GMPV1.3 | Carbonate geochronology, trace element and stable isotope geochemistry — applications and advances
EDI
Carbonate geochronology, trace element and stable isotope geochemistry — applications and advances
Co-organized by BG2/GI5/SSP3/TS9
Convener: Johannes Rembe | Co-conveners: Aileen Doran, Philip Rieger, Goran Andjic, Renjie Zhou
Orals
| Tue, 25 Apr, 08:30–10:15 (CEST)
 
Room -2.47/48
Posters on site
| Attendance Tue, 25 Apr, 16:15–18:00 (CEST)
 
Hall X2
Posters virtual
| Attendance Tue, 25 Apr, 16:15–18:00 (CEST)
 
vHall GMPV/G/GD/SM
Orals |
Tue, 08:30
Tue, 16:15
Tue, 16:15
Carbonate minerals are ubiquitous throughout all geological environments in the Earth`s crust, forming via biogenic, marine, diagenetic, hydrothermal, magmatic, and metamorphic processes. Therefore, refining our understanding of carbonate formation can contribute towards addressing important geological and societal problems, such as the Earth`s past and present carbon cycle or the exploration of critical raw materials. The study of carbonate minerals is one that crosses multiple sectors and disciplines, with several novel applications emerging in recent years. Similarly, recent analytical developments allow for the application of geochronological, trace element and isotope geochemical techniques across a wide range of scales and sample materials. To keep track of these emerging techniques, this session aims to bring together an interdisciplinary community working both on method development and on the application of techniques investigating carbonate minerals. We invite geoscientists from all fields (e.g., paleoceanology, economic geology, igneous petrology, carbon storage) to contribute to this session by presenting their research in carbonate geochronology (e.g., U-Pb dating), carbonate trace element geochemistry (e.g., rare earth elements), and carbonate isotope geochemistry (e.g., strontium, clumped isotopes).

Orals: Tue, 25 Apr | Room -2.47/48

Chairpersons: Johannes Rembe, Aileen Doran
08:30–08:35
08:35–08:45
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EGU23-15974
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ECS
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solicited
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Highlight
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Virtual presentation
Shitou Wu, Nick Roberts, and Zhongwu Lan

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb geochronology for carbonate minerals, calcite in particular, is rapidly gaining popularity as an absolute dating method. In this study, we review the latest technical progress in LA-ICP-MS carbonate geochronology, including the pre-screening strategies (on-line spot selection with a threshold, image-guided approach, and image-based approach), preferred instrumentation (Q-ICP-MS, SF-ICP-MS and MC-ICP-MS), calibration methods, common Pb corrections and the development of reference materials, with the aim of further improving the precision and accuracy of this technique. We emphasized the characterization of two calcite reference materials (TLM and LSJ07) for micro-beam U-Pb geochronology and C, O isotope ratio measurements. The latest geological applications of LA-ICP-MS U-Pb carbonate geochronology in dating of diagenesis and hydrothermal activity were reviewed.

How to cite: Wu, S., Roberts, N., and Lan, Z.: LA-ICP-MS U-Pb carbonate geochronology and its geological applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15974, https://doi.org/10.5194/egusphere-egu23-15974, 2023.

08:45–08:55
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EGU23-123
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Highlight
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On-site presentation
Chuuan-Chou (River) Shen, Felicia Beardsley, Shou-Yeh Gong, Osamu Kataoka, Minoru Yoneda, Yusuke Yokoyama, Leilei Jiang, Albert Yu-Min Lin, James Fox, Jason Barnabas, Gus Kohler, Zoe T. Richards, and Jean-Paul A. Hobbs

Great Holocene civilizations on Pacific islands were created by Homo sapiens. However, most of the construction histories remain uncertain due to the lack of developed writing system and the limitation of dating techniques. Nan Madol (0.7 km in width and 1.5 km in length), an abandoned city called the “Venice of the Pacific” with over 100 artificial islets, is located on the southeastern coast of island Pohnpei in Micronesia. This world-unique ruin, inscribed onto UNESCO’s World Heritage List in 2016, was built with basalt megaliths and scleractinian coral cobbles. Oral histories and previous charcoal 14C ages suggested that the main construction of Nan Madol of Pohnpei could begin in the 13th or 14th century and ceased at the 16th or 17th century, associated with the rise and fall of the Saudeleur Dynasty. However, after 150 years or more of studies, the timing of construction and the dynasty, and the probable influence of environmental factors, remain unresolved. High-precision U-Th dating techniques, developed at the High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, were used to date the selected pristine coral infills and reveal the construction time of the two ruins. With over 150 coral ages determined, results show a peak of construction activity during the middle 11th century could be related to the rise of the Saudeleur Dynasty. In the early 15th century, construction activities ceased, associated with the dynasty’s downfall. Our study shows that Nan Madol construction and the rise and fall of the dynasty occurred 2-3 centuries earlier than previously estimated. Moreover, the entire development was dominated by El Niño-Southern Oscillation variability and tectonic-related sea level rise.

How to cite: Shen, C.-C. (., Beardsley, F., Gong, S.-Y., Kataoka, O., Yoneda, M., Yokoyama, Y., Jiang, L., Lin, A. Y.-M., Fox, J., Barnabas, J., Kohler, G., Richards, Z. T., and Hobbs, J.-P. A.: Dating a world-unique Pacific ruin: Nan Madol, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-123, https://doi.org/10.5194/egusphere-egu23-123, 2023.

08:55–09:05
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EGU23-265
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On-site presentation
Riccardo Lanari, Anda Buzenchi, Alessandro Bragagni, Bruno Dhuime, Mauro Brilli, Chiara Del Ventisette, Massimo Mattei, Sandro Conticelli, and Riccardo Avanzinelli

The application of U-Pb dating method performed on calcite has exponentially increased over the last years, since constraining the age of the crystallization for such syn-kinematic minerals, would provide a specific timing of faults movement. The potential gain of this approach is evident but the robustness of the U-Pb method performed on calcites has been not yet systematically tested.  Here, we firstly demonstrated that a mineral/fluid interaction indeed affects the regression of the 238U/206Pb and 207Pb/206Pb data-points and therefore the age; and secondly, we propose an innovative application of U-Pb dating method and a new strategy to identify and reject analytically robust isochrons.

