit cell volumes obtained at high-pressure show a slight continuous volume increase during heating after the phase transition.

In conclusion, we document here that the behaviour of quartz across the α-β transition at high P-T is different from what has been previously predicted, which is likely a consequence of the poor knowledge of β-quartz thermo-elastic properties at high P-T. This could affect the interpretation of seismic data in the deep crust, which is currently based on extrapolations of the room-pressure behavior of the α-β quartz transition.

How to cite: Mingardi, G., Gasc, J., Ardit, M., Alvaro, M., and Schubnel, A.: What can we learn from X-ray diffraction and seismic velocities across the alpha-beta quartz transition at lower crust conditions? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2301, https://doi.org/10.5194/egusphere-egu24-2301, 2024.

In order to explore the favorable reservoir characteristics and diagenetic evolution laws of the Cretaceous Kukebai Formation in the Kekeya area of the southwestern Tarim Basin, and provide theoretical basis for oil and gas exploration and development in the study area, comprehensive data such as core, cast thin sections, and carbon and oxygen isotopes were used to carry out the classification of diagenetic facies types and the study of diagenetic evolution models. The results indicate that the reservoir of the Kukebai Formation in the study area is mainly composed of feldspar lithic sandstone and lithic feldspar sandstone, with mainly developed diagenetic processes such as compaction, cementation, and dissolution. The diagenetic stage is in the middle diagenetic stage A. The Kukebai Formation reservoir mainly develops four types of diagenetic facies: moderately compacted dissolution facies, moderately compacted cementation facies, strongly compacted compaction facies, and strongly cemented facies. Among them, the strong compacted phase becomes a dense reservoir due to mechanical compaction in the early stage of diagenesis, and is mainly distributed in the sand mud interbedded layers of sedimentary microfacies between river channels and estuarine dams; The strongly cemented phase is densified in the early diagenetic stage due to the precipitation of a large amount of carbonate cement, mainly developed in the sand mud interbedded layers near the mud end of underwater distributary channels and the sedimentary microfacies of estuarine dams; The dissolution effect of medium compacted dissolution phase sandstone is strong, and the reservoir properties are the best, mostly appearing in the upper part of distributary channel sand bodies with strong sedimentation and water accumulation dynamics; The medium compacted and cemented sandstone has moderate compaction, and the reservoir properties are relatively good. It mainly develops in the lower part of distributary channel sand bodies with strong hydrodynamics. There are two types of favorable reservoirs in the study area, namely the medium compacted cementation phase and the medium compacted dissolution phase sandstone.

How to cite: Wang, H. and Zhang, L.: Reservoir characteristics and diagenetic evolution of Kukebai Formation in Kekeya area, Southwest Depression of Tarim Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2730, https://doi.org/10.5194/egusphere-egu24-2730, 2024.

Serpentines are among the most abundant hydrous minerals in oceanic lithospheres formed by hydrothermal alteration of ultramafic mantle rocks (i.e. peridotites). Antigorite – the high temperature and pressure variety of serpentine – is considered to be the dominant water carrier within down-going oceanic slabs. The successive dehydration of antigorite during subduction of partially serpentinized oceanic lithospheres is strongly associated with the water cycle in the upper mantle and is expected to play an important role in the generation of arc magmatism (Ulmer & Trommsdorff, 1995; Schmidt & Poli, 1998), and influence rheological properties of oceanic slabs by processes such as dehydration embrittlement which is thought to trigger intermediate-to-deep focus earthquakes (Jung et al., 2004; Ferrand et al., 2017).

Antigorite is a hydrous phyllosilicate known for its polysomatism: The number of SiO₄ tetrahedra m along its a-cell periodicity. Previous electron microscopy studies reported the existence of antigorite within a wide range of m values (~13-23) depending on the pressure (P) and temperature (T) conditions (Mellini et al., 1987; Wunder et al., 2001). However, there is a lack of the combined structural and thermodynamic evidence about the stability of the different antigorite polysomes along the P,T-paths of subducting oceanic lithospheres.

We use a theoretical mineral physics approach based on first principles density functional theory calculations to quantify the phase diagrams of the terminal dehydration reactions of antigorite with different m-values between 13-19 under subarc depth P,T conditions. Our results elucidate the significance of the compositional variations of antigorite on the dehydration of serpentinized oceanic slabs during the progressive stages of subduction.

How to cite: Ritterbex, S. and Plümper, O.: First principles investigation of the effect of compositional variations on the terminal breakdown of antigorite in subduction zones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2878, https://doi.org/10.5194/egusphere-egu24-2878, 2024.

In November 2023, the European Union reached a provisional agreement on an European Critical Raw Materials Act, which encourages the local production, processing, and recycling of critical elements, notably the rare earth elements (REE). While indispensable for the green energy transition, their production is notoriously environmentally damaging, and efforts are being made to reduce this environmental footprint, for example via the use of secondary REE sources from waste or by the application of green chemistry and circular economy principles.

In this study, we investigated the potential of hen eggshell calcite waste to be recycled for the uptake of REE from industrial and waste streams. We interacted commercial eggshells with 50 mM multi-REE (La, Nd, Dy) solutions at 25 to 205 °C between three hours and three months. The resulting products were characterized by powder XRD and Rietveld refinement for quantitative phase identification; SEM electron imaging for structural characterization; SEM energy dispersive spectroscopy for elemental mapping and quantification of major and minor elements; and laser ablation ICP-MS for trace element mapping.

We observe a pervasive diffusion of the REE inside the eggshell calcite, along pathways formed by the intracrystalline organic matrix and calcite crystal boundaries, and without any partitioning of La, Nd and Dy. At 90 °C, calcite is observed dissolving and being replaced by kozoite spherulites, reminiscent of natural kozoite crystals. At 165 °C and 205 °C, an interface coupled dissolution-precipitation mechanism is observed, resulting in the complete dissolution of the calcite and its pseudomorphic replacement by polycrystalline kozoite. At 205 °C, kozoite itself is slowly replaced by hydroxylbastnäsite, the stable form of rare earth hydroxycarbonate, following a crystallization pathway previously established with inorganic calcite. Minor REE zoning at the eggshell grain scale is also observed, hinting at a potential use for REE separation.

Our results demonstrate two potential applications of eggshell waste for the sustainable recovery of REE from aqueous solutions: at low temperatures, as a mixed organic-inorganic adsorbent and absorbent; and at higher temperatures as an efficient sacrificial template for the precipitation of rare earth hydroxycarbonates.

How to cite: Rateau, R., Drost, K., Maddin, M., Szucs, A., Terribili, L., Guyett, P., and Rodriguez-Blanco, J. D.: Sustainable recovery of rare earth elements with eggshell waste calcite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2915, https://doi.org/10.5194/egusphere-egu24-2915, 2024.

The interactions between clay minerals and organic matter, specifically adsorption, are widely recognized as a crucial mechanism for promoting the preservation of organic matter within sedimentary environments. This paper discusses the genesis and adsorption of clay minerals, especially their influence on the process of organic matter enrichment in sedimentary environments. The composition of clay minerals found in sediments serves as an indicator of both the climatic and lithological characteristics of the provenance area. Smectite formation is favored in mafic provenance, while the coexistence of illite and chlorite suggests cold and arid conditions. Additionally, an abundance of kaolinite indicates intense chemical weathering of the provenance area. The physical and chemical properties of clay minerals and organic matter significantly influence adsorption. Smectite is thought to adsorb more organic matter due to its greater surface area. Selective adsorption of high molecular weight, aromatic, and aliphatic compounds dissolved organic matter onto mineral surfaces may have played a role in kerogen formation. Moreover, the preservation of organic matter via clay mineral adsorption is intricately linked to the sedimentary environment. Disparities in nutrient elements during the clay minerals synsedimentary period can impact biological productivity. Furthermore, the pH and solution metal ions of the water column influence the quantity and type of organic matter adsorbed. The contribution of adsorption to organic matter preservation is influenced by redox conditions, and this contribution can be observed through density separations. Additionally, we present several recommendations for future research. Firstly, diagenesis alters the clay mineral assemblage in sedimentary rocks. However, it may be possible to reconstruct the clay mineral assemblage based on morphological, mineralogical, and chemical composition characteristics. Secondly, studies have indicated that clay minerals can facilitate the precipitation of carbonate minerals, providing insights into the formation of abiotic carbonate minerals. Finally, the practical applications of clay minerals in shale oil and gas exploration are underscored, such as their ability to predict sweet-spot areas and control reservoir properties.

How to cite: Zhao, T., Xu, S., and Gou, Q.: Differential adsorption of clay minerals: Implications for organic matter enrichment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3030, https://doi.org/10.5194/egusphere-egu24-3030, 2024.

Concrete is one of the most sought-after materials in our time, second only to water in importance to developed and emerging nations alike. It has been a crucial component of major infrastructure projects for thousands of years. In the year 2022 alone, China, the largest producer of concrete, manufactured approximately 2.1 million metric tons of cement, a key ingredient in modern concrete formulations. Various concrete mixes, tailored for specific applications, have been perfected and are widely used in the industry. In broad terms, concrete consists of about three-fifths sand and rock fragments (aggregates), one-fifth cement, and one-fifth water. This combination makes it the world's most widely used building material, particularly for large structures which are reinforced with steel rods. Aggregates can be sourced from crushed rock or naturally occurring sand and gravel, but the type of aggregate used significantly influences the overall properties and robustness of the final product. The mineralogical composition of the rock itself is closely related to the quality and resilience of the concrete. Understanding the mineralogy and chemistry of the lithotypes used allows for predicting their interaction with other concrete constituents, preventing undesirable chemical reactions. Such reactions can compromise the safety and resilience of the finished product, and ultimately prevent the use of materials that would otherwise perform poorly. Among the many concrete pathologies that may arise from the use of inadequate raw materials, internal sulfate attack (ISA) mainly occurs when sulfide-bearing aggregates are used. This leads to complex chemical reactions resulting in the oxidation of sulfide phases and the release of sulfur into the cement paste. Consequently, severe cracking and internal swelling significantly compromise concrete integrity. The European standard (EN 12620:2008) is a widely used guideline that recommends a total sulfur content in aggregates not exceeding 1.0 wt.%. This threshold is reduced to 0.1 wt.% when pyrrhotite is detected in the lithotype to be used as an aggregate. Given that pyrrhotite is the second most common sulfide found in nature, it is crucial to identify and quantify the various sulfide minerals that may be present and to understand how they can affect finished concrete structures. The use of automated mineralogy, represented by software systems such as QEMSCAN, emerges as a powerful solution for identifying and quantifying pyrrhotite and any other sulfide phases in aggregates for concrete. It is a scanning electron microscope (SEM)-based system that uses backscattered electron (BSE) image segmentation and simultaneous acquisition of energy-dispersive X-ray (EDS) spectra to classify mineral phases using a pre-defined list of mineral spectra. Preliminary results from QEMSCAN analysis of both thin sections and mounts comprised of ground rock of different grain sizes have been promising. This SEM-based system can analyze whole rock samples and crushed aggregates, providing accurate results over different size intervals. Despite the expected negative correlation between sample grain size and pyrrhotite content, the results vary from 2.71 to 5.59 wt.% for total pyrrhotite content in the analyzed samples. Moreover, when averaged over all grain sizes, these results align with those obtained through traditional optical petrography.

How to cite: Titon, B., Duchesne, J., and Fournier, B.: Use of automated mineralogy for the quantification of pyrrhotite in concrete aggregates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4169, https://doi.org/10.5194/egusphere-egu24-4169, 2024.

Introduction:  Hydrated silica has been detected from orbit in Jezero crater [Tarnas et al., 2019] and holds great promise for the astrobiology science goals of the M2020 mission and the MSR Program. Early entombment within an hydrated silica matrix has been shown to minimize the molecular degradation of microorganisms during advanced diagenesis [Alleon et al., 2016a,b; Alleon et al., 2018].

On sol 0910, a float rock was automatically selected by the AEGIS system after a rover drive when entering the margin unit from the Jezero delta top. The target is a light-toned partially buried float with lustrous appearance.

LIBS: The chemistry of 9/10 points reveal a homogeneous composition, enriched in SiO₂. The average SiO₂ for these 9 points is 75.0 wt.% while the average total of quantified oxides is 83.5 wt. %.  

VISIR reflectance: The reflectance spectra share an overall blue slope, and exhibit absorptions at 1.9 µm (H₂O), 2.2 µm (X-OH) and 1.4 µm (OH & H₂O). The chemistry derived from LIBS (mean Al₂O₃< 2 wt.%) leads to the attribution of the 2.2 µm band to Si-OH. All such absorptions are present within spectra of terrestrial hydrated silica.

What type of hydrated silica? The reflectance spectra show that this target contains both Si-OH and molecular water. The position of absorption bands departs from what is typically observed for opals and chalcedony is at present the closest spectral analogue in term of band depths and position.

What origin? A 2.2 µm band has been observed in the IR spectra from the fan top and the margin unit, together with carbonate signatures. The LIBS derived chemistry of the targets suggest that this 2.2 band is related to hydrated silica. This suggests that the formation of the hydrated silica is associated with carbonate formation (locally or in the catchment) and that AEGIS_0910A may have the same origin. One possible scenario that is being investigated is that this silica material could represent the precipitates from a fluid that dissolved the ubiquitous olivine found in Jezero floor and delta, and concomitantly precipitated carbonates that are abundant in delta-rocks and the marginal unit ([Calvé et al., LPSC 2024; Wiens et al., LPSC 2024]).

Here, IR spectroscopy reveals that this hydrated silica-rich material is more crystalline that the hydrated silica deposits previously reported on Mars from orbit and in situ at Marias Pass, Gale crater [Pan et al., 2021; Gabriel et al., 2022; Ruff et al., 2011; Rapin et al., 2018].

Summary: Two independent lines of evidence, IR and LIBS, reveal that the float rock analyzed on sol 910 is made of hydrated silica. This target is unique so far in the SuperCam dataset (> 500 targets), but may be linked to high SiO₂ points observed in the carbonate-rich delta bedrock units. Based on IR, this rock seems more akin to a micro-crystalline type silica, in contrast to previous observations of silica from the ground. Such a target may have trapped and preserved biosignatures, together with unique information on the paleoenvironmental conditions of the Jezero crater.

How to cite: Beck, P. and the Supercam and M2020 team members: Multi-spectroscopic detections of hydrated-silica in the Jezero crater   , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4623, https://doi.org/10.5194/egusphere-egu24-4623, 2024.

Greenhouse gases, especially CO₂, have been increasing worldwide. To address this issue, carbon capture and storage (CCS) technology has been researched and developed to decrease atmospheric CO₂ concentrations. Among the various methods studied, mineral carbonation is an emerging technique that involves the reaction between Ca-Mg-Fe bearing basaltic rocks and CO₂ to store it in the rocks through the formation of carbonate minerals. The CarbFix project in Iceland is an example of this method. However, there is still much to learn about the physicochemical relationships between water, dissolved ions, and growing crystals in complex multicomponent systems at the atomic and nanoscale, which are essential for the successful implementation of CCS in basaltic reservoirs.

One of the methods being explored in this study involves the utilization of supercritical CO₂, which is achieved above the critical temperature and pressure of 30.97 °C and 73.773 bar, respectively. Under these conditions, CO₂ exhibits both liquid and gaseous properties. This work shows the results of an experiment conducted in basaltic crystals and basaltic glasses at the temperature and pressure range of 100 and 200 ºC, and 64 to 79 bar, to investigate the reaction between CO_2(sc), water, natural forsterite and basaltic glass, which have demonstrated that under these conditions we have the partial dissolution of the previous mineralogical phases, and the subsequent formation of new alteration phases, but also the precipitation of carbonates with Ca, Mg and Fe. We will compare our results with studies of carbonation of synthetic forsterite.  

How to cite: Pierozzi, A., Rateau, R., Orlando, A., Borrini, D., and Rodriguez Blanco, J. D.: Carbonation experiment of basaltic crystals and glasses using supercritical CO2 under different PT conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4658, https://doi.org/10.5194/egusphere-egu24-4658, 2024.

Fluocerite is a rare earth element (REE) fluoride mineral with chemical formula (REE)F₃. It is found in nature as an accessory mineral in magmatic-hydrothermal REE ore deposits, including alkaline complexes and carbonatites, where is associated with REE fluorocarbonates (i.e. bastnasite, parisite, synchysite), REE-bearing fluorite, cerianite, monazite and xenotime. Due to its relatively scarcity in these deposits, fluocerite kinetics and mechanisms of crystallisation, its role in REE fractionation and as phase for the evolution of magmatic-hydrothermal REE mineralizing systems have not received a lot of attention in the past years. Recently instead, fluocerite is gaining interest as it was suggested to be a precursor phase of bastnasite. Bastnasite is one of the most important minerals for the extraction of REE, indispensable in modern world because of their wide range of hi-tech industry and in clean energy applications. For this reason, illuminating the mechanisms of fluocerite crystallization and its role in the evolution of REE deposits could significantly enhance our understanding of the genesis of REE fluorocarbonates. 
The present study has two main objectives: 1) To study the kinetics and mechanisms of the fluocerite formation at temperatures ranging from ambient to low hydrothermal (up to 200 °C) 2) To demonstrate in situ that fluocerite reacting in the presence of a CO₃-rich solution can transform into REE fluorocarbonates in hydrothermal conditions. 
For the first purpose, fluocerite was synthesized by reacting pure fluorite (CaF₂) powder with REE-bearing solutions at different temperatures. To achieve the second objective, synthetic fluocerite was reacted with Na₂CO₃ solutions at hydrothermal conditions up to 200 °C. Samples of solids were taken at specific time intervals to follow the ongoing of the crystallisation reactions. The nature of crystallising solids, their quantification and growth morphology were determined with a combination of powder X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive microscopy (SEM-EDS).
Our results showed that the fluocerite crystallisation rate decreases proportionally with the REE atomic number and increases with increasing T. The activation energy of crystallisation is similar irrespective of the REE used in the synthesis (~75 KJ/mol) while the activation energy of nucleation increases with the REE atomic number (80 - 96 KJ/mol). All fluocerites reacted with the CO₃-bearing solutions transformed into bastnasite at all temperature, also forming cerianite in the Ce-bearing experiments. 

How to cite: Terribili, L. and Rodriguez-Blanco, J. D.: Mechanistic insights into the fluorite-fluocerite-bastnasite transformation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4694, https://doi.org/10.5194/egusphere-egu24-4694, 2024.

Mineral replacement reactions are essential for the understanding of the genesis and chemistry of REE-bearing carbonatite deposits. Many of these reactions involve interaction of Ca-Mg and REE carbonate phases, leading to the formation of minerals with complex compositions and structures.

This study explores the oriented surface precipitation of REE carbonates during the interaction of individual and multiple REE-bearing aqueous solutions with calcite and aragonite (CaCO₃) at low hydrothermal conditions (25-220 °C). This mineral-fluid interaction is translated into a temperature-dependent solvent-mediated surface precipitation and subsequent pseudomorphic mineral replacement of the CaCO₃ seeds by newly formed REE carbonates. This complex replacement sequence includes the crystallisation of metastable kozoite (orthorhombic REECO₃OH) via the formation of individual spindle-shaped crystals following a transient non-random orientation on the surface of the host grains, gradually covering their full surfaces.

Our experiments show that the likelihood of formation of the oriented overgrowth and its stability are controlled by structural constraints which in turn depend on four factors: temperature, ionic radii and ionic potential of the REE in the system, and dissolution rate of the host CaCO₃ minerals. Also, we demonstrate that REE elements can be rapidly immobilized as REE hydroxicarbonates, even at low hydrothermal conditions. An explanation of the epitaxial overgrowth’s configuration and the atomic arrangement of the structures of the CaCO3 polymorphs and REE-kozoite will be discussed. 

[1] Szucs AM et al. Reaction Pathways toward the Formation of Bastnäsite: Replacement of Calcite by Rare Earth Carbonates. Crystal Growth & Design, 2021;21(1):512–527.
[2] Szucs AM et al. Targeted Crystallization of Rare Earth Carbonate Polymorphs at Hydrothermal Conditions via Mineral Replacement Reactions. Global Challenges. 2022;2200085.

How to cite: Rodriguez-Blanco, J., Szucs, A. M., Rateau, R., Maddin, M., and Terribili, L.: Temporal growth of epitaxial layers in the CaCO3-REECO3OH system during mineral replacement processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4776, https://doi.org/10.5194/egusphere-egu24-4776, 2024.

Omphacitic clinopyroxenes exhibit widespread occurrence in various geological settings and rock types, making them promising candidates for Raman elastic geothermobarometry applications. Raman elastic geobarometry uses the deformation recorded by mineral inclusions to determine the pressure and temperature conditions under which they were entrapped. Raman scattering, which is highly sensitive to structural deformations, provides valuable insights into the variations in crystal structure that occur due to heating or compression. While several host-inclusion systems have been investigated, clinopyroxene inclusions have not been extensively studied. Therefore, the application of Raman elastic geobarometry to omphacites in different mineral hosts necessitates an accurate calibration of Raman-peak positions against hydrostatic pressure.

Natural omphacite crystals can exhibit cationic ordering associated with crystallization temperature, which affects their elastic behaviour. To address these aspects, we conducted a study on natural ordered (P2/n) and experimentally disordered (C2/c) omphacite crystals from Münchberg Massif (Germany). In situ high-pressure Raman spectroscopy measurements were performed using a diamond anvil cell. As expected, the frequencies of the modes increased with increasing pressure. By examining omphacite crystals with varying degrees of order obtained through isothermal annealing experiments, we observed that progressive cationic disorder primarily led to peak broadening, while changes in Raman peak positions were predominantly influenced by pressure variations.

Additionally, the chemical composition of omphacites influences the Raman-peak positions and their pressure evolution. Therefore, we analysed Fe³⁺-rich omphacites from Lugros and Camarate (Bétic Cordilleras, SE Spain), and Voltri (Italy) along with synthetic iron-free omphacites. This analysis is an initial step towards the chemical calibration of omphacites using Raman spectroscopy.

To gain a deeper understanding of the elastic behaviour of modes suitable for elastic geobarometry, we simulated the Raman spectrum of a fully ordered omphacite (Jd₅₀Di₅₀ composition) at different pressures using ab initio Hartree-Fock/Density Functional Theory simulations. The simulated data exhibited excellent agreement with experimental spectra, enabling us to comprehend the pressure dependence of specific modes. Leveraging these findings, we can calculate the entrapment pressure of omphacite inclusions still confined within their host rocks by determining Raman shifts of the main peaks alongside changes in cation order.

Our results provide valuable insights into the calibration and application of Raman elastic geobarometry for omphacitic clinopyroxenes. By considering the influence of chemical composition and cationic ordering, we have enhanced our understanding of the elastic behaviour of omphacite and its potential for geobarometric calculations. These findings offer a valuable tool for determining the pressure and temperature conditions of geological processes involving omphacitic clinopyroxenes.

How to cite: Baratelli, L., Mihailova, B., Prencipe, M., Cámara, F., and Alvaro, M.: Raman elastic geobarometry: investigating cation order in omphacitic clinopyroxenes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5885, https://doi.org/10.5194/egusphere-egu24-5885, 2024.