We explore 36 samples, combining U-Pb dating performed with different methods along with carbon and oxygen stable isotopes compositions measured on the same fibres of calcite. The extremely high precision 207Pb/206Pb measured by Thermal Ionisation Mass Spectrometry  revealed that every sample experienced a certain degree of fluid interaction. We find no correlation between 238U/206Pb and the spread in δ18O. The higher spread in δ18O is instead coupled with a remarkable scattered data-points that yield U-Pb ages calculated with the different methods on the same samples with a large variability. In conclusion, our study demonstrates that great care must be taken when considering radiometric ages made on calcite since LA-ICP-MS large uncertainties might obscure the isotopic reorganization.

How to cite: Lanari, R., Buzenchi, A., Bragagni, A., Dhuime, B., Brilli, M., Del Ventisette, C., Mattei, M., Conticelli, S., and Avanzinelli, R.: Mineral/Fluid interaction as a potential bias in calcite U-Pb dating, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-265, https://doi.org/10.5194/egusphere-egu23-265, 2023.

09:05–09:15
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EGU23-4234
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Virtual presentation
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Zhongwu Lan, Nick M W Roberts, Shitou Wu, Fangyue Wang, Hao Wang, Rong Cao, Zhensheng Li, Ying Zhou, Kaibo Shi, and Bo Liu

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb geochronology of calcite has been an emerging research direction in recent years that has been widely applied to various disciplines, such as dating of brittle deformation, biological biomineralization, oceanic crust alteration, and hydrocarbon migration. The method has the advantage of quickly locating regions of relatively high uranium content and radiogenic lead that avoids the time-consuming procedures traditionally required for isotope dilution methods. Herein, we show how this method is successfully applied to dating of diagenesis and hydrothermal activity in Precambrian-Phanerozoic sedimentary rocks, but with a note of caution that the susceptibility of the calcite U-Pb isotope system to fluid activities means interpretation of calcite U-Pb data and selection of calcite standard should be cautioned. We demonstrate the following case studies: LA-ICP-MS calcite U-Pb geochronology has aided in defining the Mesoproterozoic-Neoproterozoic boundary (ca. 1010 Ma) in North China Craton. It also constrains the timing of calcite infillings in the Ediacaran cap carbonate to be ca. 636 Ma, indicating an early diagenetic origin and thus confirming a methane seepage hypothesis. Two episodes of hydrothermal activity (ca. 290 Ma and ca. 250 Ma) have been recognized from the Cambrian carbonate in the Tarim region, which was induced by the Permian Tarim Large Igneous Province (LIP) and Indosinian orogeny, respectively.

How to cite: Lan, Z., M W Roberts, N., Wu, S., Wang, F., Wang, H., Cao, R., Li, Z., Zhou, Y., Shi, K., and Liu, B.: Application of carbonate U-Pb geochronology in dating of diagenesis and hydrothermal activity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4234, https://doi.org/10.5194/egusphere-egu23-4234, 2023.

09:15–09:25
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EGU23-13236
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On-site presentation
Catherine Mottram, Dawn Kellett, Paul Dennis, and Matthieu Clog

Carbonate veins are ubiquitous in many ore deposits and are often interpreted as a late stage or cross cutting fluid flow events in the ore deposit history. Faults accommodate rock displacement and the resulting zones of weakness act as conduits for magma and localised magmatic-hydrothermal fluid flow, leading to the formation of ore deposits. Dating of both low temperature veins and brittle fault material has been notoriously difficult because of a lack of ‘datable’ material. Using innovative techniques, it is now possible to date carbonate with the U-Pb isotopic system.

Here we use in-situ U-Pb carbonate geochronology to date a variety of fault material and mineralised and unmineralised veins within a major fault-controlled Cu-Au-Mo porphyry system in the central Yukon, Canadian Cordillera. Over 50 samples have been dated, revealing a long history of faulting and fluid flow in the deposit spreading over 10s of millions of years between ~75 Ma and <20 Ma. We combine petrography, U-Pb carbonate geochronology, trace element geochemistry, and clumped isotope analysis to interpret the full temperature-time evolution of the fluids within the deposit. Our results show the carbonate veins crystallised during the main ore-forming event at ~75 Ma. Subsequently, there was a prolonged period of fault-controlled fluid pulsing that likely concentrated metallic minerals in the deposit. The findings show that carbonate veins are not always late features within ore deposits and are an underutilised resource for understanding the full temporal and fluid evolution of a system. Carbonate U-Pb geochronology is therefore potentially incredibly useful for telling the previously untold and long history of fluid flow in a variety of deposit types.

How to cite: Mottram, C., Kellett, D., Dennis, P., and Clog, M.: Longevity of fault-controlled fluid flow within a Cu-Au-Mo porphyry (Yukon, Canada) revealed by coupled U-Pb carbonate geochronology and clumped isotope analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13236, https://doi.org/10.5194/egusphere-egu23-13236, 2023.

09:25–09:35
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EGU23-7797
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ECS
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On-site presentation
Melanie J. Sieber, HansJosef Reichmann, Robert Farla, Oona Appelt, Marcus Oelze, Christian Lathe, and Monika Koch-Müller

The presence of magnesite (MgCO3) in the Earth’s mantle plays a fundamental role in reducing the melting point of the mantle [1] and forming carbonate‑rich melts such as kimberlites and carbonatites [2]. The melting curve of (dry) magnesite is well constrained [3, 4], but melting of magnesite in the presence of H2O, providing the basis for more complex (natural) systems, is poorly understood from some quenched experiments [5]. Also, the distribution of trace elements such as Li, Sr, Pb, and rare earth elements during melting of magnesite is poorly considered in models that evaluate the trace element budget of carbonate‑rich melts parental to kimberlites [6].