Abstract

Functional groups (e.g. alcohol, hydroxyl, carboxyl etc.) of soil organic matter are responsible for soil properties like cation exchange capacity or wettability. Functional groups can be characterized by spectroscopic procedures like Fourier transform infrared (FTIR) spectroscopy since the infrared light can introduce vibration modes within the groups. Only the light of an energy similar to the bonding energy of the C=O bond, for example, causes the absorption bands of the functional groups to show up at typical wavenumber (WN) regions in FTIR spectra. However, when the C=O group interacts with cations, the bonding energy may change thereby affecting the WN region of the absorption band. This change in WN (following organic matter (OM)-cation interaction) may limit procedures of automated spectral interpretation, which are mostly based on fixed ranges -determined from textbooks, or sets of single wave numbers determined by statistical approaches.

Our study aims to quantify the effect of OM-cation interactions on the spectral features (intensity and WN region of C=O absorption bands) in FTIR spectra. To quantify the effect of OM-cation interactions on defined functional groups as far as possible, we study mixtures of polygalacturonic acid (PGA; as a model substance for soil organic matter) with different polyvalent cations (Ca²⁺, Fe^³+, Al^³+) at different concentrations.

PGA-cation mixtures with different cation concentrations were prepared, freeze dried, and characterized using FTIR spectroscopy (KBr technique). A proton-cation exchange at the carboxylic acid groups during PGA-Cation interaction gives rise to a COO- band in FTIR. Since the cation effect is found in an earlier study to be stronger for the COO- band (1620-1550 cm^-1) as compared to the C=O band, the interpretation of the FTIR spectra focuses on the COO- band. Compared to spectra of pure PGA, the spectra of all PGA-cation mixtures show a significant positive correlation between COO- band intensity and cation concentration. Additionally, a shift in the maximum of COO- band towards lower WN was observed for all cations, which depends on the kind of cations and increased with cation concentration.

Increase in intensity of the COO- band and the shift in WN region of COO- band maxima confirms changes in FTIR spectral features with cation addition and that those changes depend on the type of cation. The results suggest that type and concentration of cation should be considered when interpreting FTIR spectra of organic matter since both, change in intensity and shift in the WN of the band maxima, could restrict procedures of automated spectral interpretation, which mostly rely on fixed ranges (from textbooks), or sets of single wave numbers determined by statistical approaches. For a deeper understanding on the relation between OM-cation interactions, organic matter with increasing heterogeneity and complexity need to be studied.

How to cite: Bhattarai, N. and Ellerbrock, R. H.: Spectral characterization of organic matter is affected by polyvalent cations interaction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5906, https://doi.org/10.5194/egusphere-egu24-5906, 2024.

Constant development of high and green technologies makes rare earth elements (REE) more viable than ever. Relative scarcity of REE and lack of proper substitutes increase the demand for inexpensive and efficient methods of their recovery. Some new methods and technologies have been already proposed but their effectiveness leaves much to be desired. Most recently, precipitation in form of lead apatite has been proven to provide with very high levels of REE removal from aqueous solutions.

Substitution of REE in apatites has been broadly studied for calcium–phosphate apatite specimens, while lead–phosphates have been usually omitted. Recent studies suggested that precipitation of Pb and individual REE, induced by the presence of phosphates and Cl ions, results in near complete removal of cations from solutions in the form of REE-containing pyromorphite Pb₅(PO₄)₃Cl. The goal of this study was to optimize the procedure. 

Pyromorphite (Pym) was precipitated from a solution of phosphoric acid (1:1) containing REE (each element at the concentration of 15 ppm) by addition of NaCl and Pb(NO₃)₂ (powder). The addition was conducted 5 times with very small amount of Pb relative to phosphates: 1/200, 1/100, 1/50, 1/20 and 1/10 of Pb needed for complete reaction with phosphoric acid. The amount of Cl was used in 1.5 times excess with respect to stoichiometric Pb. Each time solids and solutions were separated and sampled for the analysis.

The synthesis was carried out under atmospheric pressure, at an ambient temperature of about 21°C and at pH=3. Powder X-ray diffraction (XRPD) was used to identify the obtained phases, scanning electron microscopy (SEM) to examine the morphology of the crystals, energy-dispersive X-ray spectroscopy (EDS) for analysis of the elemental composition of solids, while solutions were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-OES).

Most REE are removed already at the first, lowest dose of Pb: more than 99% of La, Ce, Pr, Nd, Sm, Eu, and Gd; between 90 and 96% of Tb, Dy, Ho, and Er; between 80 and 50% of Tm, Yb, and Lu; 46% of Sc, 86% of Y, and 98% of Th disappear from the solution. After the third addition, REE are removed completely (except for Sc, which required 5 amendments). All these elements were removed from solution by precipitation of REE-containing Pym. An admixture of "phosphoschultenite" PbHPO₄ also appears in the precipitate, which most likely does not contain REE (or contains much less than Pym).

These preliminary results indicate strong affinity of REE with Pym structure. In contrast to previous findings (Sordyl et al., 2023), a fractionation of REE was observed. Further analyses are in demand for better understanding of the mechanism of these processes which will allow for optimization of industrial applications.

This research was funded by National Science Centre research grant no. 2021/43/O/ST10/01282.

References:

Sordyl, J., Staszel, K., Leś, M., & Manecki, M. (2023). Removal of REE and Th from solution by co-precipitation with Pb-phosphates. Applied Geochemistry, 158, 105780. https://doi.org/10.1016/j.apgeochem.2023.105780

How to cite: Staszel, K. and Manecki, M.: First evidence of strong REE compatibility with pyromorphite Pb5(PO4)3Cl, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8290, https://doi.org/10.5194/egusphere-egu24-8290, 2024.

The NASA Perseverance rover is exploring Jezero crater on Mars since february 2021 [1]. Perseverance’s main goal is to investigate the past geologic and environmental conditions of Jezero crater and seek evidence of past life. For this, the rover has characterized the local geology of the crater floor and is presently working in an ancient river delta. Then, Perseverance will explore the crater rim, and possibly some regions outside of the crater. In addition, the rover selects and collects the most compelling samples that will be retrieved and brought back to Earth by a future mission (NASA/ESA Mars Sample Return project) for more detailed study.

Perseverance uses a panel of spectroscopic tools based on the analysis of sunlight reflectance in the visible and near-infrared domains (MastcamZ, SuperCam), deep-UV (SHERLOC) and time-resolved (SuperCam) Raman, Laser Induced Breakdown Spectroscopy - LIBS (SuperCam) and X-ray fluorescence (PIXL). Some instruments can analyze the chemistry and mineralogy of rocks remotely up to several meters [2-3] while others work close to the rock for higher spatial resolution (~100 mm) and better textural control [4-5]. The rover is operated nearly every day and sends data almost immediately to Earth.

On the crater floor, Perseverance found igneous rocks: basaltic lava or pyroclastic flows [6] covering an olivine-rich cumulate [4,7]. The magmatic mineral assemblage, including the textural relationships, was carefully described: mostly Fe-rich pyroxenes in the basaltic flows, and a cumulate composed of dominant olivine with augite and pigeonite, as well as some phosphates and (Cr-)Ti-Fe-oxides in both units. The bulk of these rocks is weakly altered but Fe-Mg carbonates [8], sulfates [5] and various phyllosilicates [9] were detected showing that fluid-rock interactions locally occurred. After the crater floor, Perseverance began exploring the sedimentary rocks in the Jezero western fan, which is still in progress. On the fan, some float rocks show intense alteration to kaolinite followed by metamorphism [10].

Perseverance instruments which have an original design optimized for lightness, resistance to extreme conditions and performance will be introduced. Doing spectroscopy on Mars is challenging but these instruments have worked perfectly so far. A large amount of data, including some first-time achievements on Mars, have been collected and will be summarized with special emphasis on spectroscopic data.

[1] Farley et al., Science, 2022 ; [2] Bell et al., Science Advances, 2022 ; [3] Wiens et al., Sciences Advances, 2022 ; [4] Liu et al., Science, 2022 ; [5] Scheller et al., Science, 2022 ; [6] Udry et al., JGR Planets, 2023 ; [7] Beyssac et al., JGR Planets, 2023 ; [8] Clavé et al., JGR Planets, 2023 ; [9] Mandon et al., JGR Planets, 2023 ; [10] Royer et al., LPSC 2024.

How to cite: Beyssac, O.: Spectroscopy on Mars with NASA Perseverance rover, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8479, https://doi.org/10.5194/egusphere-egu24-8479, 2024.

Quartz is ubiquitous within continental crust and can virtually be found within all rock types (plutonic, metamorphic and sedimentary). During erosion, weathering and sedimentation processes, it has a very high preservation potential and is often used to trace sediments production and transport dynamics. The QUARTZ project (Multi-methods characterization of quartz for source-to-sink tracing in alluvial sediment and dosimetry approaches – French ANR) aims to use quartz as a tracer for sediment sourcing river dynamics by combining conventional characterization method such as Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), Laser Induced Breakdown Spectroscopy (LIBS), and Cathodo-Luminescence (CL), with dosimetric methods, such as Electronic Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) which are more classically used for Quaternary sediment dating. To this end, one must define a robust quartz chemico-structural and dosimetric signature that can be compared from one sample to the other. We also aim to better understand ESR, OSL, and CL signals controlled by structural quartz defects. These can be either intrinsic (e.g. dislocations, missing/supplementary O or Si), or extrinsic (foreign atoms), each technique being more or less sensitive to these different defects.

In this study, we apply this multi-method approach to the various bedrock lithologies of the Strengbach catchment (ca.40 km²) draining a low mountain range located in the easternmost France (Vosges). These are largely dominated by crystalline metamorphic and plutonic rocks, with secondary Triassic sandstones (Buntsandstein). Bedrock samples have been treated mechanically and chemically to extract quartz grains. These grains have been analyzed using ESR and OSL techniques and mounted on thick sections (100 µm) for CL, LA-ICP-MS, and LIBS analyses. 100-µm thick-sections were used to prevent quartz tearing apart under LA-ICP-MS laser beam. Quartz characterization was completed by the study of whole-rock bedrock thick sections, analyzed with CL, LA-ICP-MS and LIBS approaches.

Preliminary results allow identifying specific quartz chemico-structural signatures not only depending on rock type (gneiss, granite, sandstone) but also on formation process (magmatic, recrystallized, metamorphic or sedimentary). Further comparison between quartz analysis in whole rock and in separated grains samples permit to assess the impact of the chemical treatment on the quartz signatures and to identify quartz populations likely to be more represented in the alluvial sediments produced by the different lithologies. Finally, ongoing analyses point out the complex contribution of trace elements to OSL, ESR and CL signals.

How to cite: Aupart, C., Lerouge, C., Lach, P., Trichard, F., Boulay, M., Rizza, M., Valla, P., Voinchet, P., Rixhon, G., and Tissoux, H.: Quartz chemico-structural characterization: a tool for sediment source tracing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8723, https://doi.org/10.5194/egusphere-egu24-8723, 2024.

In this study, investigated the geology, mineralogy, petrography and geochemistry of metavolcanic rocks in northern Ilgın (Konya). There are two Paleozoic and Mesozoic metamorphic rock groups in the study area. Alluvium and Neogene sediments are unconformably layered over these rocks. Paleozoic metamorphic group include metasediments and metacarbonates. This metamorphic group consist of metaconglomerate at their base and continue upward as metasandstone, metaquartzite, phyllite, schist, metachert, and metacarbonate at the top. Mesozoic metamorphic group consists of metasediments, metacarbonates, and metavolcanic rocks. There is metaconglomerate at the base and continue upward shale, metasandstone, and metacarbonate at the top. The main difference between the two groups is that the Mesozoic metamorphic group contains metavolcanic rocks. These metavolcanic rocks, which are the main subject of this study, occur at five different locations within the study area. These are Dereköy – Kurtlukaya Hill, Küçüktokmak Hill, Kocatokmak Hill, Göleç Hill, and Avdan Village. Metavolcanic rocks are commonly observed as massive metalavas, but in some areas they exhibit a significant degree of foliation. These rocks include quartz, feldspar, and muscovite. In some areas, quartz veins cut the rocks, and in others, iron oxides are observed. The metavolcanic rocks that are the main target of this study are metariolitic - alkaline metariolitic rocks. The rocks have undergone slight metamorphism, and foliation is clearly visible in some samples. The rocks consist of an average of 40-50% matrix and 50-60% quartz, alkali feldspar, muscovite and plagioclase minerals and exhibit a hemicrystalline porphyritic texture. The matrix of the rocks consists of fine-grained quartz, alkali feldspar and sericite minerals. These rocks’ SiO₂ contents vary between 63.60-71.97%; K₂O contents vary between 3.4-10.52%; Al₂O₃ contents vary between 15.78-18.56%; Fe₂O₃ contents vary between 0.94-4.26% and TiO₂ contents vary between 0.02-0.57%. The rocks are calc-alkaline and shoshonitic in character. In addition, the rocks are peraluminous and silica-saturated. Trace element analysis shows that Ba is present in high concentrations (88–391 ppm) in  the rocks. Samples from Avdan and Dereköy have high Zr values (424–597 ppm) and Rb values (190–360 ppm). Eu values ​​(0.06–0.55) are low in all samples. Low Eu and high Ba are state that crustal contamination. The spider diagrams shows a decrease in Sr, Hf, and Ti elements, especially Eu, and an increase in other elements in the rocks. The negative anomalies observed in Sr and Eu elements indicate that fractional crystallization of feldspars. Enrichment of elements such as Th, Nb, and Zr indicate that crustal contamination. These rocks exhibit a relatively LREE-rich, HREE-poor composition, and show fractionation from LREEs to HREEs in normalized distribution pattern according to chondrite. The formation of the rocks includes fractional crystallization, assimilation-fractional crystallization, magma mixing and crustal contamination events. Ilgın metavolcanic rocks were formed as a result of magmatic activity that developed simultaneously with the collision after orogeny in the within plate environment.

Keywords: Geochemistry, Ilgın/Konya, metavolcanic rocks, petrography, Turkey.

How to cite: Sarıkaya, O. and Özdamar, Ş.: Petrography and Geochemistry of the North of Ilgin (Konya) Metavolcanic Rocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9462, https://doi.org/10.5194/egusphere-egu24-9462, 2024.

Photocatalysis is a promising water purification technology, that harnesses the power of light-induced reactions to degrade contaminants. Utilizing visible light in the reactions is imperative, as it comprises a significant portion of the solar spectrum, which aligns with sustainable practices. Graphitic carbon nitride (g-C₃N₄) is a photocatalyst active in visible light, characterized by high chemical and thermal stability, ease of synthesis, and relatively low cost. However, its performance is limited by charge carrier mobility and charge recombination. These limitations might be addressed by synthesizing heterostructures, i.e. composites containing two or more semiconductors. Heterojunctions between g-C₃N₄ and layered double hydroxides (LDH) have shown increased photocatalytic efficiency. LDH are crystalline, hydrotalcite-like materials that enhance the charge separation and light absorption by the heterostructure. These materials can be obtained through various synthesis methods, including coprecipitation and hydrothermal treatment, influencing their properties. Thus, this study aimed to compare heterostructures obtained by different synthesis routes and asses their photocatalytic efficiency.

Three synthesis methods were used to obtain Zn-Cr LDH/g-C₃N₄ heterostructures: coprecipitation, adsorption/coprecipitation, and hydrothermal treatment. For g-C₃N₄ preparation, melamine was heated at 550°C for 5 h. The coprecipitation method involved dissolving zinc and chromium nitrates in DI water, then adding it to a suspension of g-C₃N₄, while simultaneously adding a solution of NaOH and Na₂CO₃. The adsorption/coprecipitation method was based on adding zinc and chromium nitrates to a g-C₃N₄ suspension, then after 30 minutes adding a solution of NaOH and Na₂CO₃. The hydrothermal method included dissolving zinc and chromium nitrates in the g-C₃N₄ suspension, adding NaOH and Na₂CO_3, then placing the suspension in an oven for 24 h at 100°C. The obtained materials were characterized by XRD, SEM/TEM, XPS, TRFL, N₂ adsorption/desorption, and photoelectrochemical measurements. The photocatalytic activity of heterostructures was assessed in batch experiments in aqueous solutions containing 1 ppm of estrone, with a 150 W LED lamp as a source of visible light.

The XRD patterns of obtained materials confirmed the formation of layered phases. The hydrothermal heterostructure was characterized by sharper reflections, which suggested higher structural order and/or larger crystallites. The average specific surface values (S_BET) showed that the hydrothermal composite was characterized by the highest S_BET - 124 m²/g. This indicated its higher porosity, compared to the materials obtained by other methods. The TRFL studies proved that the heterojunctions have lower recombination rates and longer lifetimes of charge carriers. The results of photochemical measurements suggested superior electronic conductivity and charge transfer efficiency for the hydrothermal heterostructure. The determined photoelectrochemical properties agreed well with the photocatalytic activity of heterostructures, which was the highest for the hydrothermal composite. This material led to a 99.5% estrone concentration loss after 60 minutes of reaction, in comparison to 49.9% and 75.8% loss assessed for the materials obtained by coprecipitation and adsorption/coprecipitation, respectively. The results of this study demonstrated the advantage of using the hydrothermal method to obtain LDH/g-C₃N₄ heterostructures with a high efficiency of pollutant photodegradation from aqueous solutions.

This research was funded by the AGH University of Science (Krakow, Poland), grant number 16.16.140.315.

How to cite: Jędras, A., Matusik, J., Dhanaraman, E., Fu, Y.-P., and Cempura, G.: Zn-Cr LDH/g-C3N4 heterostructure for estrone photodegradation: what is the effect of synthesis methods on materials’ properties and degradation efficiency?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9600, https://doi.org/10.5194/egusphere-egu24-9600, 2024.

The widespread occurrence of zearalenone (ZEN) in a variety of grain products and animal feed, coupled with its capacity to accumulate in the food chain, poses a significant health risk for both humans and animals. Its ability to induce estrogen-like effects may disrupt the body's estrogen levels, thereby contributing to reproductive system diseases, even at very low concentrations. The removal of ZEN from aqueous environment is predominantly challenging due to its weakly polar nature, compounded by its high thermal stability. Photodegradation, especially when applying mineral-based photocatalysts, stands out as a promising strategy for environmentally friendly mycotoxin removal. It not only demonstrates cost-effectiveness but also entails the production of negligible secondary pollutants.

Our research employed platy kaolinite (M), synthetic calcined kaolinite nanotubes (MNC), and halloysite purchased from Sigma-Aldrich (HS) as supports for TiO₂, g-C₃N₄, or combination of TiO₂/g-C₃N₄ semiconductors. Each synthesis was designed to consistently yield ~20 wt% of the semiconductor or its mixture in the samples, maintaining a TiO₂ to g-C₃N₄ ratio of 1:1. The sol-gel method was used for TiO₂ synthesis [1], while porous g-C₃N₄ nanosheets were prepared by heating melamine at 550°C, with the addition of ammonium chloride in a 1:1 ratio. The structural, textural, morphological, and light absorption properties of the obtained samples were characterized through XRD, N₂ adsorption/desorption, UV-Vis DRS spectroscopy, Raman spectroscopy, SEM, and TEM..

The UV-induced photodegradation kinetics experiments (365 nm, 10 mW/cm²) were carried out at a consistent initial ZEN concentration of ~10 ppm. ZEN concentrations were determined with high-pressure liquid chromatography (HPLC). The TiO₂-loaded photocatalysts exhibited the slowest photodegradation kinetics, resulting in the final removal of ~41.9% by the M-based sample, ~63.4% by the HS-based sample, and ~86.9% by the MNC-based sample. Conversely, the impregnation with g-C₃N₄ and TiO₂/g-C₃N₄ led to materials exhibiting the fastest kinetics, effectively removing over ~99.9% of the initial ZEN concentration. Notably, the nanotubular-based photocatalysts demonstrated slightly faster kinetics than those observed for the M-based materials and were comparable to those noted for the pure g-C₃N₄. Analogous experiments under visible light irradiation highlighted the synergistic effect for the combination of  both semiconductors, characteristic of Z-scheme heterojunction structures. Among the MNC-based samples, the least efficient photodegradation was demonstrated by the g-C₃N₄-containing sample (~13.7%), slightly higher for the TiO₂-containing sample (~20.3%), and the most efficient removal was observed for the sample containing both semiconductors (~36.6%).

The conducted experiments revealed a significant potential of kaolinite and halloysite nanotubes as carriers for semiconductors in the effective removal of ZEN from aqueous solutions. Future aspects of our research will involve detailed investigations into the degradation pathways of ZEN and the electrochemical characterization of the materials used.

This project was supported by the National Science Centre Poland, under a research project awarded by Decision No. 2021/43/B/ST10/00868.

References:
[1] Dziewiątka K., Matusik J., Trenczek-Zając A., Cempura G. (2023). TiO₂-loaded nanotubular kaolin group minerals: The effect of mineral support on photodegradation of dyes as model pollutants. Applied Clay Science, Elsevier, volume 245, 107123. 

How to cite: Dziewiątka, K., Matusik, J., and Cempura, G.: Efficient photodegradation of zearalenone: Unraveling the potential of photocatalysts based on kaolin group minerals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9623, https://doi.org/10.5194/egusphere-egu24-9623, 2024.

Diffuse Reflectance Infrared Fourier Transform Spectroscopy (FTIR DRIFT) is a widely used method for investigating soil organic materials. The existing literature suggests variations in sample preparation techniques for soil analysis. Notably, the powdering and drying method may influence the presence of organic materials, clay minerals, and carbonates. These minerals are occasionally found as coatings on different mineral surfaces and sometimes as part of the matrix within soil aggregates. This study examined four topsoils of distinct types from Hungary: Arenosol, Leptosol, Gleysol, and Phaeozem (WRB2022). The samples were pulverized both to < 250 µm and < 63 µmAnd also various procedures for drying were used: 1-hour drying sessions at 50 °C, 100 °C, 150 °C, 200 °C, and 250 °C, as well as overnight drying at 50 °C, 100 °C, and 150 °C. Additionally, samples were measured without undergoing extra drying at room temperature. This study aimed to focus on significant organic material bands.

Pulverization has a more pronounced effect on FTIR DRIFT spectra in soils with aggregates, furthermore, when the original soils contain a higher proportion of sand fraction. The drying method affects the measured absorbance values at the highlighted wavenumbers with an underlined influence on the aliphatic components range. Support of the National Research, Development, and Innovation Office (Hungary) under contract K142865, and Eötvös Loránd Research Network SA41/2021 are gratefully acknowledged.

How to cite: Szalai, Z., Karlik, M., Jakab, G., Vancsik, A., Hatvani, I. G., Cseresznyés, D., and Király, C.: Effect of sample preparation on the FTIR DRIFT spectra in the case of soils with different organic material content, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10421, https://doi.org/10.5194/egusphere-egu24-10421, 2024.

Similar to Ca-apatites, carbonate substitutions are also possible in Pb-apatites although they are still not fully characterized [1,2]. Therefore, for the first time, a comprehensive comparison of the IR spectra of synthetic Pb-apatite analogs has been carried out with a detailed examination of the rather often ignored carbonate substitutions. CO₃^2- ions can be substituted in the apatite structure in two different positions: by substitution of an anion located in the X-position in the channel, such as OH- or halogen (A-type substitution), or by substitution of an anion in the tetrahedral position, such as PO₄^3- or AsO₄^3- (B-type carbonate substitution). This can be illustrated by the following chemical formula: Pb_10-y(Na,K)_y[(PO₄)_6-y(CO₃)_y][(X)_2-2x(CO₃)_x], where x≈y. IR studies have shown that in apatites prepared at high temperature, most of the carbonates are located in the channel. Under low-temperature environmental conditions, the formation of AB-carbonated Pb apatites is much more plausible [3]. Some Pb apatites, such as fluoride apatites e.g. Pb₁₀(AsO₄)₆F₂, do not tend to incorporate carbonate at all, at least not during precipitation from solutions with CO₃^2- concentrations similar to environmental (pCO₂=10^-3.5 atm). This is likely due to the greater ordering in apatite channels, where the fluoride anion occupies the mirror plane.