Here we report, first, the H2O‑present melting curve of magnesite between 2 and 12 GPa. The melting curve of magnesite mixed with 16 wt% brucite was established by in ‑ situ X‑ray diffraction measurements using the large volume press at P61B at PETRA III (DESY). Second, we report trace element partitioning data for congruent melting of calcite and incongruent melting of magnesite producing carbonate melt and periclase between 6 and 9 GPa. Those results were obtained from quenched experiments using a rocking multi‑anvil press at the GFZ overcoming equilibrium and quenching problems in previous studies [7].

 

1          Dasgupta and Hirschmann, The deep carbon cycle and melting in Earth's interior. Earth and Planetary Science Letters, 2010. 298(1-2): p. 1-13.

2          Jones, Genge, and Carmody, Carbonate Melts and Carbonatites. Reviews in Mineralogy and Geochemistry, 2013. 75(1): p. 289-322.

3          Solopova, Dubrovinsky, Spivak, Litvin, and Dubrovinskaia, Melting and decomposition of MgCO3 at pressures up to 84 GPa. Physics and Chemistry of Minerals, 2014. 42(1): p. 73-81.

4          Müller, Koch-Müller, Rhede, Wilke, and Wirth, Melting relations in the system CaCO3-MgCO3 at 6 GPa. American Mineralogist, 2017. 102(12): p. 2440-2449.

5          Ellis and Wyllie, Carbonation, hydration, and melting relations in the system MgO-H2O-CO2 at pressures up to 100 kbar. American Mineralogist, 1979. 64(1-2): p. 32-40.

6          Girnis, Bulatov, Brey, Gerdes, and Höfer, Trace element partitioning between mantle minerals and silico-carbonate melts at 6–12GPa and applications to mantle metasomatism and kimberlite genesis. Lithos, 2013. 160-161: p. 183-200.

7          Buob, Experiments on CaCO3-MgCO3 solid solutions at high pressure and temperature. American Mineralogist, 2006. 91(2-3): p. 435-440.

How to cite: Sieber, M. J., Reichmann, H., Farla, R., Appelt, O., Oelze, M., Lathe, C., and Koch-Müller, M.: H2O-present melting curve of magnesite and trace element distribution during melting of (dry) magnesite and calcite in the upper mantle, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7797, https://doi.org/10.5194/egusphere-egu23-7797, 2023.

09:35–09:45
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EGU23-4758
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ECS
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On-site presentation
Dong Shao, Yigui Han, Meng Li, Lihui Lu, Xuyang Cao, and Pengcheng Ju

The global-scale glacial events recorded by diamictite and cap carbonate couplets occurred in the late Neoproterozoic and has been recognized on at least 15 paleo-continents. Diamictite and cap carbonate couplets play a pivotal role in establishing regional stratigraphic correlations and understanding the extreme climatic conditions and glacial-interglacial cycles of the Neoproterozoic glaciation. Here we report newly discovered Neoproterozoic glaciogenic diamictite and cap carbonate couplet in the Longshoushan area at the southwestern margin of the Alxa Block, NW China. Based on detailed stratigraphic and sedimentologic studies, we identified massive and stratified diamictites at the bottom of the Hanmushan Group, both with poorly sorted and rounded gravels. The presence of glacial striations and ice-rafted dropstones in stratified diamictites supports a glaciogenic origin. The upward transition from massive diamictites to stratified diamictites indicates the process of glacier retreat. The occurrence of thin-bedded phyllites in the stratified diamictites suggests a short-term deglaciation during the glaciation. The 2- to 2.6-m-thick cap carbonates cover the stratified diamictites and consist of thinly laminated microcrystalline dolomites. The basal cap carbonates contain closely linked sheet cracks, cemented breccias, tepee-like structures and cavities. The cap carbonates show high-resolution 13CPDB chemostratigraphy and negative δ13C values (ca. −2.9 to −4.1‰), typical of the Marinoan cap carbonates. Regional sedimentary characteristics and the C-O isotope values suggest that the diamictites and cap carbonate couplet in the Alxa Block likely correspond to the Marinoan glaciation and subsequent deglaciation (ca. 635 Ma), not the previously assumed Ediacaran glaciation. Thus, the diamictite and cap carbonate sequence marks the Cryogenian-Ediacaran boundary in the Alxa Block and provides evidence for further stratigraphic correlation and investigation. This work was financially supported by NSFC projects (grants 42072264, 41730213, 41902229, 41972237) and Hong Kong RGC GRF (17307918).

How to cite: Shao, D., Han, Y., Li, M., Lu, L., Cao, X., and Ju, P.: Discovery of Neoproterozoic glaciogenic diamictites and cap carbonate couplet in the Alxa Block, NW China: Evidence from stratigraphic, sedimentologic and geochemical studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4758, https://doi.org/10.5194/egusphere-egu23-4758, 2023.