In the present work, various Pb-apatites containing As and V were prepared by precipitation from an aqueous solution in the presence of Na⁺ cations at room temperature and open to the air. The type of A- or B- carbonate substitution was determined in IR spectra collected at room temperature based on asymmetric stretching of the carbonate (ν₃) and out-of-plane bending (ν₂) modes. The high-frequency component of the ν₃ region of the A-type carbonate for Pb apatites showed the greatest variability with chemical composition. For example, in Pb₁₀(AsO₄)₆OH_0.86(CO₃)_0.07 hydroxylmimetite, the bands at 1462 and 1421 cm^-1 are attributed to A-type carbonate substitution, while the bands occurring at 1385 and 1348 cm^-1 are associated with B-type. Compared to lead phosphates and vanadates, carbonate bending oscillations ν₂ at 870 cm^-1 are not apparent in arsenate Pb apatites due to overlap with the As-O stretching mode. In situ IR measurements were also carried out during temperature rise to 500 °C to determine the thermal stability of individual carbonate substitutions in the Pb-apatite structure. In general, most Pb-apatites begin to release carbonates around 300 °C. As the temperature increases, bands in the ν₂ and ν₃ carbonate regions begin to disappear until the apatite structure completely disintegrates.

References

[1] Yoder, C. H., Bollmeyer, M. M., Stepien, K. R., & Dudrick, R. N. (2019). The effect of incorporated carbonate and sodium on the IR spectra of A-and AB-type carbonated apatites. American Mineralogist: Journal of Earth and Planetary Materials, 104(6), 869-877.

[2] Kwaśniak-Kominek, M., Manecki, M., Matusik, J., & Lempart, M. (2017). Carbonate substitution in lead hydroxyapatite Pb₅(PO₄)₃OH. Journal of Molecular Structure, 1147, 594-602.

[3] Lempart, M., Manecki, M., Kwaśniak-Kominek, M., Matusik, J., & Bajda, T. (2019). Accommodation of the carbonate ion in lead hydroxyl arsenate (hydroxylmimetite) Pb₅(AsO₄)₃OH. Polyhedron, 161, 330-337.

How to cite: Puzio, B. and Manecki, M.: Carbonates substitution in lead apatites – IR spectroscopic study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11495, https://doi.org/10.5194/egusphere-egu24-11495, 2024.

Jarosite, a hydrous K-rich sulfate mineral, was found in fine-grain quantities on the Martian surface by the Opportunity rover in 2004. Jarosite found in some terrestrial settings can form a complete solid solution with ammoniojarosite through substitution of the ammonium ion (NH₄⁺) which replaces K⁺ within its crystal structure. Requiring water and acidic conditions to form, jarosite stands as a potential indicator of ancient N-bearing environments on the Martian surface. The Mars Perseverance rover is currently exploring the Martian surface with analytical instrumentation that may be capable of detecting N-rich jarosite, including the SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) and the PIXL (Planetary Instrument for X-ray Lithochemistry) detectors. To investigate the detection of N in jarosite with Raman and X-ray spectroscopy, we analyzed several terrestrial samples of jarosite and ammoniojarosite using laser Raman spectroscopy and electron-excited Wavelength Dispersive X-ray Spectroscopy (WDS). Comparison of high wavenumber regions of Raman spectra with WDS spectra of N K-α X-rays on the same samples will be used to investigate detection and quantification of N as ammonium in jarosite.

How to cite: Bushmaker, S., Nachlas, W., and Bonamici, C.: X-ray and Raman spectroscopy of jarosite and ammoniojarosite from several terrestrial localities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12017, https://doi.org/10.5194/egusphere-egu24-12017, 2024.

Apatite is a ubiquitous mineral in plutonic carbonatites (magmatic carbonate-rich rocks) and associated rock types (Chakhmouradian et al., 2017). Carbonatites are enriched in incompatible elements such as P and rare earth elements (REE), which are accommodated into apatite structure among many other elements (e.g., Hughes and Rakovan, 2015), making apatite a suitable tracer for changes in magmatic-hydrothermal geochemistry.

Sokli carbonatite complex, located in eastern Lapland, Finland, is the westernmost intrusion of the Kola Alkaline Province (Vartiainen, 1980 and references therein). The Sokli complex encompasses multiple generations of carbonatite magmatism, which compositionally span from calcite carbonatite to dolomite carbonatite to late-stage Ba, Sr, REE-enriched dolomite-rich veins. Carbonatites are associated with several generations of phoscorites, exotic magnetite-apatite cumulates typically found in carbonatite complexes. Apatite is present in most rock types in the complex, from an accessory to a rock-forming mineral.

The Sokli complex has been studied for decades (O’Brien and Hyvönen, 2015), but the composition and role of magmatic apatite has not been discussed in detail outside of phosphorous mineralization studies. Previous studies indicate that with progressive fractionation the concentrations of Ba, Sr, REE, and F increase in whole-rock and mineral compositions (O’Brien and Hyvönen, 2015 and references therein). Questions that still remain open include whether apatite has recorded the proposed different magmatic and metasomatic stages and if apatite chemistry could provide arguments for the proposed liquid immiscibility relationship between carbonatites and phoscorites (Lee et al., 2004).

A variety of apatite-bearing rock types from the Sokli complex were sampled. The composition of apatite will be studied in situ for major and trace elements with electron microprobe analyzer (EPMA) and laser ablation inductively coupled mass spectrometry (LA-ICP-MS), respectively.

References cited:

Chakhmouradian, A.R., Reguir, E.P., Zaitsev, A.N., Couëslan, C., Xu, C., Kynický, J., Mumin, A.H., Yang, P., 2017. Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance. Lithos 274–275, 188–213.

Hughes, J. M., Rakovan, J. F. 2015. Structurally robust, chemically diverse: apatite and apatite supergroup minerals. Elements 11, 165–170.

Vartiainen, H., 1980. The petrography, mineralogy and petrochemistry of the Sokli carbonatite massif northern Finland. Geological Survey of Finland, Bulletin 313.

O’Brien, H., E. Hyvönen. 2015. The Sokli carbonatite complex in Maier, W.D., Lahtinen, R., O’Brien, Hugh (Eds.), Mineral Deposits of Finland. Elsevier. 305–325.

Lee, M.J., Garcia, D., Moutte, J., et al., 2004. Carbonatites and phoscorites from the Sokli complex, Finland. In: Wall, F., Zaitsev, A.N. (Eds.), Phoscorites and Carbonatites from Mantle to Mine: The Key Example of the Kola Alkaline Province. The Mineralogical Society of Britain and Ireland, London, 133–162.

How to cite: Karvinen, S., Beier, C., and Heinonen, A.: Apatite in the Sokli carbonatite complex, Finland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12115, https://doi.org/10.5194/egusphere-egu24-12115, 2024.

Exploring the Raman oxygen isotope signatures of calcite and vaterite

Oxygen isotope tracers have been increasingly used to differentiate between solid-state and fluid-mediated mineral transformation pathways (e.g., Julia et al. 2023). When ¹⁸O enrichment within oxyanion bearing minerals is analysed using Raman spectroscopy, the kinetically hindered formation of different isotopologues can also provide an in-situ timer for these processes (King et al. 2014). However, at present we assume that each isotopologue band in the vibrational spectrum has an equivalent intensity when present at the same concentration within the crystal structure. Here we test this hypothesis by exploring the vibrational spectra of two important oxyanion-bearing minerals, calcite and vaterite. These are polymorphs of CaCO₃ and reflect a metastable, transition phase and the thermodynamically most stable mineral expected in many natural systems found at the Earth’s surface.

Here we have used a joint experimental and theoretical approach to demonstrate that isotopic substitution changes both band positions and band intensities to different extents, depending on the vibrational spectroscopy method used and the bands examined. Density functional theory simulations (King et al. 2022) show that for calcite, the most intense Raman bands, the υ₁ symmetrical stretching, related to individual isotopologues are found to have very similar intensities and are not affected by changes in isotopologue distribution within the material. Splitting of some bands due to changes in symmetry correlate to observed effects in experimentally produced ¹⁸O enriched calcite.In contrast, vaterite vibrational bands were found to change more extensively upon isotope substitution, thus they can only be used to evaluate relative changes in the ¹⁸O concentration within the material. These results are expected to contribute to a deeper und less ambiguous understanding of evaluating isotopic enrichment effects in the vibrational spectra of calcium carbonates.

Julia et al. 2023 Chemical Geology, 621, 121364.

King et al. 2014 Crystal Growth & Design, 14, pp. 3910.

King et al. 2022 Crystals, 13, 48.

How to cite: King, H. E. and Živković, A.: Exploring the Raman oxygen isotope signatures of calcite and vaterite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12281, https://doi.org/10.5194/egusphere-egu24-12281, 2024.

The understanding of the vitrification processes encompasses all the fields between geo- and material- sciences. Glass represents a non-equilibrium picture of its parental super-cooled liquid (SCL) and the last melt fraction quenched after a volcanic eruption. The SCL is usually read as a system that moves away from equilibrium without having enough time to explore the phase-space. In these conditions it is unable to find new configurations, causing a drop of the thermodynamic equilibrium and a glass is formed. This system is named non-ergodic and at eruptive temperatures represent a key component that may experiences fragmentation [1]. This particular state is generally referred to the thermal interval preceding the glass transition temperature (T_g, T at which the viscosity is 10¹² Pa s) and the monitoring of its micro-structural evolution requires the less invasive experimental technique. With this regard we have used the deep UV-Raman spectroscopy to investigate a set of silicate model-glasses, loaded with different iron contents. This spectroscopic approach allows for the acquisition of fluorescence-free spectra with a maximized signal in the high-wavenumber region (between 850-1300 cm^-1) thus providing the finest conditions for the assessment of the tetrahedral arrangement through the Qⁿ deconvolution analysis (n represents the number of bridging oxygens) [2]. Here we correlate the trend of each Qⁿ unit with temperature across the T_g-interval. Our results display a clear T-dependent rearrangement of the Qⁿ distribution in function of iron content. Our finding, supported by differential scanning calorimetry, thermal dilatometry, Mössbauer, FTIR and ATR measurements, may deliver helpful insights into the thermal-dependent microstructural evolution through the T_g-interval and the viscous behavior of silicate SCLs.

• _{[1] D. B. Dingwell, Science 273, 1054 (1996).}
• _{[2] M. Cassetta, B. Rossi, S. Mazzocato, F. Vetere, G. Iezzi, A. Pisello, M. Zanatta, N. Daldosso, M. Giarola, and G. Mariotto, Chem. Geol. 644, 121867 (2024).}

How to cite: Cassetta, M., D'Amico, F., Rossi, B., De Bona, E., Sambugaro, A., Biesuz, M., Almeev, R., Vetere, F., Giordano, D., Enrichi, F., Daldosso, N., and Mariotto, G.: In-situ structural analysis of silicate supercooled liquids through deep-UV Raman spectroscopy , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12774, https://doi.org/10.5194/egusphere-egu24-12774, 2024.

Determining the habitability of planets remains a fundamental question in science and society. In this study, we harness network theory to explore the unique patterns exhibited by minerals and their mineralizing environments in both biotic and abiotic contexts throughout the evolution of Earth and other terrestrial bodies in our solar system [1-. By examining mineralogical networks across diverse planetary systems, including early solar system bodies, the early Hadean Earth (closely related to modern-day Mars), plate tectonics, and modern Earth, we gain valuable insights into Earth's history and the factors that have shaped the development and sustainability of life. Our investigation reveals distinct characteristics within biotic networks, setting them apart from their abiotic counterparts.

This research significantly advances our understanding of the intricate interplay between Earth and life. Network analysis offers deeper insights into the connections between minerals and living systems, providing invaluable perspectives on the emergence and co-evolution of life on our planet. Moreover, our findings contribute to identifying and characterizing planetary biosignatures, essential for the search for extraterrestrial life. Recognizing these unique patterns within biotic networks lays the groundwork for developing targeted exploration strategies for detecting potential biosignatures and interpreting the complexities of planetary environments.

Our innovative network analysis of minerals and mineralizing environments sheds new light on the relationships between Earth and life. By delving into the intricate connections within biotic and abiotic systems, we deepen our understanding of Earth's dynamic history and enhance our knowledge of potential habitats for life beyond our planet.

How to cite: Morrison, S., Prabhu, A., Hazen, R., Wong, M., Giovannelli, D., and Eleish, A.: Characterizing life influence on Earth's mineralogy via mineral network analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14196, https://doi.org/10.5194/egusphere-egu24-14196, 2024.

There is a constant search for materials that could be used as geochemical barriers and fillers for radioactive waste storage containers. One of effective methods of immobilizing toxic elements is their precipitation in the form of sparingly soluble crystalline phases. The purpose of this study was to test the effectiveness of co-precipitation of Th from aqueous solutions in the form of crystalline lead phosphates. Such phases have high stability and low solubility and the presence of Pb has an additional effect on reducing the radiation.

Three sets of experiments were carried out by adding reagents into a solution containing non-radioactive Th at a concentration of 400 ppm:

(A) a solution containing PO₄^3- ions (at a concentration of 1 g/L);

(B) a solution containing Pb²⁺ and a solution containing PO₄^3- ions (at concentrations of 3.5 g/L and 1 g/L, respectively) added dropwise simultaneously;

(C) solutions containing Pb²⁺, PO₄^3-, and Cl^- ions (at concentrations of 3.5 g/L, 1.0 g/L, and 0.12 g/L, respectively) added dropwise simultaneously.

All experiments were repeated at pH = 3, 5 and 7. No reaction occurred in experiment (A), while in experiments (B) and (C) the solid phases crystallized, and the Th concentration dropped from 400 to about 0.05 ppm. In the absence of Cl (experiment B), the reaction at pH=3 led to the formation of "phosphoschultenite" PbHPO₄ while at pH = 5 and 7 Th-bearing hydroxylpyromorphite Pb₅(PO₄)₃OH was formed. In the presence of Cl ions (experiments C), Th-bearing pyromorphite Pb₅(PO₄)₃Cl was formed over the entire pH range. Th was removed from solution by coprecipitation with Pb and incorporation of Th into lead phosphate structure.

The results showed that Pb must be present for Th to be effectively immobilized from solution in the form of phosphate phases. The presence of Cl is not as important as the presence of Pb in terms of removal efficiency, but it may be crucial for the long-term stability of the precipitated phases, since Pb₅(PO₄)₃Cl has higher stability and lower solubility than Pb₅(PO₄)₃OH. These findings pave the way for development of potential innovative techniques for immobilizing Th from waste and contaminated solutions, which could have implications for the safety and long-term viability of various nuclear waste disposal programs. This research was funded by National Science Center research grant no. 2021/43/O/ST10/01282.

How to cite: Manecki, M., Wrona, P., Brzoska, A., and Staszel, K.: Immobilization of radioactive Th by coprecipitation with lead apatites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14330, https://doi.org/10.5194/egusphere-egu24-14330, 2024.

Arsenic is a world-wide serious health problem occurring in various types of rocks, soil, and contaminated water resources. However, it is not always an acute health problem, as concentrations are often comparably low. But recently, it gained increasing attention with the introduction of new laws in Germany (and the EU) regarding the deposition of excavated sediments, e.g., in the context of the construction of tunnels or the mining of gravel and sand etc. The decision on whether excavated material can be used as backfill or needs landfilling depends on the analysis and classification relative to specified limit values. In the latter scenario, this can result in a significant increase in costs. It is mandatory to determine the heavy metals and arsenic (among other parameters) in the solid sample and to produce and analyze an eluate of the sample to identify soluble harmful elements that could potentially contaminate the groundwater.

At a first glance, arsenic contents in solid and in eluate often show erratic patterns, which could not be explained. In clastic sediments, an often observed (weak) correlation between arsenic and iron in solid analyses led to the assumption that arsenic is bound in iron-hydroxides. However, a comprehensive examination of the chemistry and mineralogy of a large number of samples did not reveal any clear correlations. Therefore, we studied drill-core samples and sediment profiles of poorly consolidated Miocene clastic sediments, including gravel, sands, clay and silt from different areas of the Northern Alpine foreland basin (mostly from the Munich and Ingolstadt areas).

Based on geochemical analyses, we found different “arsenic-types”: Some samples show the expected correlation pattern for arsenic in the solid and the eluate. Some samples, however, show high arsenic in the solid and low arsenic concentrations in the eluate. Also, remarkably, samples with rather low arsenic contents in the solid and high arsenic in the eluate were observed. No systematic correlation with other chemical elements or with macroscopic characteristics, e.g. grain size, could be identified. Our detailed mineralogical investigation of more than 30 samples showed that XRD analysis, which is usually used to identify the mineralogy in the finest fraction, is not sufficient to explain this behavior. Therefore, we separated all mineral phases (also in the clay fraction) and analyzed their mineral chemistry (in particular their arsenic content) with SEM, their texture with high-resolution Keyence microscopy (2000x), and combined the results with extensive leaching experiments.

Our results imply that mineralogy is the key to understanding the elution behavior of arsenic. Regarding the binding characteristics of arsenic, three different mineral types can be distinguished: 1) Fe-, Si- and Al-Hydroxides (minor tourmaline, apatite and zircon) can bind arsenic relatively well (no arsenic in the eluate), 2) chlorite and mica can adsorb high amounts of arsenate but with a weak bond (high As in eluate) and 3) smectite which releases its arsenate step-by-step with the increasing degree of swelling. The study showed that only with a detailed mineralogical and mineral-chemical analysis profound predictions on the elution behavior of arsenic can be made.

How to cite: Aßbichler, D., Weichselgartner, N., Diesner, N., Kayalar, M., Otte, C., Heuss-Aßbichler, S., Tautenhahn, S., and Friedrich, A. M.: Mineralogy – the key to understanding and predicting the elution behavior of arsenic , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14683, https://doi.org/10.5194/egusphere-egu24-14683, 2024.

Gemological reports have gained a crucial role in today’s gemstone trading because they provide buyers and sellers with information regarding gem features, which in turn can be translated to monetary value. Although there is information about technics to separate Colombian emeralds from other countries, not much information is available about how to differentiate emeralds from the Western Belt (COC), and those from the Eastern Belt (COR), two main produced zones in Colombia, those districts more recognized are, Muzo and Chivor, respectively. This work aims to show the advances made in one of the techniques used in a gemological laboratory to determine the origin of emeralds.
The analysis of fluid inclusions via Raman spectroscopy can yield beneficial information regarding the chemical properties of mineral systems. Primary fluid inclusions trapped by emerald permit us to know the chemistry and the thermobarometric conditions of the mineralizing fluids. Fluid inclusions are usually three-phase inclusions with contain three or more phases including liquids, gases, and salt (halite). Sometimes they are multiphase with solids such as calcite. The gas phases are typically CO2, N2, and CH4 (Cheilletz et al., 1994; Giuliani et al., 1993; Giuliani et al., 1995; Romero & Hernandez, 1999; García-Toloza et al., 2017). Raman spectra of CO2 exhibit two bands near 1285 cm-1 and 1385 cm-1, this feature is well-known as the Fermi doublet (Fernandez, 1983; Howard-Locke, 1971); the distance between these bands is proportional to the fluid density (Rosso & Bodnar, 1995; Song Y. et al., 2003). 
The data of ∆ Fermi doublet suggest that values below 103.1 are exclusive from the COR, whereas there is an overlap from 103.1 to 103.4. Additionally, the position of the two main CO2 bands varies significantly between the two Colombian belts. The location of peaks from the COR are found at lower energy levels. Thus, this method may be used to estimate the provenance of some populations, the Fermi doublet is not only helpful to differentiate between the Colombian emerald belts but also between Colombian emeralds from samples from Brazil and Afghanistan.

How to cite: Garcia-Toloza, J., Betancur, C., Alvarado, H., and Cedeño, C. J.: Raman spectroscopy analysis of fluid inclusions as a tool in determination of origin of Colombian emeralds., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14692, https://doi.org/10.5194/egusphere-egu24-14692, 2024.

The Styrian Basin, situated in the transition zone between the Pannonian Basin and the Eastern Alps, is believed to have formed above a lithospheric wedge, which have been affected by a subduction. The Late Miocene-Pliocene alkali basalts sampled the subcontinental lithospheric mantle beneath the area, bringing mantle xenoliths to the surface (e.g., [1] [2]). These xenoliths are amphibole-rich, indicating extensive modal metasomatism at mantle depth. Our goal is to better understand the possible fluid and melt-related processes in these xenoliths by studying fluid and melt inclusions in them. In the studied samples, one category of xenoliths contains both fluid and melt inclusions (co-entrapped), while the other contains only fluid inclusions. We carried out 3D confocal Raman mapping, Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM), Electron Microprobe Analysis (EMPA), and Scanning Electron Microscope with Energy Dispersive Spectroscopy (SEM-EDS). Our primary objectives are to 1) gain insights into the nature of metasomatic agents based on fluid and melt inclusions and 2) test the applicability of 3D Raman mapping on inclusions. The studied inclusions are primary (fluid inclusions) and pseudosecondary (fluid and melt inclusions), occurring in orthopyroxene, clinopyroxene, and amphibole. The fluid inclusions are irregular to negative crystal-shaped (3-100 μm), whereas melt inclusions are glass-rich with rounded to negative crystal shapes (4-15 μm).

A series of 3D Raman mapping on these fluid inclusions has revealed complex phase assemblages comprising fluid and solid phases (magnesite, silicate glass, pyrite, talc, anhydrite, and nahcolite). The fluid is dominated by CO₂ (up to 99.3 mol%) and H₂O (up to 8.7 mol%). EMPA indicates that the trapped silicate glass in the melt inclusions is H₂O-bearing (up to 3.3 wt%) and exhibits an evolved composition (i.e., trachyandesitic composition with SiO₂ between 54.31-60.65 wt%) relative to the host basalt of the studied xenoliths.

We discovered pargasitic amphiboles within SiO₂-rich glass in the melt inclusion that co-entrapped with the CO₂-H₂O-rich fluid phase (where H₂O content is likely high relative to mantle fluids). This strongly suggests that amphiboles were likely crystallized from an immiscible SiO₂-rich melt and CO₂-H₂O-rich fluid that could have been circulating in the mantle wedge above a subducted slab. This immiscible component is suggested to be a metasomatic agent that modified this mantle portion beneath the Styrian Basin.  Furthermore, this study revealed that the laser-induced heating effect could overestimate sulfides in the 3D Raman models, while silicate glass could be underrepresented due to its low Raman scattering properties. However, complementary FIB-SEM serial slicing provides a clear outline of silicate glass in fluid inclusions. Despite these limitations, 3D Raman mapping has proven to be a powerful tool for unravelling complex phase assemblages in inclusions.

This research was supported by the NKFIH_FK research fund nr. 132418 to M. Berkesi. Part of this research was funded by the Doctoral School of Earth Sciences of the University of Pécs.

References:

[1]. Aradi et al., 2019; Földtani Közlöny, 149 (1). pp. 35-49.

[2]. Aradi et al., 2017; Tectonics, 36, 2987–3011.

Keywords: 3D Raman mapping, complex inclusions, mantle metasomatism, subduction zone, Styrian Basin.

How to cite: Myovela, J. L., Aradi, L. E., Spránitz, T., Hegedűs, M., Konečný, P., Kovács, J., and Berkesi, M.: Unravelling metasomatic agent in amphibole-rich upper mantle xenoliths from the Styrian Basin (W-Carpathian Pannonian Region): Insights from 3D Raman mapping of complex inclusions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16706, https://doi.org/10.5194/egusphere-egu24-16706, 2024.

Earthquakes result from the brittle failure of rocks at depths and are primarily induced by far-field tectonic stresses. Despite this general understanding, the atomic-scale mechanisms triggering brittle failure in dry ductile crustal rocks remain elusive. Quartz, a widespread mineral in the lower crust, undergoes an instantaneous polymorphic transformation from the α to β phase under pressure and temperature conditions aligning with estimates for several lower-crustal paleo-earthquakes, recorded as pseudotachylytes. The α–β quartz transition is characterized by displacive reversibility. As α–quartz approaches the transition temperature (T_c = 847 K for a free quartz crystal at atmospheric pressure) under constant pressure, its volume increases nonlinearly without abrupt jumps. However, near the phase-transition temperature, the bulk modulus of quartz exhibits a notable drop from approximately 30 GPa to nearly zero, followed by an abrupt rise to over 70 GPa within 10 K temperature range (Lakshtanov et al., 2007).

Near the α–β transition, quartz inclusions within garnet hosts should develop substantial differential strain, thereby imposing strong differential stresses on the surrounding host crystal. We used in situ high-temperature Raman spectroscopy on quartz inclusions in garnet to monitor the structural deformation and atomic dynamics across the phase transition. The temperature-dependent behaviour of the phonon wavenumbers (ω) in quartz inclusions, particularly the hardening and disappearance of a minimum in ω(T) for A modes near 208 and 464 cm^-1 (related to the α–β phase transition), along with the persistence of Raman activity at ~128 cm^-1 and ~355 cm^-1 above T_c, confirms the accumulation of abnormally high strain in confined quartz grains near the anticipated phase transition. The stored elastic energy in the inclusion is subsequently released through the inclusion-host boundary into the host during the α–β transition. This release causes the garnet around the quartz inclusion to fracture or, in some instances, shatter due to the significant differential stresses forming within the inclusion at its transition. Notably, inclusions of apatite and zircon within the same garnets remain unchanged under the same conditions, thereby excluding the possibility of fracturing being caused by the host garnet itself.

Our experiments show that the α–β transition of a single quartz inclusion in garnet is sufficient to fracture the host phase in a laboratory environment. This process can be upscaled to quartz-bearing rocks at lower crustal conditions and might provide the initial mechanical instabilities necessary to trigger ductile and/or brittle deformation in quartz-bearing rocks, eventually leading to earthquakes.

References

Lakshtanov, D.L., Sinogeikin, S.V., Bass, J.D., 2007. High-temperature phase transitions and elasticity of silica polymorphs. Physics and Chemistry of Minerals 34, 11-22.

How to cite: Gilio, M., Morana, M., Angel, R. J., Mihailova, B., and Alvaro, M.: High-temperature Raman spectroscopy of quartz inclusions in garnet: a tool to investigate lower crustal rheology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16793, https://doi.org/10.5194/egusphere-egu24-16793, 2024.

Sulfuric acid speleogenesis (SAS) is a general cave formation process in carbonate rocks in the presence of sulfuric acid. Such caves are mainly formed at and above the water table by abiotic or/and biotic oxidation of hydrogen sulfide (H₂S). One possible source of H₂S may be volcanic activity. The oxidation of H₂S produces sulfuric acid that immediately reacts with carbonate host rock, producing replacement gypsum and CO₂.

The Western Cordillera in the Peruvian Andes, characterized by volcanic and tectonic activity, features substantial travertine deposits. Among the most interesting and, at the same time, less known are the Mulapampa travertines located in the vicinity of the active Ampato-Sabancaya Volcanic Complex (ASVC). There are numerous collapse sinkholes in the travertine cover, and within three of them, caves have been found. discovered in three of them. Particularly interesting is the Gruta con lago cave, the bottom of which is located at the level of the current water table (ca. 40 m below ground level). It does not have the characteristic morphology of active SAS caves, but several speleogenetic by-products – mainly thick gypsum deposits – are typical of such features.

Mineralogical studies of sediment samples from the lake at the bottom of Gruta con lago corroborated the sulfuric acid genesis of the cave. Native sulfur was detected in those samples, among others. Microscopic examination of native sulfur crystals reveals traces of substantial corrosion attributable to the activity of sulfur bacteria. In the same cave lake's bottom sediments, framboidal pyrites formed inside the biofilms (presumably of sulfate-reducing bacteria) were found. Common secondary minerals in SAS caves, such as barite or celestine, are present on the cave bottom and walls.

This research was funded by the National Science Centre (Poland), grant No 2020/39/B/ST10/00042, and the Institute of Earth Sciences, University of Silesia, Poland.

How to cite: Tyc, A., Ciesielczuk, J., Gaidzik, K., and Powolny, T.: Sulfuric acid speleogenetic by-products and secondary minerals in caves of the Mulapampa travertines (Western Cordillera, Andes, Peru), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17099, https://doi.org/10.5194/egusphere-egu24-17099, 2024.

The Dellen impact structure is located in a ca. 20 km wide basin filled by two lakes in the east central Sweden. The complex structure is covered by a thick moraine deposit, and most impact melted material can be found as loose blocks and boulders scattered throughout the moraine. Geophysical measurements show the presence of a coherent impact melt body about 9 km wide and 200-500 m thick for which impact ages  between 90, 110, to 140 Ma were determined [1]-[2]. 

The impact melt glass (commonly referred as dellenite) consisting of phenocrysts of subhedral orthopyroxene (Wo₄En₆₃Fs₃₃), skeletal plagioclase (average An₅₉Ab₃₈Or₃), and euhedral magnetite within a glassy matrix of rhyolitic composition. MicroFTIR measurements performed in the glass matrix and euhedral glass blebs within the skeletal plagioclase show the presence of 1.4 wt% water in the rhyolitic glass. We estimated that the dellenite vitrified at ca. P=200-300 bar by comparing the glass water content  with the water solubility of a similar composition silicate melt following  Papale's model [3].

Dellenite orthopyroxene was studied by polarized FTIR spectroscopy, Mössbauer spectroscopy, single crystal X-ray diffraction and EMPA. They are iron rich enstatite (Wo₄ En₆₃ Fs₃₃) with a Fe³⁺/Fe_tot ratio of 1.6%. They have very weak to absent OH vibrational bands in the IR spectra, corresponding to H₂O contents ranging from 0 to 39 ppm H₂O, a variability suggesting H loss during post-formation processes, which may occur via the relatively fast redox reaction Fe²⁺ +OH^- =Fe³⁺ +O^2- +½H₂. 

In volcanic pyroxenes H loss may be a common process occurring at different moments from crystallization to post-eruption. However, H incorporation in pyroxene is associated with point defects governed by slow kinetics diffusion rates, which are retained in the structure when H is lost. By reversing the redox reaction the original H content of pyroxene can thus be recovered by thermal annealing experiments under reducing conditions [4]-[5].

In order to restore H that was possibly lost, dellenite pyroxenes were thermally annealed under hydrogen atmosphere (at 1 Atm) in a horizontal glass-tube furnace by thermal annealing experiments at 700°C for 17 hours. FTIR spectra were recorded after each heating step. All the samples increased their hydrogen content and the final average water content is 77 ppm. 

Cation partition as derived by the SC-XRD and EMPA were used to calculate the orthopyroxene closure temperature (Tc) which is expression of the cooling rate for the cpx-host rock. Preliminary results point to a high Tc (833°C) due to a quite fast host-rock cooling rate. 

A tentative model for the evolution of the rhyolitic portion of the Dellen impact melt is under development merging geophysical data with our experimental data on water content of pyroxene and glass, and pyroxene geospeedometry.  

References:

[1]Henkel H (1992) Tectonophysics 216, 31-40

[2]Mark DF Lindgren P Fallick AE (2014) Geological Society of London Special Publication 378, 349-366

[3]Papale P (1999) Am Mineral 84, 477-792

[4]Weis FA Skogby H Stalder R (2016)  Am Mineral 101(10): 2233-2247

[5]Nazzareni S Barbarossa V Skogby H Zanon V Petrelli M (2020)  CMP 175:87

How to cite: Nazzareni, S., Giuli, G., and Skogby, H.: Dellen crater impact melt rock: pyroxenes as a proxy for melt thermal history and water content, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17632, https://doi.org/10.5194/egusphere-egu24-17632, 2024.

The mantle transition zone (MTZ) is known to be potentially hydrated as laboratory
experiments have shown that the two major mineral phases namely wadsleyite (β-M₂SiO₄ ;
M: Mg, Fe) and ringwoodite (γ-M₂SiO₄; M: Mg, Fe) can accommodate significant amounts of
water in the form of hydroxyl ions in their crystal structure. Direct in-situ evidence of the
MTZ being (at least locally) hydrated has been derived from natural diamonds containing
hydrous ringwoodite inclusions (Pearson 2014, Nature). Hence, in this study, we have
investigated the crystal structure and the thermoelastic properties of Fe-bearing ringwoodite
as a function of temperature, pressure, and water content (0 wt%, 1.56 wt%, 3.3 wt%) using a
combination of first-principles density functional theory (DFT) and quasi-harmonic
approximation (QHA). Our calculation reveals that hydration in general causes a reduction in
the sound wave velocity of ringwoodite. However, the ‘reduction’ brought in by hydration is
significantly suppressed at pressures corresponding to the lower part of the MTZ.
Consequently, the sound wave velocities for the 1.56 wt% water-containing ringwoodite
model is found to become very similar to the sound wave velocities of the anhydrous
ringwoodite. However, when the water concentration is increased further to ~3.3 wt%, the pressure-induced
suppression at lower MTZ pressures though present is not significant. These findings indicate that though seismic
waves may not be able to precisely decipher the state of hydration of the lower part of MTZ
when the water concentration is less than 1.56 wt%, it is still robust enough to locate regions
of very high water concentration ~ 3.3 wt%.

How to cite: Mondal, R., Shukla, G., and Chatterjee, S.: Are seismic waves robust enough to detect the presence of water in the lower part of the mantle transition zone?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17688, https://doi.org/10.5194/egusphere-egu24-17688, 2024.

At high temperatures, alkali feldspar consists of a continuous solid-solution between the Na (albite) and K (K-feldspar) end members. Below about 600°C, a miscibility gap opens, the limits of which are determined by the so-called solvus. Alkali feldspar of intermediate composition tends to exsolve when cooled from temperatures of magmatic or metamorphic crystallization, forming an intergrowth of Na- and K-rich lamellae, a microstructure referred to as perthite. Initially, coherency is maintained across the lamellar interfaces and it may be preserved over geological times. Since the lattice parameters of alkali feldspars strongly depend on composition, the exsolution lamellae must be strained to maintain coherency at the interfaces. The elastic energy required to strain the lamellae counteracts exsolution and equilibrium compositions of coexisting coherent exsolution lamellae define a coherent solvus which lies below the solvus for strain-free phase equilibria. Segregation of Na and K and subsequent lamellar coarsening is achieved by thermally activated Na-K interdiffusion. Therefore, compositions and widths of the exsolution lamellae could be used to reconstruct cooling histories. Knowing the shape and position of the coherent solvus is key for the corresponding geo-speedometry applications.

To determine the coherent solvus, initially homogeneous disordered, gem-quality alkali feldspar was annealed at temperatures between 440°C and 560°C and at atmospheric pressure, which caused it to exsolve into coherently intergrown 10 to 20 nm wide lamellae, the compositions of which were directly determined with atom probe tomography.

The application of different annealing times showed that thermodynamic equilibrium was reached during the experiments. The obtained lamellar composition define points on the coherent solvus, which were for the first time measured directly for alkali feldspars.

Additionally, equilibrium Na-K partitioning experiments between NaCl-KCl melt and the same alkali feldspars as used for the exsolution experiments were performed at atmospheric pressure and at temperatures between 800°C and 1000°C to calibrate a thermodynamic mixing model supplemented by a model for the elastic energy required for coherent exsolution. The coherent solvus calculated from the thermodynamic model and the directly measured coherent solvus are in excellent agreement. This indicates that the developed models provide an adequate description of phase equilibria in coherent lamellar intergrowth. The directly measured coherent solvus and the models form a solid base for potential applications of geo-speedometry in coherently exsolved alkali feldspars.

How to cite: Heuser, D., Dubosq, R., Bian, G., Petrishcheva, E., Habler, G., Gault, B., Lengauer, C. L., Rentenberger, C., and Abart, R.: The coherent solvus of disordered alkali feldspar determined with atom probe tomography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18335, https://doi.org/10.5194/egusphere-egu24-18335, 2024.

In the drive to develop more fuel-efficient aircraft engines to reduce the environmental impact of flying, engines are being designed to run much hotter. This is leading to a greater range of damaging interactions between the engine components and mineral dusts ingested into the engine during flight. To mitigate the effects of these interactions there is a critical need to understand mineral transformations (e.g., polymorphic changes, melting, glass transition), reactions, and mineral properties under much more extreme rates of heating and cooling than have been examined previously. Recent technological advances allow differential scanning calorimetry (Flash DSC) measurements to be made on small samples at temperatures of up to 1000 ℃, at heating/cooling rates of up to 50000 K/s, rates which comparable to those experienced by mineral dust particles inside a jet engine. Here we present two case studies, relevant in the engine context, that illustrate the capabilities of Flash DSC measurements.

A number of minerals ingested into aircraft engines undergo polymorphic transformations as they are rapidly heated inside the engine and these can have a profound effect on the accumulation rate of dust deposits on engine components. In our first case study we show the effect of heating/cooling-rate on the α - β-quartz transformation at rates between 10 to 10000 K/s (ambient pressures). During heating the temperature of the transformation increases from 573 to 608 ℃ over this heating-rate range, and the kinetics of the transformation are significantly modified.

Dust deposits may undergo melting inside an engine and infiltrate the porous coatings that are applied to engine components for thermal protection. This prevents the coatings expanding and contracting in response to temperature changes which, in turn, leads to their failure. Hence a knowledge of the viscosity of the melts (and hence infiltration-rate) and how this varies with temperature is important. Conventional methods of measuring viscosity are unable to access a considerable temperature range in which changes occur within the sample (e.g., crystallization) over the timescale of the measurement. The temperature dependence of viscosity may, however, be obtained from the heating-rate dependence of the glass transition temperature, and this is a measurement that can be made extremely rapidly by Flash DSC. In the second case study we show the temperature-dependence of viscosity over a temperature range previously inaccessible, for two CMAS melts that have compositions representative of those that are found in aircraft engines.

How to cite: Bai, Y., Covey-crump, S., Bojdo, N., Jones, M., and Pawley, A.: Differential scanning calorimetry measurements of mineral transformations at the extreme heating and cooling-rates experienced by mineral dusts ingested into aircraft engines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18687, https://doi.org/10.5194/egusphere-egu24-18687, 2024.

Dedolomitization is a geological process where dolomite undergoes transformation into calcite via the influx of aggressive Ca-rich solutions derived from various sources (e.g., evaporite dissolution). This conversion can take place in diverse environments. Our study focuses on a unique occurrence of dedolomite within a cave environment in the Mravljetovo brezno v Gošarjevih rupah cave located in central Slovenia. The cave walls exhibit distinctive yellowish and reddish crusts and covers that originated from dedolomitization process developed within this cave system.

Macro- and microscopic observations reveal that yellowish lithologies are of sedimentary origin, where dominating dedolomite (i.e., replacive calcite) is associated by mainly detrital particles with a high content of quartz, muscovite, clay minerals, and lithoclasts. In contrast, red lithologies are associated with the transitional zone between sedimentary layers and the host rock dolomite, featuring peculiar calcite crystals with abundant pore space and intercrystalline iron oxides and clay. The transitional zone itself consists of a calcite mosaic with smaller dolomite remnant embedded within the calcite structure.

The primary objective of this study is to conduct a comprehensive mineralogical analysis (XRD, SEM-EDS, EMPA, μXRF, CL, and Raman spectroscopy), aiming to recognize their interrelationships and utilize them as proxies for understanding the processes leading to dedolomitization.

Dedolomitization is evidenced by the abundance of corroded dolomite rhombs infilled with calcite, coupled with the development of moldic (dissolution-related) porosity, and subsequent crystallization of vein calcite. Detrital quartz reveals embayed crystal boundaries, as well as rounded lithoclasts enriched in clay-group species (e.g., illite). Subordinate detrital apatite, rutile, and zircon were also recognized. Besides, some mineral phases of authigenic origin were detected based on their habits and textural relationships. These include clay-group species (i.e., kaolinite, illite, and/or possible mixed-layer clays), as well as S- and Na-rich apatite, and fluorite. The formation of dedolomite was followed by the decrease of Mg and increase of Fe as evidenced by elemental mapping. These changes can reflect oxidizing conditions and subsequent precipitation of Fe³⁺ in hematite or goethite/lepidocrocite mineral phases that stained dedolomitized regions red to yellow.

Furthermore, we seek to investigate the potential influence of these mineralogical dynamics on cave formation and speleogenesis. All these findings can contribute to a better understanding of geological and geochemical mechanisms governing dedolomitization processes within cave environments.

This work is funded by the Slovenian and Polish research agencies (ARRS and NCN) through the bilateral Polish-Slovenian research project CEUS (project code in Slovenia: N1-0226; project code in Poland: 2020/39/I/ST10/02357).

How to cite: Gaidzik, K., Šarc, F., Ciesielczuk, J., Martín Pérez, A., Košir, A., Otoničar, B., Powolny, T., Tyc, A., Johnston, V., and Gebus-Czupyt, B.: Mineralogical study of dedolomitization in cave environments –the Mravljetovo brezno v Gošarjevih rupah cave, central Slovenia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19040, https://doi.org/10.5194/egusphere-egu24-19040, 2024.

A fundamental observation regarding oceanic subduction systems is that the starting material of subduction (MORB) is less oxidized than a major end-product (primitive magma in arcs), likely as a result of infiltration of mantle source regions by oxidized components from the subducted slab. Important redox-sensitive elements in slabs are S, C, H, and transition elements such as Fe and Mn. Fe is important because it is volumetrically significant, and release of other redox agents by dehydration reactions in subducted altered oceanic crust is controlled in part by Fe³⁺/∑Fe. Lawsonite (Lws) and epidote-group minerals (EGMs) are hydrous Ca-Al silicates that are key phases in subduction-zone H₂O and element cycling owing to their composition and abundance, and the Lws-EGM transition has been linked to significant changes in fluid composition. Fe is a major component in most EGMs and a more minor but common component in Lws. Fe in Lws and metamorphic EGMs is generally assumed to be entirely Fe³⁺ that substitutes for Al in octahedral sites. However, results of Fe-XANES analyses for Lws and EGMs in blueschist and eclogite were acquired at the European Synchrotron Radiation Facility and show a wide range of Fe³⁺/∑Fe. Results for Lws appear robust because there are no signs of beam damage during analysis and there does not appear to be a strong orientation effect (linear dichroism). EGMs similarly show no beam damage effects but, in contrast to Lws, show significant variation in XANES spectra and resulting calculated Fe³⁺/∑Fe as a function of orientation. Although Fe in some Lws analyzed is entirely Fe³⁺, Lws and EGMs from New Caledonia blueschists contain substantial Fe²⁺. Work is in progress to determine what controls Fe³⁺/∑Fe in Lws and EGMs, but a preliminary conclusion is that Fe²⁺ in these phases in subducted oceanic crust may be greater than currently known, with implications for phase equilibria calculations and understanding of subduction redox conditions and processes.

How to cite: Whitney, D., Hanel, S., Wilke, M., and Rosa, A.: Variation in Fe2+ / Fe3+ in hydrous silicates in subducted oceanic crust, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20603, https://doi.org/10.5194/egusphere-egu24-20603, 2024.

The Mahakoshal Supracrustal Belt (MSB) marks the northern margin of the Central Indian Tectonic Zone (CITZ) along which are sutured the northern and southern crustal blocks of India. Monazite U-Th-Pb total ages in the Dudhi granite from a sample at the southern margin of the MSB are reported here. Although the age of the MSB was constrained between 1.8 and 2.2 Ga, a more precise upper age limit of ~2.1 Ga was proposed later. The present sample shows signatures of extensive hydrothermal alteration resulting in the replacement of orthoclase by oligoclase accompanied by precipitation of carbonate and microcrystalline silica. The monazites yield seven age peaks starting from 2053±65 Ma to 1457±39 Ma, suggesting multiple resetting of the ages. The most intense peaks are at 1951±19 Ma (n=29), 1851±20 Ma (n=20) and 1787±25 Ma (n=12), with only three points in the 2053±65 Ma population. Most likely, the Dudhi granite represents partial melting of the basement to the MSB at 2053±65 Ma and constrains the maximum age of the MSB, corroborating the upper age limit suggested earlier.

How to cite: Mondal, A., Mallick, S. P., and Pruseth, K. L.: Monazite age constraint on the Mahakoshal Supracrustal Belt, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-136, https://doi.org/10.5194/egusphere-egu24-136, 2024.

The behaviour of rare earth elements (REE), U-Pb, Sm-Nd, and Sr-Sr isotope compositions in accessory minerals provides a unique opportunity to track fluid sources and investigate trace element mobilization during fluid-assisted metamorphism. Metapelites of the Southern Marginal Zone (SMZ), Limpopo Belt (Bandelierkop formation), South Africa, experienced a ca. 2.7 Ga granulite-facies event in which the rocks underwent anatexis. The southern portion of the SMZ contains dispersed fragments of retrogressed metapelites with ubiquitous amphibolite facies assemblages including biotite, orthoamphibole, kyanite and a 2^nd generation of garnet replacing cordierite, equilibrated under 660-600ºC and ≥ 0.6GPa. The hydrated metapelites contain graphite intergrown with the retrograde assemblages, indicating a mixed H₂O-CO₂ fluid and a rock-dominated system. However, the source of the fluids that caused the retrogression remains unclear. Previous studies suggested that hydrating fluids were originally internally derived from the crystallizing in-situ melts, in sediments containing biogenic graphite, or that an externally derived CO₂ and H₂O-bearing fluid infiltrated the metapelites through shear zone systems. For the latter, some studies have proposed that this occurred during uplift of the granulite directly after Neo-Archean peak metamorphism, while others have used rutile U-Pb ages of ca. 2.1 Ga to argue for Paleoproterozoic retrogression.

This study investigated the geochemistry of garnet, apatite, and monazite from the hydrated zone metapelites to understand the origin of the fluids. Garnet trace elements show two distinct populations described as Grt1 (Eu/Eu*=0.36) and Grt2 (Eu/Eu*=1.55). Monazite shows relatively homogeneous REE pattern for distinct samples with a slight variation in HREE and negative Eu anomaly (Eu/Eu*=0.20-0.38). As for apatite the REE pattern is variable and distinct within and between samples (Eu/Eu*=0.36-0.37). 2741 Ma to 2707 Ma U-Pb monazite ages suggest that the amphibolite-facies assemblages are mainly related to the ca. 2.7 Ga granulite-facies event. U-Pb apatite dating yielded younger ages ranging from ca. 2057 Ma to 2047 Ma. Sm-Nd isochron of apatite yielded an initial ¹⁴³Nd/¹⁴⁴Nd (0.50950 ± 0.00100; 2s; n = 21; MSWD = 4.6) equivalent, within uncertainties, to the monazite initial ¹⁴³Nd/¹⁴⁴Nd (0.50882 ± 0.00030; 2s; n = 30; MSWD = 0.81). Monazite and apatite preserved its primary 2.7 Ga Sm-Nd isotope signature, but the U-Pb apatite system was reset at ca. 2.05Ga by solid-state diffusion. Thus, apatite reacted in the presence of a disequilibrium fluid in the Neo-Archean, as evidenced by the REE chemical variation, but did not experience dissolution/reprecipitation processes.  