09:45–09:55
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EGU23-9499
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On-site presentation
David Nelson, Scott Herndon, Zhennan Wang, Jay Quade, and David Dettman

Isotopic analysis using high resolution Isotope Ratio Laser Spectroscopy (IRLS) has been shown to be advantageous to multiple geochemical applications during the last decade.  These advances include isotopic analysis of the bulk isotopic compositions of water, carbon dioxide, methane and nitrous oxide.  More recently, laser spectroscopy has been used by several groups to examine the isotopic compositions of methane, carbon dioxide and nitrous oxide when carrying two rare isotopes (so called clumped isotopes).   Our recent work using Tunable Infrared Laser Direct Absorption Spectroscopy (TILDAS) has demonstrated highly accurate (~0.01 ‰) measurements of the clumped (16O13C18O or 638 in HITRAN isotope notation) isotopic composition of carbon dioxide derived from carbonate samples with spectroscopic measurement times of ~30 minutes using a dual laser spectrometer.  That spectrometer is optimized for the measurement of the four isotopologues required to calculate Δ638 (or Δ47).  We present here our parallel project to develop a novel dual laser isotope analyzer capable of measuring multiple carbon dioxide isotopic signatures simultaneously.   Specifically, we simultaneously measure the isotopic abundances of the three most abundant clumped isotopologues (Δ638, Δ637 and Δ828) as well as 17O oxygen excess or Δ17O.  Δ638 and Δ828 correspond to the quantities Δ47 and Δ48 when measured by isotope ratio mass spectroscopy (IRMS).   Δ17O is very difficult to measure with IRMS and Δ637 has not been previously measured with any technique to the best of our knowledge.  The new instrument utilizes carefully chosen spectral windows, operates at low sample pressure and exploits automated laser frequency hopping.  This prototype instrument simultaneously measures seven isotopologues of carbon dioxide: 626, 636, 628, 627, 638, 637 and 828.  Our preliminary results for Δ828 (or Δ48) are displayed as an Allan-Werle plot which shows that the precision in the measurement of Δ828 is ~0.09‰ for a single 3 minute sample measurement referenced to a working reference gas.  The plot shows that instrumental drift is very small over periods of several hours and that the precision can be improved to 0.03‰ by processing 10 sub-samples or to 0.01‰ by processing 100 sub-samples.  These measurements are preliminary and somewhat idealized but show promise for this new technique.

How to cite: Nelson, D., Herndon, S., Wang, Z., Quade, J., and Dettman, D.: TILDAS measurement of multiple clumped isotope ratios in carbonates: progress and new horizons, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9499, https://doi.org/10.5194/egusphere-egu23-9499, 2023.

09:55–10:05
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EGU23-10066
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On-site presentation
Mathieu Daëron

For fundamental thermodynamic reasons, 13C-18O bonds in carbonate minerals formed under isotopic equilibrium conditions are more abundant than predicted for a random distribution of isotopes, yielding positive Δ47 clumped-isotope signatures which decrease as a function of formation temperature [1]. Although most Earth-surface carbonates are unlikely to achieve complete isotopic equilibrium, Δ47 values of many biogenic and abiotic calcites formed under very different crystallization conditions (and with irreconcilable water-calcite oxygen-18 fractionation laws) appear to follow indistinguishable temperature calibrations, as independently documented by various groups over the years [e.g., 2-4]. That is not to say that all groups agree on a single calibration linking Δ47 and temperature, and a recent comparison of 14 reprocessed calibration studies still found evidence for statistically significant inter-laboratory discrepancies [3]. Rigorous statistical tests aiming to prove or disprove consistency between Δ47 calibrations are particularly challenging because of potentially large and non-independent analytical errors associated with standardization procedures [5], and even in some cases by large correlations in the uncertainties of estimated formation temperatures, making classical least-squares regression approaches ill suited to model these calibration data sets.

Here I propose a new formulation for least-squares regression of data with an arbitrarily complex covariance structure linking all predictor and response observations, generally applicable to all sorts of geochemical data. I use this “Omnivariant Generalized Least-Squares” (OGLS) approach to compare 7 published Δ47 calibration data sets which have been (re)processed according to the newly established InterCarb Carbon Dioxide Equilibrium Scale (I-CDES), supposedly allowing robust comparisons between Δ47 measurements across laboratories [6]. None of these reprocessed calibration data sets are found to deviate significantly from a single, unified regression line, with an overall reduced chi-squared statistic (adjusted for data covariance according to OGLS) of 0.8 consistent with slightly overestimated uncertainties on temperature constraints. This finding marks another milestone in the 17-year-long progress of Δ47 thermometry, which has now solved most of the methodological challenges standing in the way of its widespread application to many scientific issues. In short: carbonate clumped-isotope thermometry is all grown up now.

[1] Schauble et al. (2006) 10.1016/j.gca.2006.02.011
[2] Kele et al. (2015) 10.1016/j.gca.2015.06.032
[3] Petersen et al. (2019) 10.1029/2018GC008127
[4] Anderson et al. (2021) 10.1029/2020GL092069
[5] Daëron (2021) 10.1029/2020GC009592
[6] Bernasconi et al. (2021) 10.1029/2020GC009588

How to cite: Daëron, M.: Making the Case for Reconciled Δ47 Calibrations Using Omnivariant Generalized Least-Squares Regression, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10066, https://doi.org/10.5194/egusphere-egu23-10066, 2023.

10:05–10:15
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EGU23-12216
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ECS
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On-site presentation
Justin Chaillot, Mathieu Daeron, Mathieu Casado, Amaelle Landais, Marie Pesnin, and Samir Kassi

Oxygen-17 excess (Δ17O) in carbonate minerals can provide valuable insights into past continental and marine environments, long-term trends in the temperature and oxygen-isotope composition of ancient oceans, isotopic disequilibrium effects in biogenic and abiotic carbonates, and cryptic diagenesis. Triple oxygen isotope analyses of carbonates and/or CO2 using isotope-ratio mass spectrometers (IRMS) remain challenging, however, because of isobaric interference between 16O13C16O and 16O12C17O. Using spectroscopic methods, the abundance of each CO2 isotopologue may be directly quantified, potentially providing simple, non-destructive measurements of δ13C, δ18O and Δ17O on small samples of CO2.

Here we report new data characterizing the application of VCOF-CRDS (V-shaped Cavity Optical Feedback - Cavity Ring Down Spectroscopy [1]) to the analysis of small samples (<40 μmol) of pure CO2, as typically produced by phosphoric acid digestion of carbonate minerals.

Instrumental drifts from various sources are observed to bias apparent isotopic abundances by a few tens of ppm, but these drifts are slow enough that they may be precisely monitored and corrected for by repeated analyses of a working gas interspersed between other analyses, requiring only ~8 mn per aliquot and 30 mn between consecutive “unkown” analyses. This approach was tested by analyzing repeated aliquots of another CO2 tank with a different isotopic composition, yielding instrumental repeatabilities of 12 ppm, 13 ppm and 7.4 ppm for δ13C, δ18O and Δ17O, respectively (95 % CL, Nf = 66).

The accuracy of our measurements was tested over a wide range of Δ17O values spanning 130 ppm, by analyzing CO2 equilibrated at 25 °C with different waters whose triple oxygen compositions were independently constrained in the SMOW-SLAP scale by IRMS measurements and by simple nonlinear mixing predictions. We find that our Δ17O measurements are well within analytical uncertainties of predicted values (RMSE = 1.2 ppm), with analytical repeatabilities (including isotopic equilibration and gas manipulation) of 8.6 ppm (95 % CL, Nf = 27).

We will also report the results of our ongoing investigation regarding the isotopic fractionation and analytical noise associated with different acid digestion protocols at different reaction temperatures, and the triple oxygen composition of various international reference materials already used for δ13C, δ18O, and clumped-isotope measurements.

Based on these results, we conclude that VCOF-CRDS offers excellent accuracy, along with state-of-the-art levels of analytical precision/linearity, for straightforward analyses of 17O excess in CO2, water, and carbonate minerals.

[1] Stoltmann et al. (2017) 10.1021/acs.analchem.7b02853

How to cite: Chaillot, J., Daeron, M., Casado, M., Landais, A., Pesnin, M., and Kassi, S.: Triple oxygen isotope analyses of carbon dioxide, water and carbonates by VCOF-CRDS technique, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12216, https://doi.org/10.5194/egusphere-egu23-12216, 2023.

Posters on site: Tue, 25 Apr, 16:15–18:00 | Hall X2

X2.135
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EGU23-5196
Kye-Hun Park and Youngji Ha

There has been considerable debate as to whether the Korean peninsula has evolved as part of the Sino-Korean Craton since Neoarchean or whether it is a product of the amalgamation of several continental fragments in the early Mesozoic Era. The relationship between the Neoproterozoic Okcheon Metamorphic Belt (OMB) and the Early Paleozoic Tabaeksan Basin (TB) in the central region of the Korean Peninsula has the potential to provide an answer to this question. Various carbonate rocks appear in OMB, showing unique carbon isotope values ​​according to their geologic age.

The Hyangsanni Dolomite is distributed around the Gyemyeongsan Formation with metavolcanics of about 860 Ma. The Hyangsanni Dolomite has δ13C values between +2.9 ‰ and +6.2 ‰, markedly higher than the Cambro-Ordovician values, and are consistent with the Neoproterozoic values. Considering the low values ​​of 86Sr/87Sr, the deposition period of the Hyangsanni Dolomite is judged to be Tonian before the Sturtian Glaciation.

The Geumgang Limestone has a maximum thickness of several tens of meters adjacent to the diamictite layer proposed as a glacial deposit but shows a very extensible distribution. The δ13C values ​​of the Geumgang Limestone range from -12.25 to -7.88 ‰, suggesting that they may be cap carbonates. However, whether their deposition was related to the Sturtian Glaciation or the Marinoan Glaciation is not yet known.

Between the Cryogenian Seochangri Formation of OMB and the Cambrian Jangsan Formation of TB are carbonate rocks previously considered Ordovician. However, carbon and oxygen isotope values analyzed in this study require different interpretations. Zones with δ13C values ​​ranging from -3.4 to +1.3 ‰ agree with Ordovician seawater values. However, over a larger area, δ13C values ​​show mostly positive values ​​from +1.9 to +7.8 ‰. Also, a significant negative excursion of δ13C values ​​down to -6.9 ‰ occurs near the highest values ​​measured. These values correlate with Ediacaran or Early Cambrian carbonates better than Ordovician seawater. It is the first to discover the possible carbonate rocks of Ediacaran or Early Cambrian in South Korea, supporting that the Neoproterozoic OMB and Early Paleozoic TB have a tectonic evolutionary history of continuous deposition rather than an assembly of different continental fragments.

How to cite: Park, K.-H. and Ha, Y.: Carbon Isotopic Composition of Carbonates of the Okcheon Metamorphic Belt in South Korea from Neoproterozoic to Early Cambrian Potential: Geological and Tectonic Significance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5196, https://doi.org/10.5194/egusphere-egu23-5196, 2023.

X2.136
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EGU23-12645
Inigo Andreas Müller, Fabio Messori, Marcel Guillong, Giovan Peyrotti, Michael Schirra, Elias Samankassou, Ulf Linnemann, Mandy Hofmann, Johannes Zieger, Agathe Martignier, Anne-Sophie Bouvier, Torsten Venneman, Kalin Kouzmanov, and Maria Ovtcharova

The final stage of the Proterozoic, the Ediacaran, shields fascinating insights on the development and dispersal of complex metazoans related to dramatic compositional changes in the atmosphere and hydrosphere.  Alternating sequences of siliciclastic and carbonate rocks of the Namibian Nama basin record the final stage of the Ediacaran and contain a vast amount of soft-bodied fauna, as well as some of the first biocalcifying organisms. However, the sparsity of ash beds at the base of the Nama group, preclude accurate and precise constraints on the onset of the Ediacaran biota in Nama group and correlation with chemo stratigraphic records worldwide.  

Due to the scarcity of ash layers, we apply U-Pb dating to carbonate rocks especially from the lower stratigraphic sections of the Nama Group combining the spatial resolution of LA-ICP-MS and the high-precision ID-TIMS U-Pb dating. The combination with mineralogical and geochemical techniques (d13C, d18O, XRD, SEM, EPMA, CL imaging, LA trace element transects, Raman spectroscopy, clumped isotope thermometry, QEMSCAN, SIMS) enables us to better understand the nature of the analyzed carbonates to distinguish between more pristine and diagenetic phases.