We propose that the retrogressed zone of the SMZ experienced a Neo-Archean peak granulite-facies followed by amphibolite-facies retrogression, in which an internally derived fluid interacted with the metapelites. This is supported by published Sm-Nd bulk rock compositions that follow the same evolution trend as these samples, indicating a closed system history in the retrogressed zone of the SMZ. The rocks also record a Paleoproterozoic, lower-temperature, amphibolite-facies re-heating event, responsible for the resetting of the apatite. Initial ⁸⁷Sr/⁸⁸Sr = 0.7130±0.0014 (2s; n = 19; MSWD = 13) indicates a continental origin for the fluids that crystallized the apatite.

How to cite: Mazoz, A., Stevens, G., Moyen, J.-F., Gonçalves, G., Ferreira, A., and Santos, R. V.: Unravelling fluid-rock interaction in the hydrated zone of the Southern Marginal Zone of the Limpopo Belt - South Africa: a geochemical investigation based on U-Pb geochronology and Sm-Nd isotope composition of monazite and apatite in metapelites , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-791, https://doi.org/10.5194/egusphere-egu24-791, 2024.

Calcite is a common syn-kinematic precipitate in upper crustal fault zones coating slickensides, forming slickenfibers, and infilling veins. Structural and geochemical analyses of fault-related calcites can be used to unravel the source, distribution, and mixing of parental fluids in association with past fault activity. Identifying deeply sourced fluids through syn-kinematic calcites is of paramount importance, as the correlation of the ascent of deep sourced fluids with strong earthquakes, may allow using hydrogeochemical modifications in groundwater as potential seismic precursors. In this study, we investigate the origin of syn-kinematic paleo-fluids that circulated along the Val d’Agri faults, in southern Italy. These faults bound an intermontane basin topping the largest onshore oil field in Western Europe. Since the Val d’Agri Basin is affected by natural seismicity and low magnitude oil production induced earthquakes, it is necessary to assess the potential threats of hydrocarbon fault leakage at shallow crustal levels. With this aim, we collected about 350 syn-tectonic calcites along high-angle extensional-transtensional fault zones. By combining macro- and micro- scale structural observations with carbonate isotopes (C, O, clumped, and Sr) and rare earth elements and yttrium (REY) geochemistry, we identified 5 fluid sources: (1) meteoric waters in geochemical and thermal disequilibrium with the host rocks, which interacted with superficial soil; (2) meteoric waters in geochemical disequilibrium and thermal equilibrium with the host rocks, which had limited interaction with the host rocks; (3) buffered fluids in geochemical and thermal equilibrium with the host rocks; (4) high temperature fluids in geochemical equilibrium and thermal disequilibrium with the host rocks, which ascended from the carbonate hydrocarbon reservoir; (5) hot meteoric waters in thermal and geochemical disequilibrium with the host rocks, which mixed with the deeply sourced fluids. The presence of multiple fluids is consistent with an open fault-related circulation system, which allowed mixing of shallow and deep fluids through the high-angle extensional-transtensional Val d’Agri faults. Given the societal and economic issues of this area, the recognized involvement of deep fluids during past fault activity is crucial for the context of oil exploration and production as well as for environmental monitoring. Furthermore, this suggests that the Val d’Agri Basin is an ideal region to explore fluid-fault relationships throughout the entire seismic cycle through local seismicity records and continuous groundwater monitoring.

How to cite: Schirripa Spagnolo, G., Bernasconi, S., Aldega, L., Castorina, F., Agosta, F., Billi, A., Prosser, G., Smeraglia, L., and Carminati, E.: The Isotope and REY geochemistry of fault-related calcites document syn-kinematic fluid distribution along the Val d’Agri faults (southern Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1982, https://doi.org/10.5194/egusphere-egu24-1982, 2024.

Magmatic activities in sedimentary basins provides abnormal heat sources and exert significant impact on the regional temperature field. In previous studies, the anomalous thermal effects of magmatic activities of multiple scales were studied. Small-scale intrusions (cm-m) can conduct high-temperature thermal baking of surrounding strata within tens to hundreds of meters. Basin-scale heat flow anomalies caused by mantle plume upwelling have also received increasing attention. In contrast, the thermal effects of large igneous plutons (several km to tens of km) have received little attention. A few studies have shown that the large intrusive bodies can affect the temperature field within a range of tens of kilometers. The Permian large igneous province is widely distributed in the Tarim Basin, forming several large plutons. The Manalik pluton is a large intrusive body in the northwestern Tarim, with a long diameter of up to 40 km. We have measured the clumped isotope of different calcite fabrics from the Ordovician carbonate intervals surrounding the contact aureoles of Manalik pluton. In-situ U-Pb dating will be applied to these fabrics to provide starting anchors for thermal history modeling using solid-state reordering models of carbonate clumped isotope. In addition, Silurian sandstones from the same area were collected for zircon (U-Th)/He age measurement and subsequent thermochronological thermal history inversion. Compared with conventional thermal indicators applied in deeply buried strata (e.g., vitrinite reflectance), the integration of the two thermochronological tools (Δ47/U-Pb and zircon U-TH/He) holds the advantage in more accurately quantifying the abnormal thermal effects of kilometer-scale intrusive bodies. The experimental results show that zircon (U-Th)/He and clumped isotope jointly constrain temperatures exceeding 200°C in Well Shengli 1 and Well Yingmai 35, which are closest to the Manalik pluton; the thermal anomalies identified in Well Yudong 2 are as high as 220°C; Well Yingmai 2 Well and Yingmai 34, which are far away from the igneous intrusion, were not affected by the thermal contact aureoles of Manalik pluton during the Permian period, and the current burial temperature is the highest paleogeothermal temperature experienced in historical periods. Based on the zircon (U-Th)/He and U-Pb/Δ47 simulation results, we reveal that the Manalik pluton has a significant thermal baking effect on the area within 20km, and the maximum temperature in the area close to the igneous pluton can exceed 220°C. The results of this study provide typical cases and inspiration for identifying and quantifying the thermal effects of contact aureoles in other basins where large igneous pluton are developed.

How to cite: Maimaiti, A., Tian, J., Cong, F., and Wang, Q.: Quantifying the anomalous thermal effects of contact aureoles of a large pluton in the Tarim Basin: Constraints from clumped isotope thermometry, in situ calcite U-Pb dating, and zircon U-Th/He thermochronology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2777, https://doi.org/10.5194/egusphere-egu24-2777, 2024.

The Tethyan Phosphogenic Province is one of the widest of its kind, representing an outstanding period of phosphate deposition principally in the Upper Cretaceous-Eocene period. The main aim of this study is to compare the Turkish phosphorites occurring along the southern side of the Neo Tethyan Ocean due to suitable seawater temperature and upwelling oceanic currents with Albanian phosphorites were deposited in higher latitudes and colder climates, in the same ocean. The Şemikan (Türkiye) phosphorites consist mainly of cream-coloured (CCP) and locally reddish phosphorites (RP) occurring as lenses or concordant blankets within high-grade cream phosphorites. Based on microscopic examination, cream-coloured phosphorites consist of phosphatic pellets, intraclasts, bioclasts (fossilized shark teeth, ostracods etc.) and nonphosphatic components, with texture changing from wackestone to packstone, testifying shallow marine depositional environment. Whereas, Gusmari (Albania) phosphorites consist of laminated phosphorites (LP), of mudstone/wackestone texture, with planktonic foraminifera Globotruncanidae, where the phosphate is sedimentary, and alternating laminae of phosphate and pelagic carbonate. Besides this, under SEM-EDS, 5µm crystals of the major ore of uranium, UO₂, were evidenced for the first time in LP. The mineralogical analyses showed that the CCP consisted of carbonate-rich fluorapatite, minor calcite and quartz. The RP consisted predominantly of carbonate-rich fluorapatite, hydroxyapatite, montmorillonite, and minor quartz. The LP consisted predominantly of calcite, carbonate-rich fluorapatite, hydroxyapatite, and traces of quartz. The mean P₂O₅ content of the CCP is 29%, RP and LP 14%, which is lower than that of other well-known global phosphorite deposits. The CaO content of the CCP, RP and LP ore is also higher than that of other global deposits because of a calcite matrix between phosphorite pellets. Based on preliminary results of trace elements CCP, RP and LP show a general trace element scarcity compared to the trace element averages of the world’s average phosphorites. The main reason for this deficiency is the rapid sedimentation or high burial rate in the sedimentary basin, which prevents the replacement of carbonate-rich fluorapatite by trace elements.

How to cite: Fociro, A., Öztürk, H., Sinojmeri, A., Cansu, Z., Moisiu, L., Çelik, Y., Nazaj, S., and Prifti, I.: Petrographic and Geochemical Analysis of Upper Cretaceous Phosphorites in Şemikan, Turkey and Gusmari, Albania: Insights into Depositional Environments and Palaeoceanographic Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2875, https://doi.org/10.5194/egusphere-egu24-2875, 2024.

Crystals grow in supersaturated solutions. A mysterious counterexample is dolomite CaMg(CO₃)₂, a geologically-abundant sedimentary mineral that does not readily grow at ambient conditions, not even under highly supersaturated solutions. Using atomistic simulations, we show that dolomite initially precipitates a cation-disordered surface, where high surface strains inhibit further crystal growth. However, mild undersaturation will preferentially dissolve these disordered regions, enabling increased order upon reprecipitation. Our simulations predict that frequent cycling of a solution between supersaturation and undersaturation can accelerate dolomite growth by up to seven orders of magnitude. We validate our theory with in situ liquid cell TEM—directly observing bulk dolomite growth following pulses of dissolution. This mechanism explains why modern dolomite is primarily found in natural environments with pH or salinity fluctuations. More generally, it reveals that the growth and ripening of defect-free crystals can be facilitated by deliberate periods of mild dissolution. [Kim et al., Science: adi3690 (2023)]

How to cite: Sun, W.: Dissolution enables dolomite growth near ambient conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3567, https://doi.org/10.5194/egusphere-egu24-3567, 2024.

The Rb-Sr dating system has long been recognised as being susceptible to thermal perturbation. Its so-called closure temperature (T_C) in biotite, the lowermost temperature at which interstitial diffusion of radiogenic ⁸⁷Sr is no longer facilitated, is ca. 400 ˚C, much lower than e.g., the commonly used U-Pb system in zircon in excess of 900 ˚C. Newly developed in-situ analyses or Rb-Sr isotope systematics in biotite using a collision cell mass spectrometer (ICP-MS/MS) have now enabled rapid dating using multiple grains and with high spatial resolution (on a single grain scale). This now allows making use of the thermal characteristics of this dating tool. However, the modes and degrees of isotope reset are still poorly understood. Here, we analyse rocks from the Kohler Range in Antarctica for their Rb-Sr systematics in biotite. The plutonic rocks formed as part of the active Permian Gondwana margin (ca. 280-260 Ma). Whilst two samples record their original Permian age, two other samples yield cretaceous ages (~100 Ma), consistent with regional magmatic activity during the breakup of Gondwana. Two samples with mixed populations of micas confirmed a partial reset in this rock, and thereby the full reset for the Cretaceous ages. An intriguing aspect is that reset is predominant in spot analyses with higher Rb/Sr, making these sections apparently more prone to thermal reset, likely through higher diffusion potentials. We interpret the resetting of the system as a response to thermal perturbation of the igneous rocks with no apparent petrographic footprint. It is demonstrated that in-situ Rb-Sr dating of igneous micas in plutons can be used to date magmatic flare-ups in rocks that can be hundreds of millions of tears older. The technique thus holds immense potential to decipher the thermal histories of terranes that otherwise remain undetected and may be used to shed new light on a large number of suspect Rb-Sr (mixed?) ages with no apparent geologic meaning.

How to cite: Nebel, O., Ali, Z., and Raveggi, M.: Magmatic flare-up recorded in Rb-Sr reset-ages during Gondwana break-up, Kohler Range, Marie Byrd Land, Antarctica , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4508, https://doi.org/10.5194/egusphere-egu24-4508, 2024.

Phosphorites are well-known, worldwide, for accommodating a significant amount of U relative to other sedimentary rocks, due to the crystal structure of apatite where U substitutes Ca. In Albania, uranium-bearing Lower Jurassic phosphorites form a distinctive horizon identified across the entire Ionian zone. Two different types of U-bearing phosphatic deposits are identified within the Lower Jurassic carbonate succession in Albania; one, stratigraphically younger, layered and parallel to carbonate strata and the other due to infiltration in older, brecciated carbonates. The first type consists of lenticular shape deposits of limited lateral extension intercalated in thin-shelled bivalve packstone/rudstone, possibly corresponding to the Toarcian Bositra-rich organic rich “Posidonia” shales of Austria and Germany. The phosphatic horizon is confined by dark gray J₂ limestone on the top, while the bottom shows signs of an early erosion. Their extent varies from 5-10 m to 100-160 m, while their thickness varies from 0.3 to 6 m. The radioactivity measurements indicate that the intensity of gamma radiation varies from 0.6 to 1.66 µSv/h, while the uranium content varies from 50 to 230 ppm, the highest values corresponding to the P₂O₅ peak of 32.66%. The second type of phosphorite mineralization developed in a widespread horizon throughout the Ionian zone. Its extension varies from 1.5 to 8 km, composed of continuous zones up to 0.5-1 km with some small interruptions. Uranium-bearing phosphatic deposits occur as the infiltrated matrix of breccias (caused by hydraulic or tectonic stress, not of sedimentary origin) made of angular clasts of Pliensbachian inner carbonate platform facies of the J₁ (peloidal and oncoidal packstone/grainstone with Siphovalvulina foraminifers and Palaeodasycladus mediterraneous dasyclad algae). The intensity of gamma radiation varies from 0.5 to 1.1 µSv/h, uranium content varies from 50 to 150 ppm and the P₂O₅ highest peak is 15%. In accordance to the first data achieved, the uranium-bearing phosphorites of Early Jurassic age in Albania formed in deep, oxygen-depleted marine conditions as suggested by the abundance of thin-shelled bivalves. The well-documented early Toarcian Oceanic Anoxic Event driven by an increase in nutrients linked to high volcanic emissions of CO₂ may have favoured the formation of the phosphate deposits. The intensive tectonic events associated with the Alpine Tethys Ocean opening during the Early and Middle Jurassic should be the main factor causing the brecciation and controlling the formation of later infiltration mineralization.

How to cite: Sinojmeri, A., Fociro, A., Della Porta, G., Grieco, G., and Beqiraj, S.: Preliminary insights on uranium-bearing Jurassic phosphorites of the Ionian zone, Albania, their distribution and genesis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5344, https://doi.org/10.5194/egusphere-egu24-5344, 2024.

The Dizi series formed on the southern passive margin of a small oceanic basin on the Southern Slope of the Greater Caucasus and is exposed in the structural zone of the same name. The series is composed of metaterrigenous phyllite-like and volcanogenic rocks of the Devonian-Triassic age; marbles also are quite widespread in the series. During the Variscan orogeny, all rocks of the series underwent low-temperature regional metamorphism; later, in the Middle Jurassic time, intensive contact metamorphism took place. The object of presented research is marble, found in the rocks of the series both in the form of lenses and blocks. Interest in the study of marbles spread in the Dizi series is caused by several factors, namely, there is still no consensus on the position of marbles in the series, their detailed geochemical study has not been carried out, and the conditions of their formation have not been determined. There is an opinion that the Dizi series represents part of the Triassic Upper Karakaya complex, which was probably deposited in the forearc of the southern margin of Laurasia. The marbles are included in the series as exotic blocks of shallow marine Carboniferous and Permian limestone, most likely formed in Gondwana. During the study of the Dizi series marbles petrographic and geochemical research methods were applied. Petrographic characteristics of the marbles from all outcrops show a similar mineral composition, and structure and texture as well. The authors analyzed the main components, RE, and REE of the Dizi series marbles. The ratios Ca VS Mg, Mg/Ca VS SiO₂, and Sr VS Mg/Ca show that the protolith of the marbles was pure limestone. The reconstruction   of the deposition conditions of the marble protolith, based on the concentrations of Sr, Rb, and Ba, indicates the formation of limestones in the conditions of the continental margin. The Ce-negative anomaly observed in the marble samples is possibly due to the existence of an oxygenated marine environment, probably of shallow water conditions. These conditions fully correspond to the tectonic interpretation of geochemical data from other metasedimentary rocks of the series. The results of the presented studies confirm that the marbles under consideration were formed in situ, together with the other rocks of the Dizi series in the conditions of the continental slope and its foot on the southern passive margin of a small oceanic basin of the Southern Slope of the Greater Caucasus.

How to cite: Javakhishvili, I., Tsutsunava, T., and Beridze, G.: About the marbles of the Dizi series (Greater Caucasus): geochemical features, the nature of the protolith, and paleoecological conditions of their formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5609, https://doi.org/10.5194/egusphere-egu24-5609, 2024.

Microbialite development in the Ediacaran Qigebrak Formation of the Tarim Basin, Northwest China: An examination of characteristics, distribution, and paleoceanographic reconstruction

Xudong Chen^1,2, Qilu Xu^1,2

• National Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao 266580, China;
• School of Geosciences, China University of Petroleum (East China), Qingdao, 266580, China

The Upper Ediacaran Qigebrak Formation in the Tarim Basin of NW China preserves abundant and well-preserved microbialites with primary textures. These provide valuable insights into Precambrian sedimentology and paleoceanography. Our study focuses on elucidating the relationship between paleoceanic conditions and the development of these microbialites to understand their Precambrian origin.

A comprehensive analysis of Ediacaran outcrops in the northwestern Tarim Basin identified 12 distinct microbialite types, ranging from mafic (F1) to flat-laminated stromatolite (F12). These comprise F2 (micrite dolomite), F3 (granular dolomite), F4 (bonded sand debris dolomite), and spongiomicrobialite variants (F5-F7). Additionally, we observed F8 (fenestral tectonic thrombolites), F9 (micrite thrombolites), and diverse stromatolite dolomites (F10-F12). Their occurrence is spatially distributed: F1 and F2 in the nearshore supratidal low-energy zone; F3, F4, and F7 in granular beach and microbial mound zones; F5 and F8 in the environmental transition zone; F6 and F11 in the lower intertidal high-energy zone; F10 predominantly in the upper subtidal high-energy zone; and F9 and F12 in both upper intertidal and lower subtidal low-energy zones.The shale-normalized REE patterns of these microbialites exhibit weak negative Ce anomalies, weak positive Eu anomalies, and positive La anomalies, suggestive of suboxic seawater deposition. Their chemical signatures, characterized by low V, Ni, and Co concentrations, high Sr content, and Sr/Cu ratios exceeding 50, collectively indicate warm and arid paleoclimatic conditions. Compared to F9, F6, F10, and F11 show lower V/(V+Ni) values, higher Mg/Ca ratios, and stronger LREE and MREE deficits, suggesting formation in shallower, more dynamic, saline, and oxygenated waters.

Our findings offer fresh perspectives on the formation mechanisms of Precambrian microbial rocks and paleo-oceanic reconstruction.

How to cite: Chen, X. and Xu, Q.: Microbialite development in the Ediacaran Qigebrak Formation of the Tarim Basin, Northwest China: An examination of characteristics, distribution, and paleoceanographic reconstruction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5704, https://doi.org/10.5194/egusphere-egu24-5704, 2024.

Dating Quaternary carbonates and phosphates beyond the range of U-series geochronology is challenging, but recent studies have shown potential using the method of LA-ICP-MS U-Pb geochronology. Terrestrial materials altered and produced by pedogenic processes are particularly challenging, as they are usually rich in common Pb and poor in U; however, they provide some of the rare opportunities to directly date important archaeological artefacts. Our aim is to advance the age constraints of the hominin presence in the Zarqa Valley, Jordan, an important geomorphological feature with the oldest hominin artefact outside Africa. Along with new Ar-Ar geochronology of sequence-bounding basalts and new palaeomagnetic constraints, our approach is to: (1) review published U-Pb data of 2019; (2) conduct LA-ICP-MS U-Pb analyses in various pedogenic carbonates (calcrete) that cap the artefact-bearing deposits along with mammoth fossil remains; and (3) review the regional ²³⁴U/²³⁸U activity ratio estimate required for calculation of accurate U-Pb ages.

A previous attempt to date hominin artifacts in the valley yielded an age of 1.98 ± 0.20 Ma for calcrete material, which is a weighted mean of several individual U-Pb isochrons derived from laminated calcretes, cracks, pore spaces and cement, and corrected by an initial ²³⁴U/²³⁸U activity ratio of 1.5 ± 0.5. We calculated an alternative, statistically favourable, age based on pooling the data into a single Tera-Wasserburg regression, resulting in 1.93 ± 0.44 Ma.

Our LA-ICP-MS analysis thus far has not yielded a new significant age, but we have focussed on understanding the U and Pb compositions in a range of materials, including calcretes, rhizoliths, fossil coatings and Mammalian fossils. Biogenic spherulite laminae in laminar calcrete have higher U (0.56 ± 0.064 ppm) and lower Pb contents (0.61 ± 0.15 ppm) compared to abiogenic cracks and cement (0.33 ± 0.084 and 0.9 ± 2 ppm, respectively). Although far from desirable for U-Pb geochronology, for now, the spherulite laminae seems to be the most suitable micromorphology to date calcrete. Coarse spar of rhizoconcretions have very low U contents (0.07 ± 0.35 ppm), leading to unfavourable U/Pb ratios. Two fragments of a mammoth molar from an artefact-bearing deposit have been analysed; one is part of the crown having dentine and enamel, and the other one is dentine of the root. The crown and root fragments have high U concentrations of 33 ± 11 and 13.7 ± 9.9 ppm, respectively, but with their high Pb contents they still yield a low spread in U/Pb ratios and very imprecise lower intercept ages. Using LA-ICP-MS mapping to better identify areas of alteration, we pooled U-Th-Pb spot data from regions with low Y (<5 ppm), Mn (<50 ppm), Al (<100 ppm), Th (< 0.05 ppm) and high P (> 7200 ppm), which correlated with the central portion of the dentine. These data yielded an age, using the combined U-Pb and Th-Pb calculation, of 1.9 ± 1.1 Ma; although very imprecise, it shows potential for further refinement.

How to cite: Cerqueira, J. C., Roberts, N. M. W., Scardia, G., Parenti, F., Ladeira, F., and Neves, W.: U-Pb geochronology of Quaternary pedogenic carbonates and teeth from archaeological sites of Zarqa Valley, Jordan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5861, https://doi.org/10.5194/egusphere-egu24-5861, 2024.