This study elaborates on the potential and limitations of carbonate U-Pb dating for improved stratigraphic correlation on these ancient pre-Cambrian marine carbonates from the Nama Group.

How to cite: Müller, I. A., Messori, F., Guillong, M., Peyrotti, G., Schirra, M., Samankassou, E., Linnemann, U., Hofmann, M., Zieger, J., Martignier, A., Bouvier, A.-S., Venneman, T., Kouzmanov, K., and Ovtcharova, M.: The onset of the Ediacaran Nama Group sedimentation in Namibia?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12645, https://doi.org/10.5194/egusphere-egu23-12645, 2023.

X2.137
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EGU23-16279
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ECS
Aileen Doran, Steven Hollis, Julian Menuge, Alina Marca, Paul Dennis, and David van Acken

With the introduction of climate action plans by many countries globally, the development of green technologies like electric vehicles and renewable infrastructure is expected to increase. These technologies are resource intensive, meaning we will require increased production of metals to meet the growing demands of society. However, discovery and exploration rates are not increasing at the same rate as demand. Improving understanding of ore system formation and evolution is a crucial step in aiding future exploration, to help supply these critical resources.

In hydrothermal systems, carbonate minerals (e.g., calcite and dolomite) are often associated with all stages of ore formation, with fluid inclusion thermometry and carbon-oxygen (C-O) isotope ratios traditionally used to study fluid temperature and composition. However, there are several challenges still remaining with these techniques, with fluid inclusions often too small, ruptured or deformed for adequate study. In carbonate minerals, the rare, heavy isotopes 13C and 18O bond or clump more frequently at lower temperatures, with the magnitude of clumping inversely temperature-dependent. Measurement of clumped C-O isotope ratios, using gas source isotope spectrometry, simultaneously yields carbonate δ13C and δ18O values and generates mineral precipitation temperatures, allowing fluid δ18O to be directly calculated. While traditionally applied to low temperate environments, recent applications have included hydrothermal ore systems to study fluid temperature and mixing. When combined with other techniques, such as strontium isotopes, new understanding of the sources, movement and compositional evolution of fluids can be deciphered.

Recent clumped C-O and strontium isotope analyses of ore-related carbonates from the Lisheen and Galmoy deposits, southern Irish Zn-Pb ore field, have facilitated the study of fluid sources, temperatures, mixing, and modification. Lisheen and Galmoy are  hosted in a belt of regionally dolomitized Lower Carboniferous (Mississippian) marine limestones, cut by a series of NE-SW-trending ramp-relay normal faults. Study of these deposits reveals that early dolomitizing and later hydrothermal fluids are part of a complex multistage continuum, with phases of fluid mixing, compositional buffering due to dissolution, and isotope resetting. Consequently, studies of carbonates in other deposits may yield new insights into ore formation, ultimately helping exploration for crucial resources.  

How to cite: Doran, A., Hollis, S., Menuge, J., Marca, A., Dennis, P., and van Acken, D.: Interpreting hydrothermal clumped isotope temperatures in the Irish Zn-Pb ore field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16279, https://doi.org/10.5194/egusphere-egu23-16279, 2023.

X2.138
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EGU23-15731
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ECS
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Ke Lin, Sidney R. Hemming, Guleed Ali, In-Tian Lin, Chih-Chieh Su, Scott W. Stine, N. Gary Hemming, and Xianfeng Wang

Uranium concentrations and 234U/238U activity ratios (δ234U) of Earth’s surface waters can provide independent and complementary information on changes in weathering regime and hydroclimate. The response of δ234U variation in surface waters in US Great Basin to climate change however remains unclear, which brings ambiguities in interpreting δ234U in aquatic carbonate deposits. Here, we analysed U concentration and δ234U in a suite of surface waters (creeks, springs and lake) as well as tufa deposits from the last glacial lake highstands in the Mono Basin, California, USA to assess the modern uranium budget in the lake water and the controlling factors on its δ234U. We find that U concentrations in groundwater springs are about one order of magnitude higher than those of creek waters. Hence, even though springs only deliver about 15% of annual inflow to the lake, they contribute 70% of U in the lake water. The residence time of U in lake water is calculated to be approximately 15,000 years, on the same order as those of Li, Na, and Cl, but significantly longer than those of alkaline earth elements. The δ234U in Mono Lake water is 180‰, same as in modern-day tufa deposits. The δ234U in lake highstand tufas is ~ 220‰, suggesting much more enhanced physical weathering associated with mountain glacial activities in the basin, even though chemical weathering was also stronger due to increased precipitation. On the other hand, the higher δ234U values (~ 250‰) in modern creeks and springs is consistent with the overall dry environment and stronger physical weathering in the basin. The 40‰ decrease in δ234U of lake water however cannot be explained by radiative decay. We hypothesis that lake water was more frequently stratified in the past, during the last glacial in particular, and the resulted anoxic environment in deep lake water has probably facilitated precipitations more enriched in 234U. 

How to cite: Lin, K., Hemming, S. R., Ali, G., Lin, I.-T., Su, C.-C., Stine, S. W., Hemming, N. G., and Wang, X.: Variability of (234U/238U) in surface water and tufa deposits: A study in the Mono Basin, California, USA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15731, https://doi.org/10.5194/egusphere-egu23-15731, 2023.

X2.139
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EGU23-15952
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ECS
Adhipa Herlambang, Ardiansyah Koeshidayatullah, Chaojin Lu, Abduljamiu Amao, Abdulwahab Bello, Faisal Al-Ghamdi, Muhammad Malik, and Khalid Al-Ramadan

The Ediacaran Period (635-538 Ma) was marked by considerable tectonic activity, including the end of the Pan-African episode – a long interval of mountain building, rifting, and reorganization spanning most of the Neoproterozoic Era. In Saudi Arabia, the Ediacaran outcrops were developed and preserved in several isolated half-grabens linked to the Ediacaran to early Cambrian Najd strike-slip fault system. This fault system manifested, particularly in the study area, as intensive fractures with a distinctive crack-seal veins morphology. Understanding the mechanism and origin of such fractures could provide unique insights into the structural evolution and paleo fluid flow throughout the history of the Arabian Plate. However, no studies have focused on different structural-controlled diagenetic processes in the Neoproterozoic sequences across the Arabian Plate. Here, we examined precipitated veins along a well-exposed 300 m thick Ediacaran host rock exposure by integrating high-resolution geochemical analyses, carbonate clumped isotopes, fluid inclusions, advanced petrography analysis of Cathodoluminescence microscopy to unravel the structural diagenesis of these Ediacaran strata. The δ18O and δ13C of the carbonate host rocks vary from -11.79 to -7.83‰, and -0.58‰ to 1.1‰, respectively. The estimated paleotemperature of the host rock derived from the clumped isotope is 47-60°C. Furthermore, the current results show that the calcite veins appear in different stages, orientations, geometries, and mineralogy. The δ18O and δ13C of the crack-seal veins vary between -11.2 to -7.8 ‰ and -2.9 to 1.9‰, respectively. The estimated clumped-derived paleotemperature of this vein is 95°C, even higher up to 136°C by utilizing the fluid inclusions. On the other hand, the Mn-rich later phase veins, which cross-cut the crack-seal veins, indicate an isotopic composition of -10.9 to -10.6‰ for δ18O and -18.2 to -15‰ for δ13C, with the estimated paleotemperature of 74-84°C. Hence, we argue that the structural diagenesis history in the study area comprises several distinct tectonic events and fluid circulation members along the fractures associated with different stages of basin evolution. Our findings, for the first time, offer a new understanding of paleo fluid circulation and also highlight the multi-proxy’s potential for investigating the structural diagenesis of calcite veins in the Ediacaran host rock in Arabia.

How to cite: Herlambang, A., Koeshidayatullah, A., Lu, C., Amao, A., Bello, A., Al-Ghamdi, F., Malik, M., and Al-Ramadan, K.: Crack-seal veins: records of 600-million-year complex tectonic and fluid flow evolution in Saudi Arabia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15952, https://doi.org/10.5194/egusphere-egu23-15952, 2023.

Posters virtual: Tue, 25 Apr, 16:15–18:00 | vHall GMPV/G/GD/SM

vGGGS.7
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EGU23-5345
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ECS
Shitou Wu, Yueheng Yang, Rolf Romer, Nick M W Roberts, and Zhongwu Lan

U-Pb geochronology of calcite using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is an emerging method, with potential applications to a vast array of geological issues. Accurate LA-ICP-MS calcite U-Pb dating requires matrix-matched RMs for the correction of instrumental mass bias of Pb/U ratios. Several materials are currently being used as RMs, including WC-1, Duff Brown Tank, ASH-15, JT, and AHX-1A. In this study, we will give a brief introduction of LA-ICP-MS lab at IGGCAS for carbonate U-Pb dating. Meanwhile we further characterized two calcite reference materials for micro-beam U-Pb geochronology and and C, O isotope ratio measurements. LA-ICP-MS multiple spot analyses (> 400) at different regions of materials reveal that calcite TLM and LSJ07 are homogeneous for the U-Pb age with 220.72 +/-0.98 Ma and 26.54+/-0.41 Ma respectively. SIMS multiple spot analyses (> 100) reveals calcite TLM is homogeneous for the O isotope ratio at mm special resolution. MAT 253 gives a bulk result of δ18O =-14.20 ‰. LA-MC-ICP-MS multiple spot analyses (> 200) reveals calcite TLM and LSJ07 are homogeneous for the C and O isotope ratio at mm special resolution. MAT 253 gives bulk results of δ13C =-1.53 ‰ andδ13C =-0.33 ‰ for TLM and LSJ07 respectively. These two materials represent a useful addition to the currently distributed WC-1, Duff Brown Tank, ASH-15, JT, and AHX-1A for micro-analytical techniques of U-Pb geochronology and C, O isotope ratio measurements.

How to cite: Wu, S., Yang, Y., Romer, R., Roberts, N. M. W., and Lan, Z.: Calcite TLM and LSJ07: two natural reference materials for micro-beam U-Pb geochronology and C, O isotope ratio measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5345, https://doi.org/10.5194/egusphere-egu23-5345, 2023.

vGGGS.8
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EGU23-5865
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ECS
Binsong Zheng, Renjie Zhou, Chuanlong Mou, Jianxin Zhao, and Daryl Howard

Large gas fields are hosted in Upper Permian reef-dolostone bodies in Sichuan Basin, southwest China, among which the Puguang gasfield is the largest marine-carbonate gas system in China. The reservoir rocks are mainly composed of intensively dolomitized sponge-reefs constructed within platform margin reef facies in northern Sichuan Basin. Although major reservoir spaces consist of intercrystal pores, dissolved pores and vugs, the knowledge regarding the evolution of porosities is still limited. Using multiple methods, this study focuses on characterising different phases of carbonates (calcite and dolomite) to understand the dolomitization model and porosity evolution of the Upper Permian Panlongdong reef cropped out in northeastern Sichuan Basin. Two-dimensional high-resolution visualization of element contents in reef dolostones was provided by synchrotron-radiation Micro X-ray fluorescence elemental mapping. O and Sr isotope analysis was carried out to trace the nature of fluids during dolomitization. Laser ablation ICP-MS U-Pb dating was performed on dolomite minerals and secondary calcite cements. Our results suggest that: (1) dolomitization of the reef occurred in the early Middle Triassic (~245 Ma) due to the downward reflux of hypersaline seawater rich in Mg2+, accompanied by a significant increase in porosity because of the selective dissolution of low-Mg calcites; (2) in the Late Triassic, continental collision between South and North China plates induced uplifting and formation of a large quantity of (micro)fractures in northern South China, followed by Sr-depleted freshwater passing through the reef, leading to precipitation of secondary calcite cements (~206 Ma).