Detrital geochronology is a powerful tool to interrogate the sedimentary archive of (paleo-)hinterland tectonism, metamorphism, and exhumation, and can also be applied to modern river sediment as a first-pass tool to establish regional bedrock ages. The popular zircon U-Pb detrital geochronometer has seen widespread adoption for these tasks (4,173/5,100 results for the search term detrital geochronology also contain the term zircon U-Pb; Clarivate Analytics Web of Science). However, zircon fertility is strongly biased to intermediate to felsic source rocks. Moreover, zircon crystallization is volumetrically limited in metamorphic terranes which do not achieve anataxis (e.g., Moecher & Samson, 2006), and is typically restricted to rim overgrowths which are vulnerable to mechanical destruction during fluvial transport, and which are challenging to detect and analyse (e.g., Campbell et al., 2005).

Therefore, it is desirable to develop complementary provenance tools for sub-anatectic settings, as well as tools targeting more abundant rock-forming minerals for use with small-volume samples (e.g., drillcore). Established alternative detrital phases include the U-Pb system in apatite, monazite, titanite, and garnet. The advent of LA-ICPMS systems equipped with mass-filtered online reaction cells now also permits the routine use of β-decay systems by overcoming parent-daughter isobaric interferences. These include Lu-Hf in garnet and apatite, and Rb-Sr in K-phases including K-feldspar and mica (Rösel & Zack, 2022; Woods 2016). K-phases are also amenable to conventional Ar-Ar detrital geochronology.

Here, we present case studies of emerging detrital provenance techniques, with particular application to modern and past orogenic systems.

Campbell, I., et al., 2005. Earth Planet. Sci. Lett. 237, 402-432,  doi: 10.1016/j.epsl.2005.06.043

Moecher, D., & Samson, S., 2006, Earth Planet. Sci. Lett. 247, 252–266, doi: 10.1016/j.epsl.2006.04.035

Rösel, D., & T. Zack, 2022. Geostandards and Geoanalytical Research 46.2, 143-168, doi: 10.1111/ggr.12414.

Woods, G. 2016. Agilent Application Note. Agilent Technologies, Cheadle.

How to cite: Mark, C., Neofitu, R., O'Sullivan, G., Glorie, S., Zack, T., Rösel, D., Barfod, D., Chew, D., Daly, J. S., Clift, P., and Najman, Y.: Mountains from sand grains: Advances in detrital provenance applied to orogens, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9818, https://doi.org/10.5194/egusphere-egu24-9818, 2024.

The fault system within petroliferous basins plays a pivotal role in governing the migration, accumulation, and preservation of oil and gas resources. Accurate determination of the timing of fault activities is critical for reconstructing the history of tectonic evolution and for the analysis of hydrocarbon systems. Conventionally, this determination is achieved through the analysis and interpretation of seismic data. However, this method's effectiveness is often constrained by the quality of the seismic data, typically yielding only an approximate timeframe for fault activity. This limitation poses significant challenges in precisely identifying the periods of fault activity, which is essential for the analysis of their impact on hydrocarbon accumulation. Calcite, a commonly developed vein mineral in response to fault activities, is noteworthy in this context. The use of LA-ICP-MS U-Pb dating for fault vein calcite has been established as an effective technique to reveal time information of fault activity. The Tuoputai area, situated within the Tarim Basin, is recognized as one of the exploration hotspots with a complex tectonic evolution history. In particular, the strike-slip faults connecting Lower Cambrian source rocks with Ordovician carbonate reservoirs are instrumental in hydrocarbon migration and accumulation. In this study, the TP39 fault zone in the Tuoputai area, recognized for its rich hydrocarbon content, was selected for detailed analysis. We initially analyzed seismic data to obtain the approximate period of fault activity, followed by LA-ICP-MS U-Pb dating of calcite veins from core samples, to precisely determine the fault activity time. Additionally, the study incorporated the analysis of oil fluid inclusions in the calcite veins to comprehensively analysis the impact of fault activities on hydrocarbon accumulation. The seismic data indicated that the TP39 fault zone has mainly experienced three activity periods, including the Caledonian (542-416 Ma) to Hercynian (416-251 Ma), Indosinian (251-199.6Ma) and Himalayan (65.5 Ma-present) periods. In situ U-Pb dating of calcite veins from Ordovician reservoir cores in two wells within the fracture zone yielded ages of 446.79±2.67 Ma, 443.63±1.31 Ma, and 278.23±2.11 Ma, defining two significant active events in the TP39 fault zone during the Late Caledonian (~440 Ma) and Late Hercynian (~280 Ma), respectively. Furthermore, fluid inclusion analysis in calcite veins revealed a high prevalence of yellowish-green and bluish-green fluorescent oil inclusions, followed by blue fluorescent oil inclusions. The corresponding Th results from coexisting water inclusions indicated that the mainly phases of crude oil charging occurred during the Late Caledonian and Late Hercynian periods, followed by the Himalayan period, correlating well with the U-Pb dating results. This indicated that the fault activity during the Late Caledonian and Late Hercynian periods opened pathways for crude oil migration from the source rocks to the reservoirs. This study used the absolute dating method to constrain the activity time of the fault, demonstrating its impact on hydrocarbon accumulation, which is of great significance to basin structural research and oil and gas exploration.

How to cite: Xie, H. and Tian, J.: Fault activity history under absolute age constraints and its impact on hydrocarbon accumulation: A case study of the Tuoputai area in the Tarim Basin, China , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10059, https://doi.org/10.5194/egusphere-egu24-10059, 2024.

The mantle section of the ophiolite sequence is composed of ultramafic rocks, abundant in magnesium silicates. When exposed to crustal depths, these minerals become thermodynamically unstable and often interact with fluids of different provenance and chemistry. Ophiolite-hosted carbonates are one of the most widespread secondary phases resulting from interactions between silicates and CO₂-rich fluids. There is ample evidence that carbonation of ultramafic rocks can occur in various geological settings and across a broad range of P-T conditions (Plümper & Matter, 2023). Therefore, accurately identifying the source of the fluids responsible for carbonation could contribute to a more comprehensive understanding of the long and complex evolution of the ophiolites.

In this study, we investigate carbonates hosted by the two ultramafic massifs (Szklary and Braszowice) of the Central Sudetic Ophiolite (CSO) (NE Bohemian Massif). This ophiolitic complex represents a late Devonian oceanic lithosphere formed in the slow-spreading regime. The complex story of the CSO includes prograde metamorphism, reaching its climax within the amphibolite facies, emplacement of syn- and post-Variscan magmas, as well as tropical weathering event(s) in the Cenozoic. Carbonate mineralization appears mostly as extensive veins and vein-like structures within partially serpentinized peridotites and serpentinites. The vast majority of veins in both localities exhibit a high modal abundance of cryptocrystalline magnesite accompanied by chalcedony or quartz. Field investigations revealed that carbonate veins containing magnesite-dolomite and calcite-dolomite are comparatively less common occurrences and they are mostly seen in the Braszowice ophiolitic fragment. In some samples, hydrous magnesium silicates co-occur with the studied carbonates. Based on both bulk and single-spot chemical composition (ICP-MS/ES and LA-ICP-MS) of carbonates, discrepancies and similarities have been observed between two ultramafic massifs. The concentrations of several trace elements (Ni, Al, Mn, Sr, Ba, Fe) noticeably vary between Szklary and Braszowice. Moreover, varied chemical compositions have been pinpointed among veins sampled at different depths. Strontium isotope composition was analyzed for fraction dissolved in HCl. At least two groups of carbonate veins can be distinguished based on their ⁸⁷Sr/⁸⁶Sr ratios. Veins sampled from the Braszowice pit floor, exhibiting Mgs or Mgs ± Dol or Cal ± Dol paragenesis, consistently display 0.7064 - 0.7065 values. Carbonate veins located at shallow depths in Braszowice and Szklary, primarily composed of cryptocrystalline Mgs or Mgs ± Qz, show ⁸⁷Sr/⁸⁶Sr values ranging from 0.7070 to 0.7113 suggesting input from fluids derived from the continental crust. Our research indicates a level of complexity in the formation of ophiolite-hosted carbonates including several stages of their formation as well as several sources of carbonating fluids.

Plümper, O., & Matter, J. (2023). Olivine—the alteration rock star. Elements, 19(3), 165-172.

Funding: Research financially supported by NCN PRELUDIUM project 2022/45/N/ST10/00879

How to cite: Cieślik, B., Pietranik, A., Kierczak, J., Lacinska, A., and Ettler, V.: Multistage carbonation of the Variscan ophiolite? Insights from geochemical and isotopic diversity of ophiolite-hosted carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11037, https://doi.org/10.5194/egusphere-egu24-11037, 2024.

Temperature is recognized as the only dominant factor that affects the opening and closing of isotope system, based on which thermochronology has well developed. However, there are some research shows that stress could also matter. The muscovite K-Ar ages of Sanbagawa (Japan) schists are consistently younger with increasing deformation extent (Tetsumaru, 1988), which revealed that tectonic deformation can have influence on isotopic ages. On a microscopic scale, elements like Pb can redistribute in zircon lattice during dislocation (Piazolo,2015). The behaviors of isotopic systems in dating minerals under stress involve the fundamental problem of isotopic chronology. The application of it can be very wide, it allows us to get the deformation age directly if we choose the right deformed minerals in the right way. Some of the works such as fault, fold and ductile shear zone dating by our lab has been published (Yu Wang, 2010, 2016, 2020). What role does stress play in isotope diffusion which in turn affects ages is what we are eager to know. We designed a set of experiments using three axles press to work on undeformed K-feldspars with known age (126Ma) to test the effects. Rock mechanics experiments, field observation and isotopic dating are combined to give us an insight to it.

How to cite: Chen, X. and Wang, Y.: Effect of tectonic stress on isotopic systems in dating minerals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11149, https://doi.org/10.5194/egusphere-egu24-11149, 2024.

The Bristol Channel Basin (BCB) is a small continental rift basin that developed along the eastern margin of the North-Atlantic during the Mesozoic. Relatively minor basin inversion occurred during the Cenozoic. It has been extensively studied due to the exceptional exposure of faults along both margins of the basin. Widespread calcite mineralisation of overprinting fracture networks documents fluid partitioning along these structures over time. However, the temporal evolution of deformation has been constrained solely from the relative timing of structures in the field and through comparisons with other basins in the region. This has made detailed modelling of how structures have evolved during basin development and later inversion problematic. In this study we succesfully use U-Pb carbonate geochronology on low U samples (<1ppm) to constrain the absolute timing of fault development, whilst also assessing fluid source evolution with stable isotope and fluid inclusion data. Absolute dating of calcite slickenfibres in the fault cores of extensional, thrust and strike-slip faults in the East-Quantoxhead - Kilve region reveals the precise timing of different phases of deformation within the BCB for the first time.

New age data show that extensional faulting occurred from ca. 154-118 Ma. Strike-slip faults formed ca. 47-21 Ma, with thrust faults forming ca. 46-35 Ma. The results show Late Jurassic – Early Cretaceous E-W extension with a vertical σ₁, followed by Eocene – Miocene N-S contraction with σ₁ now being ~horizontal. New age determinations provide much greater insight into the longevity of these structural phases, as well as how fluid nature and composition has evolved over time. Stable isotope data captures fluid source evolution, with δ13C & δ18O values being more negative in the older extensional faults, and becoming more positive over time in the later contractional features. Reactivated structures show evidence for deeper fluid sources, shown by relatively hotter fluid inclusion temperatures within these faults.

Constraining the development of different fault populations within the BCB increases our understanding of the evolution of regional stress within southern England and can be extrapolated to nearby basins. Understanding the historical partitioning of fluid flow through different fault populations has practical applications for understanding where produced and/or injected fluids will flow when a reservoir is exploited today, such as in an Enhanced Geothermal System (EGS).

How to cite: Connolly, J., Anderson, M., Mottram, C., Price, G., and Sanderson, D.: Using U-Pb Carbonate Geochronology to constrain the timing of fault development and fluid source evolution in an inverted continental rift basin., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11865, https://doi.org/10.5194/egusphere-egu24-11865, 2024.

Carbonates (calcite, aragonite, dolomite) are a minor component (often below 4 vol. %) of CM carbonaceous chondrites and formed during the aqueous alteration of their asteroidal parent bodies in the first few million years of Solar System history. The chemical and isotopic composition of these minerals are a valuable source of information on the conditions of alteration, potentially providing information on the composition and temperature of asteroidal fluids.

We report the carbon triple oxygen and carbonate clumped isotope compositions of six CM chondrites (Allan Hills 83100, Cold Bokkeveld, LaPaz Icefield 031166, Lonewolf Nunataks 94101, Murchison, Scott Glacier 06043), which span a range of degrees of aqueous alteration. To avoid issues due to the brecciated nature of these meteorites, gas aliquots produced by a single acid digestion were used to measure both the clumped isotopes and the triple oxygen isotope compositions. Where both calcite and dolomite are present, stepped acid dissolution allows us to measure their isotopic compositions separately.

We found that the Δ¹⁷O values range from -1 to -2.6‰, with a 0.6‰ difference between coexisting calcite and dolomite that indicates precipitation from distinct fluids. Crystallization temperatures range from 5 to 50⁰C for calcite and 75 to 100⁰C for dolomite. CM chondrites often contain several generations of carbonates with ranges in isotopic compositions that can be determined by ion probe. Because our method relies on the bulk extraction of carbonate phases, the measured values are the modes of the distributions for each meteorite, which has to be considered carefully in their interpretation. The isotopic composition of the alteration fluids can also be calculated for each meteorite and carbonate phase. We find that their δ¹⁸OvsSMOW ranges from -6.6 to +2.3‰, with no clear relationship with temperature or the δ¹³C of the carbonates, indicating a variety of starting isotopic compositions for the alteration fluids.

The main pattern that emerges is that chondrites with a higher degree of alteration (based on their petrology) have carbonates with lower Δ¹⁷O and higher crystallization temperatures, which is consistent with a prograde reaction in a largely closed system, and with dolomite forming after calcite in our samples.

How to cite: Clog, M., Lindgren, P., Lee, M. R., and Modestou, S.: The thermal and aqueous evolution of CM carbonaceous chondrite meteorites revealed by triple oxygen and clumped isotope compositions of their carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11910, https://doi.org/10.5194/egusphere-egu24-11910, 2024.

In south-western Martinique (Lesser Antilles), the Pointe Burgos Basaltic monogenetic strombolian cone and lava flow cut through a porphyritic dacitic lava dome (Morne Champagne) dated at 617 ± 52 ka (Germa et al., 2011). An exceptional feature of the basaltic lava flow is the occurrence of about 4% of large (up to 2 cm) quartz crystals. Previous studies suggested that quartz xenocrysts had been added to the basaltic magma upon mechanical magma mixing with the cooled shallow dacitic reservoir, with a 9:1 ratio. Indeed, plagioclase phenocrysts (>1 cm) present resorbed surface and reaction rims, a well-known evidence of crystal remobilization. However, no other textural evidence of magma mixing is visible in the basaltic edifice. Moreover, the quartz crystals present unusual habits, are heavily cracked, and appear as filling voids in the basalt. This led us to investigate the age of the basaltic eruption and of the quartz crystals to propose a scenario for the xenocrysts’ origin.

The groundmass of the basaltic lava flow was K-Ar dated at 379 ± 25 ka, therefore ~240 ka after the eruption of the dacitic dome that it cuts through. Such a long time difference suggests that magma in the shallow reservoir was completely solidified when the basaltic magma ascended through it. Therefore, we would have expected to see also enclaves of dacite included in the basalt. Thermoluminescence (TL) dating allows for estimating the time since mineral formation or the last heating of a mineral above ~350 °C, thus representing an ideal tool to test whether the quartz xenocrysts formed synchronously with lava flow, or if they were formed later as substitutional minerals or void fillings. Here, we used red TL in combination with several protocols for dose determination, yielding consistent results. For assessing the dose rate, we took into account the quartz xenocrysts’ size distribution, the radioelement concentration of the basaltic matrix and the sites’ erosive evolution. The latter is particularly important because the basaltic matrix is comparatively poor in radioactivity so that the share of the cosmic dose rate becomes important. We obtain preliminary TL ages of 345 ka (with a total erosion of 20 m) and 377 ka (with an erosion of 50 m), each with a ~7% uncertainty. This result emphasizes the importance of reconstructing the lava flow geometry for answering the research question. As we believe that scenario (1) is more plausible, our results indicate the xenocrysts were likely formed post-eruption, challenging the initially suggested model of magma mixing and favouring secondary precipitation or mineral substitution. In case of TL resetting through geothermal activity, the age would represent the cooling following its cessation. However, given the xenocrysts’ pseudomorphic habit, it appears more likely that they represent secondary precipitates from hydrothermal fluids in voids left by strong geothermal alteration of the basaltic host rock.    

References

Germa, A., Quidelleur, X., Lahitte, P., Labanieh, S., Chauvel, C., 2011. The K–Ar Cassignol–Gillot technique applied to western Martinique lavas: a record of Lesser Antilles arc activity from 2 Ma to Mount Pelée volcanism. Quat. Geochronol. 6, 341-355.

How to cite: Schmidt, C., Germa, A., Quidelleur, X., King, G., and Jaimes Gutiérrez, R.: Age and origin of quartz xenocrysts in a basaltic lava flow in Martinique , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13041, https://doi.org/10.5194/egusphere-egu24-13041, 2024.

Intrusions of the Navajo Volcanic Field (NVF) contain eclogite xenoliths that record processes related to the subduction of the Farallon plate beneath the Colorado Plateau. Previous geochronological work sparked controversies about their origin, especially whether they are derived from oceanic crust of the Farallon plate, or from older continental lithosphere, based on occasional Proterozoic zircon U-Pb ages. Moreover, the mechanisms and timescales of the recorded high-pressure processes, including several stages of fluid metasomatism, are largely unknown. We study the U-Pb systematics of garnet, zircon and rutile by LA-ICP-MS in order to achieve a refined petrochronologic interpretation of the NVF eclogites.

The eclogite xenoliths are hosted by serpentinized ultramafic microbreccia (SUM) which intruded the Colorado Plateau at ~30 Ma as a consequence of extensive hydration of the lithospheric mantle by Farallon slab-derived fluids. In contrast to kimberlite-borne eclogite xenoliths, which often contain garnet and omphacite only, those of the NVF additionally contain ubiquitous rutile, and often pyrite, phengite, zoisite pseudomorphs after lawsonite (with rare lawsonite relics), accessory monazite, and rare coesite. Based on this assemblage, peak P-T conditions around 4 GPa and 600°C are estimated. Subsequent rapid uplift in the sub-solidus SUM is not thought to have caused significant further heating. Except for a few instances where a mid-ocean ridge basalt-like bulk chemical composition is essentially preserved, the xenoliths are strongly overprinted by several metasomatic events in the eclogite facies. Most notably, this involved interaction with a Na-Si-S-rich fluid, probably of crustal origin, and a later (just prior to exhumation) serpentinite-derived fluid.

All our U-Pb rutile data as well as published U-Pb monazite data (~29 Ma) agree with the ~30 Ma SUM formation age. The majority of the U-Pb zircon analyses predate the rutile data by not more than several Myr, with a minority of older ages forming a continuum to the late Cretaceous. Unlike some earlier studies, we did not obtain any Proterozoic U-Pb zircon ages. The garnet U-Pb dates, which are mostly from pre-metasomatic zones, partly agree with the zircon dates within uncertainty, but sometimes predate the zircon dates from the same sample by up to several tens of Myr.

Despite moderate peak metamorphic temperatures (~600°C), rutile remained an open system for Pb until exhumation. Garnet and zircon are resistant to Pb volume diffusion at these temperatures, however, the zircon ages appear to be largely reset during fluid metasomatism, as also indicated by often high common Pb contents. Due to the absence of preserved igneous zircon ages, the protolith origin remains uncertain. Garnet, which grew mostly before metasomatism, seems to provide robust ages of initial eclogitization, which may have been diachronous in our sample suite. Geochronological evidence implies that several tens of Myr passed between initial eclogitization and exhumation of the xenoliths.

How to cite: Pohlner, J. E., Hao, S., Albert, R., Gerdes, A., Schulze, D. J., Helmstaedt, H., and Aulbach, S.: Garnet, zircon and rutile U-Pb systematics of eclogite xenoliths from the Navajo Volcanic Field (USA), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13231, https://doi.org/10.5194/egusphere-egu24-13231, 2024.

The Cryogenian period represents a critical interval in Earth’s history, characterized by drastic tectonic and environmental changes. Evidence of low-altitude glacial deposits from this time has been recognized globally, alluding to the most extensive icehouse regimes known on our planet. These conditions of successive global freezing and warming during the Neoproterozoic have been dubbed as ‘Snowball Earth’ events. Importantly, the Cryogenian may have played a key role in the accelerated evolution of early life, as microorganisms became more complex and abundant after this period. Consequently, it is important to constrain the absolute timing, duration, and termination of these glacial and interglacial events. Despite their significance, robust, direct dating of Cryogenian sections remains challenging. The most accurate way to constrain these units is through dating of interbedded volcanics. However, they are not present across all sections globally, making correlations difficult to establish.

As such, we present a novel strategy to address this issue by directly dating a broad array of Cryogenian carbonates through an in situ U-Pb mapping approach. Our case study includes inter-glacial and post-glacial carbonates from sections in Australia, Oman, and Greenland. We show that this method allows for the concurrent collection of geochemical, petrographic, and geochronological information at sufficient precision to address key geological questions. Geochemical proxies such as elevated Mn/Sr ratios and Al or Si can be used to filter areas affected by alteration or detrital input, respectively. Secondary phases such as veins and overgrowths can also be petrographically avoided as an advantage of the spatially coherent mapping technique. Regions that yield enrichment in U and best spread in U–Pb ratios can be preferentially selected. Triaging such datasets and spatial information can help identify subdomains within a sample that is most suitable for dating, maximizing the success rate of this approach. The technique is capable of yielding age precision of ±1% depending on the concentration of U, the range in radiogenic isotopes, and the number of pixels that make up an analytical point.  

How to cite: Subarkah, D., Collins, A., Löhr, S., Nixon, A., Blades, M., Farkas, J., Lloyd, J., Klaebe, R., Gilbert, S., and Virgo, G.: Direct dating of global Cryogenian sections by in situ U–Pb mapping of carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14298, https://doi.org/10.5194/egusphere-egu24-14298, 2024.

Carbonatite has enormous potential for rare earth element resources, typically enriched in light rare earth elements, and has attracted increasing attention from geologists and economists. However, there are a small number of documented instances of carbonatite-related heavy rare earth elements enrichment. The Jialu carbonatites in the Qinling orogenic belt (central China) are characterized by the enrichment of heavy rare earth elements compared with typical global carbonatites. The carbonatites are dominantly comprised of calcite, quartz, sulfate, K-feldspar, minor sulfides, and rare earth minerals such as monazite, bastnäsite, parisite, and xenotime, with two mineralization stages including the early quartz-K-feldspar-calcite stage (Stage I) and the late sulfide-rare earth mineral-calcite stage (Stage II). The rare earth element contents of Stage I calcite are higher than those of the Stage II, especially heavy rare earth elements. Calcite from the different mineralization stages exhibits variable chondrite-normalized REE patterns, with the heavy rare earth elements and rare earth element abundances (134–1023 ppm) decreasing from the early to the late stage owing to the crystallization of xenotime. The δ¹³C (−5.39‰ to −6.68‰) and slightly higher δ¹⁸O (10.77‰ to 12.60‰) values for calcite from the Jialu carbonatites generally deviate from the values observed in the primary carbonatite field, which may be a result of Rayleigh-type fractionation. LA–ICP–MS U–Pb dating shows the lower-intercept ages of 243.8 ± 5 and 237.6 ± 1.3 Ma for the monazite and xenotime, respectively, with the weighted average ²⁰⁶Pb/²³⁸U ages of 240.9 ± 6 and 239.2 ± 1.3 Ma. These results indicate that the Jialu deposit was concurrent with Triassic carbonatite magmatism and rare earth element mineralization observed on the southern margin of the North China Craton. This implies that this region may have great rare earth element mineralization potential.