How to cite: Zheng, B., Zhou, R., Mou, C., Zhao, J., and Howard, D.: Dating and characterizing carbonate rocks in Upper Permian reef-dolostone reservoir systems in Sichuan Basin, southwest China: implications for porosity evolution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5865, https://doi.org/10.5194/egusphere-egu23-5865, 2023.

vGGGS.9
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EGU23-10706
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ECS
Xingyu Chen, Renjie Zhou, David Wood, Daniel Stirling, Kamalendra Jhala, Ira Friedman, Matt Valetich, and Lizzy Philippa

This study investigates carbonate veins in five drill cores archived at Geological Survey of Queensland from NW Queensland, ~100 km south of Mt Isa, with geochemical and geochronologic approaches in order to characterise origins of fluids and their mineralisation potentials. Carbonate veins are mostly hosted in Proterozoic age (approximately 1800-1650 Ma) supra-crustal rocks, which are inferred from geophysics to be covered by 350 to 2,000 m of younger sedimentary rocks of the Eromanga and Georgina basins. Data regarding the nature of fluid activities is important for comparison between the undercover southern Mt Isa and outcropped Mt Isa mineral district, which is a world-class mineral province.

Multiple-phase carbonate veins (mostly calcite and dolomite) are identified, including late formed brittle veins, pyrite/chalcopyrite mineralisation-bearing carbonate veins, and calcite hosted in crackle breccias. Samples are prepared into one-inch polished mounts and studied with SEM-EDS, and in situ laser ablation ICP-MS for geochemical and U-Pb geochronological studies. Relatively pure calcite phases are also prepared with microdrill for stable isotope C and O analysis. Trace element datasets suggest enrichments in rare earth elements and ytterbium (REE+Y) with distinct negative Eu anomalies. Stable isotopes range ~-5 to – 15 (δ13CVPDB‰) and ~10 to 25 (δ18OVSMOW‰). Trace element data, Yb/La and Yb/Ca ratios, and stable isotope signatures imply that these carbonate veins have hydrothermal origins. 206Pb/238U geochronology data has indicated multi-phase calcite formation ranging from the late Neoproterozoic to Cretaceous. Our results provide a novel dataset to demonstrate the use of carbonate veins in revealing fluid activities in a mineral district and help the future exploration of critical mineral deposits in undercover southern Mt Isa when interpreted against regional structural data and well-documented mineralisation events in the northern Mt Isa district.

 

How to cite: Chen, X., Zhou, R., Wood, D., Stirling, D., Jhala, K., Friedman, I., Valetich, M., and Philippa, L.: Geochemical and geochronologic investigations into carbonate veins from historical drill cores in undercover Mt Isa, NW Queensland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10706, https://doi.org/10.5194/egusphere-egu23-10706, 2023.

vGGGS.10
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EGU23-13798
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ECS
Mustafa Kaya, Mustafa Kumral, Amr Abdelnasser, Cihan Yalçın, Sercan Öztürk, Hatice Nur Bayram, and Beril Tanç-Kaya

This work deals recently with the carbon (δ13C) and oxygen (δ18O) isotopic variations in the calcite associated with the hydrothermal mineralization to comprehend the nature of the ore fluid and its source and the evolution of the Yolindi Fe-Cu skarn deposit at North of Biga peninsula (NW Turkiye). The Yolindi area is made up of Torasan Formation (marble, hornfels, phyllite, and schist) which was intruded by Oligocene Hallaçlar volcanic rocks and later early Miocene Şaroluk plutonic rocks. The Yolindi Fe-Cu skarn deposit has been formed along the eastern contact of Şaroluk pluton with the Torasan Formation having widespread prograde and/or retrograde skarn, silicic, and carbonate (calcite) alteration. The prograde skarn is less observed and characterized by formation of garnet with subordinate magnetite. While, the retrograde skarn is highly extensive having epidote, actinolite, chlorite, and carbonate including pyrite, magnetite, chalcopyrite, and specular hematite with subordinate sphalerite and galena. Malachite, azurite, goethite, hemimorphite, and cerussite represent the supergene minerals which locally replaced Fe-oxide and Fe-Cu±Zn±Pb sulfide minerals. At the Yolindi Fe-Cu skarn deposit, carbon and oxygen isotope ratios of calcite minerals from the exoskarn zone are -15.5 to -2.0 ‰ relative to PDB and 0.9 to 17.9 ‰relative to V-SMOW, respectively. Furthermore, it was inferred from the calculated carbon isotopic composition of an ore-forming fluid (δ13CCO2 = -12.7 to +0.8 ‰) that the carbon in the fluid is identical to the reduced carbon in sedimentary and metamorphic rocks. However, the calculated fluid's δ18OH2O values—which vary from 0.9 to 17.2 ‰VSMOW—indicate a mixture of metamorphic and magmatic origins for the hydrothermal fluid. This fluid mixing which has high range of C-O isotopic compositions has been due to a temperature effect along with either CO2 outgassing or fluid/rock interactions. Additionally, the mineralizing fluid is most likely derived from the metamorphic dehydration of carbonate rocks in the Torrasan Formation during Yolindi skarn formation.

Keywords: carbon (δ13C) and oxygen (δ18O) isotope; Fe-Cu Yolindi skarn deposit; Biga peninsula; NW Turkiye

How to cite: Kaya, M., Kumral, M., Abdelnasser, A., Yalçın, C., Öztürk, S., Bayram, H. N., and Tanç-Kaya, B.: Evolution of the hydrothermal fluids of the Yolindi Fe-Cu skarn deposit, Biga peninsula, NW Turkiye: Evidence from carbon-oxygen isotopic variations of calcite minerals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13798, https://doi.org/10.5194/egusphere-egu23-13798, 2023.