How to cite: Li, F., Zeng, Q., Fan, H., and Yang, K.: Unusual heavy rare earth elements enrichment and mineralization age in the Jialu deposit from the Qinling Orogen, central China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14613, https://doi.org/10.5194/egusphere-egu24-14613, 2024.

In the northernmost part of the Romanian Carpathians, the Maramureș region exposes several tectonic units comprising remnants of the Mesozoic Ceahlău - Severin Ocean. The “Black Flysch” unit contains a mafic complex extended in the Middle – Late Jurassic interval. These are covered by Upper Jurassic–Lower Cretaceous sediments, which include deep-water carbonates and siliciclastic deposits in the “Black Flysch” Nappe and mainly turbidites in the Ceahlău unit, which belong to the Outer Dacide nappe system.

The U-Pb age distribution spectra of detrital zircons obtained from the samples collected from the “Black Flysch” and Ceahlău tectonic units exhibit similarities within the range of 180–3,000 Ma. Significant peaks have been noticed at around ~460, 580–620, ~320, 180–200, and 950–1,100 Ma. Within the ‘Black Flysch’ Nappe prevail Ordovician ages (~460 Ma) associated with the Bucovinian Nappe basement. Conversely, in the Ceahlău Nappe, the Late Neoproterozoic peak (~600 Ma) holds greater significance, corresponding to the sediments of the Eastern European Platform and the paragneiss of the Bucovinian Nappe. The East European Craton contributes insignificantly as source area, given the minimal percentage of inherited ages surpassing 1 Ga.

How to cite: Lazar, C., Roban, R. D., and Ducea, M.: Provenance of the North Eastern Carpathian thrust sheet deposits based on geochronology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14745, https://doi.org/10.5194/egusphere-egu24-14745, 2024.

Chemical composition heterogeneity in carbonate rocks ranging from the microscale to several meters preclude their direct age determination. Therefore, stepwise dissolution of several bulk rock samples or subsamples of an individual specimen can provide information on the primary composition of the carbonate material and refine the resulting Pb–Pb age. A millimetre-thick carbonate-rich (white) and shale-rich (black) layer from the Rohtas Formation, Lower Vindhyan Group, was divided into eight subsamples each and subjected to three leaching steps. The first leachate (L1) was discarded, and subsequent leachates, L2 and L3, were obtained after 24 hours of leaching in 0.6M HBr. A Pb-Pb isochron age of 1666±25 Ma (n=23, MSWD=13) is obtained by regressing L2 and L3 leachates from both layers. Since initial leachates (e.g., L2) contain epigenetically altered carbonate material, data points in the ²⁰⁷Pb/²⁰⁴Pb vs ²⁰⁶Pb/²⁰⁴Pb plot are well correlated but show a large scatter. In contrast, regressing only the L3 leachates of both layers yielded a Pb-Pb isochron age of 1644±49 Ma (n=12, MSWD=7), with a reduced scatter and comparable with earlier published work. Increasing the number of leaching steps minimizes the degree of scatter and significantly improves the precision of the obtained Pb-Pb age. Two subsamples from phosphoritic stromatolite-bearing carbonate rocks of the Tirohan Dolomite from the Jankikund river section, Lower Vindhyan Group, were subjected to seven leaching steps, of one hour each, in 0.5M HBr. The Pb isotopic composition of the carbonate material dissolved in five steps (L3 to L7) was regressed to yield an isochron age of 1579±16 Ma (n=10, MSWD=1.3). The Pb-Pb age of the Tirohan Dolomite Member obtained by multi-step leaching in this study is indistinguishable within error from an earlier reported age ^[1] of 1650±89 Ma (n=5, MSWD=89), moreover shows a better correlation of the ²⁰⁷Pb/²⁰⁴Pb vs ²⁰⁶Pb/²⁰⁴Pb data. All the analyses were performed in static mode on a Thermo-Fisher Neptune Plus MC-ICPMS. The instrumental mass fractionation was corrected using both thallium-spiking and sample-standard bracketing. Furthermore, a generalized power law correction was applied to the ²⁰⁴Pb-corrected ratios of unknown samples using the ²⁰⁵Tl/²⁰³Tl ratios of the bracketing NBS-981 standards. The two-stage mass bias corrected ratios were then normalized by the ratios of NBS-981 during each analytical session. The long-term isotopic ratios of NBS-981 standard (n=71) are ²⁰⁶Pb/²⁰⁴Pb= 16.9371±0.0026 (2σ), ²⁰⁷Pb/²⁰⁴Pb= 15.4906±0.0046 (2σ), ²⁰⁸Pb/²⁰⁴Pb= 36.7042±0.0113 (2σ).

[1] Bengtson, S., Belivanova, V., Rasmussen, B., Whitehouse, M. (2009). The controversial “Cambrian” fossils of the Vindhyan are real but more than a billion years older. Proceedings of the National Academy of Sciences, 106(19), 7729-7734.

How to cite: Nandi, A., Vadlamani, R., and Bera, M. K.: Improving the precision of Pb-Pb ages of carbonate rocks by implementing stepwise dissolution techniques: A case study from the Lower Vindhyan Group, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14937, https://doi.org/10.5194/egusphere-egu24-14937, 2024.

Geochronological data on ore-bearing minerals can constrain the absolute ages and duration mineralising processes. Of the tungsten-bearing minerals, wolframite is the most promising geochronometer for these mineral systems, but high precision ages are hampered by common Pb and intra-grain heterogeneity. We present ID-TIMS and LA-ICP-MS U-Pb isotope data of wolframite , combined with milli scale (SEM-EDS) and microscale (LA-ICP-MS) element maps and nanoscale (FIB-TEM) chemical and structural images to elucidate the complex geochemical behaviour of this mineral and the implications for U-Pb geochronology.

During this study, three new U-Pb reference materials have been developed with ages of ca 158 Ma, 289 Ma and 325 Ma; these are available to interested laboratories. The best precision obtained by ID-TIMS was 1.24%, whilst we estimate the best possible precision for LA-ICP-MS ages to be ca 1.8%. Apart for analytical uncertainties, the main contributor to age uncertainty is the poor dispersion in U-Pb data (for Discordia fitting) and unknown common Pb composition for ID-TIMS data, and micron-scale heterogeneity for LA-ICP-MS data.

Microscale (LA-ICP-MS maps) to nanoscale (FIB-TEM) imaging techniques show large chemical and structural heterogeneity of wolframite related to the complex geological environments in which it is precipitated and altered. Trace element mapping highlights oscillatory and sector zoning not typically observed when using traditional SEM-based techniques. The variable distribution of the analysed elements (Fe, Mn, Sc, Nb, Ta, Y, Pb, Th and U for this study) can be explained both by coupled substitution and changing fluid chemistry recorded within a single wolframite crystal. The nano-scale structure of a strongly altered wolframite is characterised by rare ca 10x10 nm non-symmetric zones of amorphous crystal structure, and bands of elongate (ca 100 x 20 nm oval-shaped) low density zones that we consider representing porosity developed during rapid crystallisation of wolframite.

Although no real intra-grain age dispersion is observed in the analysed samples, the precision of U-Pb ages is strongly affected by the local chemical and structural characteristics of the wolframite. Most notably, the concentration of ²³⁸U and ²³⁸U/²⁰⁴Pb can vary by an order of magnitude within a zone smaller than a typically laser ablation spot (e.g., 100 µm).

How to cite: Carr, P., Romer, R., Chew, D., Wirth, R., and Mercadier, J.: Nano to milli scale characteristics of wolframite ([Fe,Mn]WO4)  and their implications for U-Pb geochronology of tungsten-bearing mineral deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14940, https://doi.org/10.5194/egusphere-egu24-14940, 2024.

A schist and a marble are used to investigate ⁴⁰Ar and Sr behaviour in white mica that show distinct records of deformation and fluid-mediated chemical exchange. The rocks were obtained from the upper level of the Middle Allochthon in the northern Scandinavian Caledonides. They underwent eclogite-facies metamorphism (2.4-2.6 GPa/590-660°C) at c. 486-481 Ma and were deformed during juxtaposition with the overlying Upper Allochthon in lower amphibolite/greenschist facies conditions at c. 430-420 Ma. Deformation of the schist is recorded by anastomosing shear bands that delimit polymineralic lenses of white mica, quartz, garnet, and apatite. White mica are only locally deformed along shear bands but show irregular zoning indicative of dissolution-reprecipitation, with high-celadonite zones (X_Cel: 0.22) generally enveloped by low-celadonite zones (X_Cel: 0.09). Fluid activity during rock deformation is evinced by the presence of chlorite in shear bands and surrounding partially retrogressed garnet, as well as dissolution-reprecipitation of plagioclase. Mobilization of trace elements is evident, with low-celadonite zones enriched in V, Sr, Nb, Ba and depleted in Li, Ti, Co, Zn relative to high-celadonite zones. The former also shows slight enrichment of average B (35.9 µg/g) compared to the latter (27.2 µg/g), but δ¹¹B values are the same for both zones (-13.5 and -13.6 ‰), suggesting locally-derived fluids. Deformation and foliation development of the marble is characterized by shape preferred orientation of calcite and white mica. The mica show variable grain size and are all deformed, highlighted by electron channeling contrast imaging that reveals abundant µm-scale kink bands within individual grains, a feature that is significantly less apparent in the schist mica. The marble mica show uniform high-celadonite content (X_Cel: 0.28), representing preservation of high-pressure mica chemistry during deformation. They show no trace element variations, except for a decrease B content with δ¹¹B values (36.3 µg/g and -18.1 ‰ to 15.5 µg/g and -22.0 ‰), which may be explained by heterogeneous devolatilization and preferential loss of ¹¹B during high-grade metamorphism. Thus, it is evident the mica remained closed to chemical exchange during deformation. The white mica ⁴⁰Ar/³⁹Ar dates from the schist are dispersed (491 ± 4 Ma to 427 ± 4 Ma), with the older dates typically provided by high-celadonite zones, and vice versa. The marble mica yielded a similar range of dates (486 ± 4 Ma to 428 ± 4 Ma), with finer-grains yielding younger dates. Weighted averages of single-spot Rb/Sr dates show a similar pattern for the schist (high-celadonite: 485 ± 8 Ma; low-celadonite: 427 ± 15 Ma). However, Rb/Sr dates from the marble mica only reproduce the older population of dates (481 ± 4 Ma) regardless of grain size. These results demonstrate that loss of ⁴⁰Ar from white mica can be facilitated by either fluid-mediated chemical exchange or deformation, but re-equilibration of Sr isotopes to reset Rb/Sr dates requires fluid-driven processes in lower amphibolite/upper greenschist facies conditions.

Research funded by NCN grant no. UMO-2021/40/C/ST10/00264 (C.J. Barnes), supported by “Juan de la Cierva” Fellowship JFJC2021-047505-I by MCIN/AEI/10.13039/501100011033 and CSIC (M. Bukała)

How to cite: Barnes, C., Zack, T., Gerdes, A., Dubosq, R., Camacho, A., Rösel, D., and Bukała, M.: Examining the behaviour of Sr and 40Ar in white mica in response to deformation and fluid-mediated chemical exchange, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15171, https://doi.org/10.5194/egusphere-egu24-15171, 2024.

Faults and related fractures have been studied for decades due to their potential in providing insights into past and present crustal deformation processes, climate evolution, seismology, and hydrology among others. Carbonates are very common syn-tectonic minerals that occur along fault planes or in fault-related fractures forming slickenfibres and veins (Roberts and Holdsworth, 2022). The ability of carbonates to incorporate uranium during their precipitation allows the application of in-situ carbonate U-Pb radioisotopic dating via LA-ICP-MS (Roberts et al., 2020). The integration of this method with the more conventional petrography and biostratigraphy holds strong potential in resolving the timing of brittle structure development. A robust pre-dating screening protocol using a multi-disciplinary approach, including structural, microstructural, petrographic, and isotopic characterization has been implemented to link carbonate precipitation event to fault kinematics.

This approach has been applied to the central Southern Alps (Northern Italy), where Early Jurassic rift-related faults are preserved despite their later involvement in the Alpine orogeny. Fieldwork and sampling focused on the Amora Fault (Bergamo, Italy), a rift-related N-S normal fault of the Jurassic Lombardian basin. Structural and paleostress analysis led to the identification of several mesoscopic N-S trending normal faults and veins both in the hanging wall and footwall of the Amora Fault, indicating an E-W extension. The fault is cross-cut by middle Eocene E-W trending magmatic bodies, which, in turn, are cross-cut by Alpine thrust faults. The Amora Fault and related minor faults also show strike-slip reactivation related to N-S Alpine compression.  

Sampling focused on the Norian to Lower Jurassic succession in the hangingwall and footwall of the main fault plane, where carbonate syn-tectonic veins and slickenfibres are present. Structural analysis allowed relating the structures to either the rifting or the Alpine reactivation.

Microstructural and petrographic analyses assisted by cathodoluminescence on 21 samples revealed the occurrence of several carbonate phases. Elemental analyses (Ca, Mg, Fe, Sr) and O-C stable isotope analyses confirmed the circulation of different fluids. U-Pb dating on the carbonate phases provided four age clusters, each connected to a tectonic phase: (1) Early to Middle Jurassic carbonates precipitated in rift-related structures from a fluid with a δ¹³C buffered by the host-rock. (2) Early Cretaceous carbonates possibly related to the late stage of rifting activity. (3) Late Cretaceous carbonates precipitated from a meteoric fluid during the early stages of the Alpine orogeny. (4) Oligo-Miocene carbonates connected to the strike-slip reactivation of rift-related normal faults.

The integration of field-based and stratigraphic observations with carbonate geochemistry and geochronology allowed the recognition of a complex reactivation history for the Amora Fault.

References

Roberts, N.M.W., Drost, K., Horstwood, M.S., Condon, D.J., Chew, D., Drake, H., Milodowski, A.E., McLean, N.M., Smye, A.J., Walker, R.J., and Haslam, R., 2020. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb carbonate geochronology: strategies, progress, and limitations. Geochronology 2, 33–61.

Roberts, N.M.W, and Holdsworth, R.E., 2022. Timescales of faulting through calcite geochronology: A review. Journal of Structural Geology, 158, 104578.

How to cite: Rocca, M., Zanchetta, S., Mangenot, X., Gasparrini, M., Berra, F., Deschamps, P., Guihou, A., and Zanchi, A.: Carbonate U-Pb geochronology as a tool to unravel complex fault evolution: an example from the central Southern Alps (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15293, https://doi.org/10.5194/egusphere-egu24-15293, 2024.

               Within the first five years of the initial introduction of multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) with the VG Elemental Plasma 54 the potential for the technique to be applied to Isotope Cosmochemistry applications had already been recognized¹. Early work focused on the ¹⁸²Hf-¹⁸²W chronometer, which had up until the introduction of MC-ICP-MS, been extremely difficult to measure with existing thermal ionization mass spectrometry (TIMS) techniques due to the extremely high first ionization potential of W.

In the following 25 years the use of MC-ICP-MS for Isotope Cosmochemistry applications has expanded to numerous other isotopic systems, including, but not limited to ²⁶Al-²⁶Mg, ¹⁴⁶Sm-¹⁴²Nd and ⁶⁰Fe-⁶⁰Ni, not just ¹⁸²Hf-¹⁸²W.  A general feature of these measurements is typically a reliance on excellent precision, on the order of a few ppm, 2RSD [2]. The high count rates required to achieve such excellent precision take time in order to achieve. Excellent precision over such time scales require a high performance mass spectrometer, capable of high sensitivity, stable throughout the course of the measurement and equipped with a low-noise detection array.

For over 20 years Thermo Fisher Scientific has pioneered developments in multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). The latest generation Thermo Scientific™ Neoma™ MC-ICP-MS, blends cutting-edge and field proven technology from the Ultra™ HR-IRMS and iCAP Qnova™ Series ICP-MS [3] and has the capability to complement and enhance Isotope Cosmochemistry applications [4]. Here we report our investigations into using the Neoma MC-ICP-MS and Neoma MS/MS MC-ICP-MS for a selection of Isotope Cosmochemistry application, including high precision Mg, Fe, Cu, Zn and W measurements.

[1] A. Halliday, D. Lee, J. Christensen, M. Rehkämper, W. Yi, X. Luo, C. Hall, C. Ballentine, T. Pettke, C. Stirling, Geochimica et Cosmochimica Acta, 1998, 62, 919-940.

[2] S. Goderis, R. Chakrabarti, V. Debaille, J. Kodolányi, 2016, J. Anal. At. Spectrom., 2016, 31, 841-862.

[3] Thermo Fisher Scientific, 2020, BR30600-EN 0520C: Neoma Multicollector ICP-MS [pdf], Thermo Fisher Scientific.

[4] Z. Deng, M. Schiller, M. G. Jackson, M-A. Millet, L. Pan, K. Nikoljsen, N. S. Saji, D. Huang, M. Bizzarro, Nature, 2023, 621, 100-104

How to cite: Craig, G., Pfeifer, M., Williams, N., Mournier, L., Bouman, C., and Lloyd, N.: High precision isotope ratio analysis for Cosmochemistry applications using the Thermo Scientific Neoma MC-ICP-MS., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15680, https://doi.org/10.5194/egusphere-egu24-15680, 2024.

U–Pb and U–Th geochronology of zircon in igneous rocks provides key information about the age, longevity, and assembly rates of magma reservoirs. Historically, the available analytical resolution limited these insights to an averaged “age” of a magmatic system. With dramatic improvements in analytical techniques over the last two decades, it has become possible to resolve extended records of zircon crystallisation within a single igneous sample, which can extend prior to its eruption or subsurface solidification by as much as a million years. In some magmatic systems these age spectra mirror those produced in zircon solubility models, reflecting monotonous cooling of a magma reservoir, whilst in others they may take other shapes indicative of a more complex interplay of processes [1,2]. Isolating the effect of these processes can be challenging since many analytical and geological factors also play a role. Such geological processes may include magma recharge or truncation of zircon crystallization by melt extraction.

In this study, we compiled high-precision zircon U-Pb dates from volcanic, plutonic and porphyry copper systems. We use the Wasserstein metric as a dissimilarity measure to compare distributions between all compiled age spectra. Dimensionality reduction of the resulting dissimilarity matrix reveals that plutonic systems have contrasting age spectra to volcanic and porphyry copper systems. Plutonic systems typically exhibit age spectra skewed towards older ages whereas volcanic and porphyry systems are skewed towards younger ages.

We adopt a bootstrap modelling approach to explain these differences, which allows the modelling of the effects of the number of sampled zircons, analytical uncertainties, magmatic recharge, mixed age domains and a truncation of crystallisation. The effects of multiple magmatic recharge events combined with truncation by volcanic eruption/dyke formation appear to be the most likely explanation for the young skew of volcanic and porphyry copper age spectra. Truncation of zircon crystallization alone appears to be incapable of explaining the full difference. Recognising the contrasting zircon age spectra between volcanic and plutonic systems is critical to improve eruption age estimation and interpretations of zircon compositions in petrological studies.

[1] Keller, C.B., et al., GPL, 2018. 31–35.

[2] Tavazzani, L., et al., EPSL, 2023. 623, 118432.

How to cite: Nathwani, C., Tavazzani, L., Szymanowski, D., Virmond, A., Markovic, S., and Chelle-Michou, C.: Controls on high precision zircon U-Pb age spectra in magmatic systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15969, https://doi.org/10.5194/egusphere-egu24-15969, 2024.

Geochronological methods play a pivotal role in unraveling the evolution of volcanic fields, providing insights into eruption timescales and recurrence. In the Quaternary Eifel volcanic field, with >300 maars and scoria cones, dating volcanic events remains challenging due to the scarcity of suitable materials for conventional dating methods. A promising approach to determine accurate eruption ages is to apply (U-Th)/He geochronology to zircon extracted from partially re-melted crustal xenoliths^1,2, which in case of Eifel maars are co-deposited with country-rock derived lithics and juvenile lapilli. However, the reproducibility of the method, if applied to xenoliths of different origin, age, composition, and texture, has not been studied for a single explosive eruption.

We collected >250 crustal xenoliths from >35 centers of the East and West Eifel volcanic fields. Coupled petrological investigation and zircon geochronology (U-Pb and U-Th) of a subset of these xenoliths reveal their diversity regarding protolith types (plutonic vs. low- to high-grade metamorphic), zircon crystallization ages (200 ka to 3 Ga) and degree of pyrometamorphic overprint (variable abundances of glass and vesicles, and crystal breakdown reaction textures). (U-Th)/He dating of the previously U-Th-Pb dated crystals (zircon-double-dating, ZDD) was performed to determine eruption ages for these centers.

Here, we focus on a xenolith suite (n = 8) from the Gemündener Maar and E-Schalkenmehrener Maar, two vents within a maar cluster known as Dauner Maar group. Tentative eruption ages of 20 to 30 ka were estimated from considerations on paleoclimate and crater morphology^3,4, and ESR xenolithic quartz dates of 30 ± 4 ka⁵. The pyroclastic deposits are rich in diverse zircon-bearing crustal xenoliths and thus, offer an ideal testbed to investigate how critical parameters such as xenolith rock type, zircon crystallization age, grain morphology, structure and chemical composition determined by Raman analysis and cathodoluminescence imaging, among others, could influence the measured (U-Th)/He ages. The investigated xenoliths comprise both magmatic and metamorphic protoliths with varying degree of pyrometamorphic overprint. Zircon U-Pb ages range from 115 ± 4 Ma to 2731 ± 66 Ma. Preliminary (U-Th)/He dates of individual xenoliths agree with the expected eruption age range, underscoring the feasibility of the method. A detailed analysis of parameters potentially affecting (U-Th)/He systematics in zircon ages is ongoing.

[1] Blondes, M.S., Reiners, P.W., Edwards, B.R., Biscontini, A., 2007, Dating young basalt eruptions by (U-Th)/He on xenolithic zircons: Geology, 35, 17–20.
[2] Ulusoy, İ., Sarıkaya, M.A., Schmitt, A.K., Şen, E., Danišík, M., Gümüş, E., 2019, Volcanic eruption eye-witnessed and recorded by prehistoric humans: Quat Sci Rev, 212, 187–198.
[3] Büchel, G., 1993, Maars of the Westeifel, Germany: Paleolimnology of European Maar Lakes, 49, 1–13.
[4] Lange, T., Cieslack, M., Lorenz, V., Büchel, G., 2022, Chronological sequence of volcanic eruptions in the SE part of the Westeifel Volcanic Field during the Weichselian Glaciation: Jber Mitt Oberrhein Geol Ver, 104, 313– 365.
[5] Woda, C., Mangini, A., A. Wagner, G., 2001, ESR dating of xenolithic quartz in volcanic rocks: Quat Sci Rev, 20, 993–998.

How to cite: Sturm, A., Schmitt, A. K., Danišík, M., and Dunkl, I.: Assessing the reproducibility of (U-Th)/He geochronology of xenolithic zircon: Insights from the Quaternary Eifel intraplate volcanic field, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16158, https://doi.org/10.5194/egusphere-egu24-16158, 2024.

Cassiterite (SnO₂) is one of the dominant ore phases in tin-tungsten bearing magmatic-hydrothermal deposits. It can contain high uranium contents and usually hosts low levels of common Pb, making it one of the best U-Pb geochronometers among ore minerals [1]. The widespread use of in-situ techniques to obtain crystallization ages for cassiterite, however, is limited by a paucity of accurately characterized reference materials (RMs). Such shortage is mostly caused by the difficulty of achieving closed-system acid decomposition of this mineral, which represents the foundation of isotope dilution techniques, necessary for accurate and precise determination of U-Pb isotopic composition using thermal ionization mass spectrometry (TIMS) techniques.

In this contribution, we present a new set of U-Pb isotopic compositions of two cassiterite samples from the archetypal Variscan Sn-W greisen deposits of Panasqueira (Portugal) and Krasno (Czechia) obtained with an updated protocol of complete HBr decomposition of cassiterite in the presence of a U-Pb tracer, followed by U and Pb purification, and TIMS analyses. Previous to dissolution, the U-Pb isotopic compositions of the same cassiterite aliquots are characterized via laser-ablation-inductively coupled-mass spectrometry (LA-ICP-MS) and each cassiterite fragment is imaged with an ultra-fast washout laser ablation system to obtain high-resolution maps of the content and distribution of key trace elements (e.g. U, Pb, Fe, REE).

These two samples show variable but high U concentrations (2-20 ppm) and produce U-Pb isochron ages with 1% precision and low dispersion. We compare these new materials with established RMs (Yankee [2]; AY-4 [3]) and discuss their usability as primary reference materials for microbeam applications.

[1] Neymark, L. A., et al., Chemical Geology. 2018, 483, 410-425.

[2] Carr, P.A., et al., Chemical Geology. 2020, 539, 119539.

[3] Yuan, S., et al., Ore Geology Reviews. 2011, 43, 235–242.

How to cite: Tavazzani, L., Szymanowski, D., Carr, P., Guillong, M., Buret, Y., Cortes-Calderon, E. A., Mercadier, J., and Chelle-Michou, C.: Two new cassiterite reference materials for in-situ U-Pb dating from the European Variscan metallogenic belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16536, https://doi.org/10.5194/egusphere-egu24-16536, 2024.

Recent years have seen a rise in applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to elemental and isotopic analysis of a wide range of geological materials, with a true explosion of in situ geochronology. Standardising such analyses relies on a homogeneous matrix-matched primary reference material (RM) whose ablation, transport and ionisation characteristics will result in fractionating elements and isotopes in the same way as in the unknown of interest.

One of the current frontiers of LA-ICP-MS geochronology – U–Pb dating of carbonates – suffers from a lack of such a material. Because the currently used primary RMs (e.g. WC-1 [1]) are heterogeneous in both age and U/Pb ratio, isotopic ratios are corrected on an isochron (whole-sample) basis rather than for each individual analytical spot, which imposes excess uncertainty on all U–Pb ages obtained this way. The U–Pb carbonate geochronology community is thus in urgent need of homogeneous reference materials for wide distribution. Ideally, such a RM should match the ablation behaviour of the unknown carbonate and consequently all matrix effects, including the amount and depth progression of inter-element laser induced elemental fractionation (LIEF), can be corrected directly, as is standard in e.g. zircon U–Pb geochronology.

We present a method for preparing synthetic RMs that uses a natural rock starting material which is milled to nano-powder, homogenised, and recrystallised using high-pressure, high-temperature apparatuses. In this way, natural sample heterogeneity is removed through milling, while textural coarsening is aimed at generating ablation behaviour similar to that of routine unknown samples.

Initial tests of synthetic calcite materials demonstrate the ability to achieve homogeneity at the spatial scale of a typical LA-ICP-MS laser spot size (80–110 µm typical for calcite U–Pb), while the ablation rate and LIEF are comparable to those of a range of commonly used calcite RMs. This suggests that experimental manufacturing of recrystallised carbonate is a promising avenue to obtain primary RMs that will allow spot-by-spot correction of LIEF in U–Pb analyses, thereby significantly reducing the reliance on heterogenous natural calcite RMs and improving the precision and accuracy of this analytical method.

Finally, this approach may serve as a blueprint for larger-scale production of primary RMs for a variety of matrices and isotopic systems for which there are no natural RMs characterised by the necessary homogeneity or availability.

[1] Roberts, N.M.W., et al., Geochemistry Geophysics Geosystems, 2017, 18(7): 2807-2814.

How to cite: Szymanowski, D., Kueter, N., Guillong, M., Tavazzani, L., and Akker, I. V.: Synthesising homogeneous carbonate reference materials for in situ U–Pb calcite geochronology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16896, https://doi.org/10.5194/egusphere-egu24-16896, 2024.

High-precision (CA-ID-TIMS) U-Pb geochronology of individual growth zones of zircon has been a long-awaited milestone in the geochronological community. Focused ion beam (FIB) and femtosecond (fs) laser machining monitored in real time by CL-SEM both show promise as techniques for physical extraction of target zircon domains in preparation for spatially resolved ID-TIMS dating. In this contribution, we test a novel laboratory protocol for zircon microsampling using an in-house multi-ion plasma (Ar-Xe) FIB and fs laser, and showcase first µID-TIMS zircon dates. We first examine the chemical impacts of protective metal coatings (Cr, Pt-Pd and C) used for ion milling on the U-Pb systematics of a low-Pb and a low-U zircon. We then present high-resolution transmission electron microscope (TEM) images of a zircon surface irradiated by ion and fs laser beams to show the contrasting extent of structural damage induced by the two techniques at standard microsampling conditions. Potential Pb-loss/U-gain in the nanometer-wide ion damaged layer in zircon is mapped by atom probe tomography (APT). Subsequently, we showcase the FIB workflow for extracting a number of microsamples of the Mud Tank and GZ-7 reference zircon spanning the sizes expected in future applications using natural zircon. We present first results of spatially resolved high resolution (µID-TIMS) dating of the Mud Tank and GZ-7 microsamples, and explore the achieved analytical accuracy and precision. Finally, we discuss the feasibility of conducting a µID-TIMS study on natural zircon given zircon features (i.e., age, U content, and volume of target domain) and research objective, and discuss benefits and limits to our approach.

How to cite: Markovic, S., Wotzlaw, J.-F., Szymanowski, D., and Chelle-Michou, C.: µID-TIMS: A Focused Ion Beam (FIB)–Femtosecond (Fs) Laser Microsampling Protocol for Spatially Resolved High-Precision Zircon Geochronology , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17149, https://doi.org/10.5194/egusphere-egu24-17149, 2024.

Elemental analyzers (EA) are the go-to sample introduction instrument for light stable isotope analyses of solid materials. Sample preparation is labor intensive and time consuming, with high associated consumable and equipment cost. Sample recovery is impossible in case of malfunctioning, i.e., no repeat analysis when sample amount is restricted.

In the same way, Laser ablation (LA) is traditionally considered a sample introduction technique for Inductively Coupled Plasma Mass Spectrometry (ICP MS) where plasma-based instrumentation will ionize and measure with a high degree of accuracy and precision the aerosol generated during the ablation process.

In this contribution we present an innovative method of measuring C stable isotopic ratios of carbonates by hyphening two instruments that are not usually found in the same lab. We coupled a laser ablation system (Teledyne Photon Machines Fusions CO2) equipped with a specially designed ablation chamber (Terra Analitic isoScell Δ100) to a Cavity Ring Down Spectrometer (Picarro G2201-i) to perform spatially resolved, highly accurate and precise measurements of both inorganic (stalagmite) and bioaccumulated (freshwater bivalve) carbonate samples. This novel system requires minimal sample preparation, allows for in-situ sequential and repeat sampling, all while eliminating the need to individually prepare samples.

How to cite: Stremtan, C., Wozniak, J., Puscas, C. M., and Tamas, T.: Laser Ablation – Cavity Ring Down Spectrometry, a new method for the in-situ analysis of δ13C of organic and inorganic carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17192, https://doi.org/10.5194/egusphere-egu24-17192, 2024.

Well-characterized matrix-matched reference materials are an indispensable requisite for mineral dating by LA-ICPMS. Recently, the in-situ U-Pb dating of low-U minerals (<20 µg/g) has emerged as a cutting-edge technique in the field of geochronology. The methodology has especially been applied to carbonate and garnet, although other minerals such as sulfate, ilmenite, staurolite, etc., are likely dateable by the same technique. However, the ability to expand this technique to such phases is hampered by the scarcity of reliable reference materials, creating a strong need for investigating and developing appropriate materials with well-constraint ages and homogeneous isotopic compositions.

During the last few years, the FIERCE laboratory has been investigating reference materials for garnet dating. Analysing garnet crystals from different localities and of various U and Pb contents, we found that four garnet localities have the potential to become reference materials for in-situ U-Pb studies. On the one hand, the availability of garnet crystals is sufficient to be distributed to laboratories worldwide. On the other hand, the garnet crystals analysed at FIERCE are relatively homogeneous, except for specific domains like rims, which showed slightly different ages (Millonig et al., 2023). The studied specimens come from Balochistan, with an approximate age of 45 Ma; Mongolia (ca. 130 Ma); Mali (black variety, different to the popular “Red-Mali”, age of ca. 200 Ma) and the Lake Jaco district in Mexico (pink variety, ca. 35 Ma). For this contribution, we have done an intra-crystal, inter-crystal and inter-session comparative study of the different localities, analysing multiple crystals from each locality over multiple analytical sessions. The potential reference materials analyses have been cross-calibrated against garnet crystals of known age (ID-TIMS age) and yield reproducible ages between different analytical sessions. Furthermore, garnet from the four localities will also be analysed by TIMS to provide independent age constraints.

How to cite: Beranoaguirre, A., Millonig, L. J., Stifeeva, M. V., Albert, R., Marschall, H., and Gerdes, A.: Potential matrix-matched reference material for in-situ garnet U-Pb dating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18378, https://doi.org/10.5194/egusphere-egu24-18378, 2024.

Understanding the stability of carbonates under high pressure and temperature is essential for modelling the carbon balance and cycle in the deep Earth. In the presence of an H₂O-containing fluid, the melting curve of carbonates can be strongly reduced to a lower temperature. Since magnesite is an important carbonate host in the Earth's mantle, the melting curve of magnesite in the presence of an H₂O-containing fluid is of particular interest.

Here we report results from in situ synchrotron energy dispersive X-ray diffraction experiments and use texture observations from ex situ falling sphere experiments in the brucite-magnesite system between 1 and 12 GPa. We define the dehydration and melting curve of brucite and elucidate the stability of magnesite in the presence of a liquid and periclase.

The observed liquidus provides information on the fate of magnesite-bearing rocks in subduction zones. Our results show that magnesite remains stable under typical subduction zone gradients even when infiltrated by hydrous fluids released by dehydration reactions during subduction. We conclude that magnesite can be subducted to depths below the arc and beyond. Our results therefore have important implications for the carbon budget of the Earth's mantle and its role in the regulation of the carbon cycle.

How to cite: Sieber, M. J., Reichmann, H. J., Farla, R., and Koch-Müller, M.: Stability of magnesite (MgCO3) in the presence of a hydrous fluid in the upper mantle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18595, https://doi.org/10.5194/egusphere-egu24-18595, 2024.

Continental breakup leads to formation of new oceanic gateways, evolution of ocean bathymetry, and, in many cases, emplacement of large igneous provinces (LIPs). Changes in ocean circulation, volcanic CO₂ emissions, and alteration of freshly emplaced ocean crust associated with these events were likely drivers of global-scale Cretaceous climate change. Yet, the precise timing and nature of Cretaceous continental rifting and submarine LIP eruptions remain largely unconstrained. The Agulhas Plateau (AP), along with Maud Rise (MR) and Northeast Georgia Rise (NEGR), are thought to constitute a once contiguous submarine LIP that was emplaced in the gateway between the incipient South Atlantic, Southern Ocean, and Indian Ocean basins during the breakup of Africa and East Antarctica. International Ocean Discovery Program (IODP) Expedition 392 recovered sedimentary and igneous rocks from the Agulhas Plateau, southwest Indian Ocean, including basaltic pillow lavas at IODP Site U1582, located on the northernmost edge of the plateau. Calcite veins and infills hosted in pillow lavas can provide insights into the timing and chemical environment of post-magmatic fracturing, fluid circulation, submarine weathering and carbonation of the LIP. We present in-situ U/Pb ages (n=12) of the calcite veins determined via laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), clumped isotope (Δ₄₇) compositions (n=6) and ⁸⁷Sr/⁸⁶Sr ratios to investigate the timing and temperature of calcite precipitation. U/Pb geochronologic dates for vein calcite and infill are reproducible and yield Cenomanian to Turonian ages, consistent with shipboard nannofossil biostratigraphic age constraints for sediments intercalated between the pillows. Reproducible clumped isotopic paleotemperatures range from ~19 to 26°C, with a calculated δ¹⁸O value for precipitating fluids of ~-2 to +1‰ Vienna Standard Mean Ocean Water (VSMOW). The ranges of both these values are consistent with ambient mid-Cretaceous marine waters and, when combined with the age constraints for the basalt and sediments, support rapid weathering and carbonation of the submarine LIP following post-eruptive cooling. U/Pb geochronology of calcites at IODP Site U1582, refined by Sr isotope stratigraphy, provide a minimum age for the Agulhas Plateau. These data constrain the timing of the formation of a paleobathymetric restriction at the gateway between several incipient Cretaceous ocean basins, and have implications for geochemical interactions between mafic igneous rocks and seawater through the life cycle of a Cretaceous LIP.

How to cite: Gürer, D., Jones, M. M., Bohaty, S. M., Bernasconi, S. M., Nana Yobo, L., and Roberts, A. P.: Agulhas Plateau large igneous province emplacement and carbonation constrained by in-situ U-Pb dating, Sr isotope geochemistry and clumped isotope thermometry of calcite veins in basaltic basement at IODP Site U1582, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19239, https://doi.org/10.5194/egusphere-egu24-19239, 2024.

Understanding fluid processes is crucial for understanding the magmatic and metamorphic evolution of rocks, as well as mineral transport and deposition. Targeted in situ geochronology of minerals which have interacted with fluids allow us to investigate the temporal evolution of these fluid systems. Combined with trace element analysis or stable isotope analysis it is possible to gain insight into the nature of source of mineralising fluids. These results contribute to modelling and understanding of mineral systems which can be used for targeting mineral deposits.

Early results of this work are presented based on situ Lu-Hf geochronology applied to garnet and apatite associated with a variety of mineral deposits from Finland. The mineral deposits are hosted in rocks are variable age (Archean to Proterozoic) and all were affected by the Svecofennian orogeny (1.92-1.78 Ga) causing deformation, metamorphism and/or remobilisation.

The Siilinjärvi P deposit hosted in a 2.61 Ga carbonatite (Karhu et al., 2001) presents apatite ages ranging from 2050 to 2260 Ma and calcite ages of 1800 to 1920 Ma indicating potentially several phases of fluid remobilisation which may be prior to or during the Svecofennian orogeny.

The Kiviniemi Sc deposit is hosted in a garnet bearing ferrodiorite (1857 ± 2 Ma, U-Pb zircon; Halkoaho et al 2020). In situ Lu-Hf analysis of garnet produces an age of 1824 ± 18 Ma and for apatite an age of 1835 ± 19 Ma.

Garnet and apatite geochronology has also been applied to Li bearing pegmatites in the Somera-Tammela pegmatite province in Southern Finland. Garnet gave an age of 1801 ± 53 Ma and apatite gives 1835 ± 26 Ma. A second sample produced a nearly identical apatite age of 1835 ± 15 Ma.

Two garnets were sampled from inferred Archean deposits, the Sotkamo silver Mine is hosted in the Tipasjärvi Greenstone Belt and the Hosko gold deposit hosted in the Ilomantsi Greenstone Belt. In Sotkamo garnet from a quartz vein hosting base metal mineralisation produced a Lu-Hf age of 1870 ± 27 Ma. Two garnet samples were dated from the Hosko gold deposit, in mineralised sediments, garnet associated with vein quartz produced an age of 1837 ± 4 Ma. A granitic vein cross-cutting the ore hosting sediments gave an age of 2620 ± 7 Ma, although this sample clearly recorded a resetting event with younger ages obtained from the rim.

Despite only have the age results so far, it is clear that the Svecofennian orogeny had a strong impact on mineral systems, reworking of deposits thought to be Archean.

Halkoaho, T., Ahven, M., Rämö, O.T., Hokka, J., Huhma, H., 2020, https://doi.org/10.1007/s00126-020-00952-2

Karhu, J.A., Mänttäri, I., Huhma, H., 2001. Radiometric ages and isotope systematic of some Finnish carbonatites. University Oulu, Res. Terrea, Ser. A. No. 19.8.

How to cite: Cutts, K., Szentpeteri, K., Karvinen, S., Glorie, S., Käpyaho, A., and O'Brien, H.: In situ Lu-Hf dating of garnet and apatite as a means to understand fluid processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19715, https://doi.org/10.5194/egusphere-egu24-19715, 2024.

The Tabei uplift is located in the northern part of the Tarim Basin, while the Lunan area is in the eastern part of Tabei uplift. The dryness coefficients of natural gas range from 0.62 to 0.99 (average: 0.92), the methane contents range from 30.42% to 96.4% (average: 85.10%), and the methane carbon isotopes range from -47.30‰ to -33.80‰ (average: -36.96‰) in the Lunnan area. Compared with the actual regional thermal evolution of the source rock, the natural gas exhibits excessively heavy dryness coefficients and methane carbon isotope characteristics. To investigate the genesis of heavy methane carbon isotopes and dry gas in different areas of the Tabei Uplift. Natural gas chemical composition and carbon isotope were used to analyze the genesis of natural gas, basin modeling was conducted to reconstruct the natural gas generation process, and the geologic causes of this phenomenon are discussed. The results show that the natural gas is primary cracking gas and sourced from marine type II kerogen. The dryness coefficient, methane carbon isotopes, and source rock maturity gradually increases from the west to the east. Instantaneous effects led to the dry gas and relative heavy methane carbon isotopes generated at a low maturity level. The current natural gas in the Ordovician reservoirs was all generated during the Himalayan orogeny. Long period pause of the gas generation between the two hydrocarbon generation phases is the main cause for the instantaneous effects.

How to cite: Liu, X., Tian, J., Liu, Z., and Cong, F.: The generation mechanism of deep natural gas, Tabei uplift, Tarim Basin, Northwest China: insights from instantaneous and accumulative effects, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2342, https://doi.org/10.5194/egusphere-egu24-2342, 2024.

Serpentinite carbonation contributes to the deep carbon (C) cycle. Recently, geophysical and numerical studies have identified considerable hydrothermal alterations in deep bending faults beneath outer-rise regions, implying potentially significant C storage in the slab mantle. However, quantitative determination of C uptake in outer-rise regions is lacking. Here, we experimentally constrained the serpentinite carbonation in H₂O–CO₂–NaCl fluids under bending fault conditions to estimate C uptake in the slab mantle. We found that serpentinite carbonation produced talc and magnesite along the serpentinite surface. The porous reaction zones (49.2% porosity) promoted the progress of the carbonation reaction through a continuous supply of CO₂-bearing fluids to the reaction front. Strikingly, NaCl effectively decreased the serpentinite carbonation efficiency, particularly at low salinities (< 5.0 wt%), which is likely attributed to the reduction in H₂O and CO₂ activities (a_H2O and a_CO2) and transport rate of reactants, the change in pH of fluids, and the enhancement of magnesite solubility. We fitted an empirical equation for the reaction rate of serpentinite carbonation in bending faults and found that this reaction could contribute to a flux of 25–100 Mt C/yr in subduction zones. Our results shed new light on the deep C cycle and the serpentinite carbonation in environments with high salinities.

How to cite: Huang, Y., Okumura, S., Matsumoto, K., Takahashi, N., Tang, H., Wu, G., Tsujimor, T., Nakamura, M., Okamoto, A., and Li, Y.: Importance of mantle serpentinite carbonation in bending faults for the deep carbon cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5003, https://doi.org/10.5194/egusphere-egu24-5003, 2024.

Coupled dissolution-precipitation reactions have been studied extensively recently for their ability to retain elements of interest into a stable solid form that can sequester potentially toxic elements. This is achieved through the initial dissolution of a substrate mineral in a fluid containing the target (often toxic) element. The dissolution leads to the supersaturation of a boundary layer at the mineral surface with respect to another solid phase containing the element of interest¹. When the relative solubilities of the different minerals (in the aqueous fluid at the reaction interface) and their molar volume difference allow it, a coupled dissolution-precipitation can lead to the pseudomorphic replacement of the original substrate². We tested this reaction for CaCO₃ and cadmium (Cd) containing solutions as calcite (CaCO₃) and otavite (CdCO₃) form an almost perfect solid solution. We compared the reaction in similar solutions with different types of CaCO₃: calcite single crystal, Carrara marble (polycrystalline calcite) and aragonite single crystals. For single calcite crystals, the reaction in a Cd-solution passivates the crystal’s surface due to the epitaxial growth of a (Ca,Cd)CO₃ solid solution layer of low solubility. However, the random orientation of the grains in the Carrara marble samples and the change of crystal structure for the aragonite crystals modified the mechanism and allow the replacement of CaCO₃ by (Ca,Cd)CO₃ to take place³. Hydrothermal experiments and in situ fluid-cell atomic force microscopy (AFM) were used to observe the reaction both at room temperature and high pressure and temperature (200°C). In addition to SEM, BSE and EDX observations, synchrotron X-ray microtomography images were acquired on Carrara marble and aragonite samples at different stages of the reaction in order to gather more information about the replacement mechanism and the extent of Cd-uptake achievable through this process. The extent of the reaction was shown to be similar for the different solution concentrations used and limited in the case of Carrara marble. The porosity closes fast after the start of the reaction blocking the fluid pathways necessary for the reaction to proceed. The reaction in the aragonite samples seems to progress mainly through a reaction-induced fracture network probably created by the stress caused by the crystallographic structural differences between parent and product phases. Overall, these results demonstrate the capacity of CaCO₃ to trap and store cadmium into a solid phase by a mechanism of coupled dissolution-precipitation.

(1)        Putnis, C. V.; Putnis, A. A Mechanism of Ion Exchange by Interface-Coupled Dissolution-Precipitation in the Presence of an Aqueous Fluid. Journal of Crystal Growth 2022, 600, 126840. https://doi.org/10.1016/j.jcrysgro.2022.126840.

(2)        Pollok, K.; Putnis, C. V.; Putnis, A. Mineral Replacement Reactions in Solid Solution-Aqueous Solution Systems: Volume Changes, Reactions Paths and End-Points Using the Example of Model Salt Systems. American Journal of Science 2011, 311 (3), 211–236. https://doi.org/10.2475/03.2011.02.

(3)        Julia, M.; Putnis, C. V.; King, H. E.; Renard, F. Coupled Dissolution-Precipitation and Growth Processes on Calcite, Aragonite, and Carrara Marble Exposed to Cadmium-Rich Aqueous Solutions. Chemical Geology 2023, 621, 121364. https://doi.org/10.1016/j.chemgeo.2023.121364.

How to cite: Julia, M., Putnis, C. V., Renard, F., and Plümper, O.: Potential sequestration of toxic elements: the specific example of cadmium and carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5717, https://doi.org/10.5194/egusphere-egu24-5717, 2024.