Article
Geochemistry & Geophysics
Christoph Spoetl, Yuri Dublyansky, Gabriella Koltai, Charlotte Honiat, Lukas Plan, Thomas Angerer
Summary: This study demonstrates that geochemical analysis of cave wall rock samples can identify hypogene karstification and provide further insights into the temperature and provenance of paleowater, as well as the source of its dissolved inorganic carbon.
Article
Geochemistry & Geophysics
Lucile Roue, Florian Kurzweil, Martin Wille, Antje Wegwerth, Olaf Dellwig, Carsten Munker, Ronny Schoenberg
Summary: The study explores the potential of stable W isotopes as a paleoredox proxy, with an analysis of Precambrian igneous rocks and modern Black Sea sediments to validate its applicability. Results indicate that the δW-186/184 values of black shales can help distinguish between different depositional environments.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2021)
Article
Geology
C. A. Partin, Y. M. DeWolfe, T. Magee
Summary: This study aims to understand the origin of sediment-hosted Pb-Zn mineralization in the Marmorilik and Qaarsukassak formations through petrographic analysis and various isotope analyses, revealing a Paleoproterozoic age for both mineralizing events. The Marmorilik Formation is most consistent with a Mississippi Valley-type deposit model, while the Qaarsukassak Formation is most consistent with a sedimentary exhalative mineralization model. Results also show that the Marmorilik mineralization represents the oldest documented MVT deposit outside of the Neoarchean-Paleoproterozoic Transvaal basin in South Africa.
ORE GEOLOGY REVIEWS
(2021)
Article
Geosciences, Multidisciplinary
Julie Ngwal'ghoubou Ikouanga, Claude Fontaine, Franck Bourdelle, Ahmed Abd Elmola, Jeremie Aubineau, Olabode M. Bankole, Laurie Reisberg, Anne-Catherine Pierson-Wickmann, Armelle Riboulleau, Alain Trentesaux, Claude Laforest, Alain Meunier, Abderrazak El Albani
Summary: The taphonomy of early soft-bodied organisms in Palaeoproterozoic sediments is still not well understood. The discovery of multicellular organism macrofossils in black shales in the Gabonese Francevillian Basin provides an exceptional example of fossil preservation. This study aims to provide a better understanding of soft-bodied organism preservation through mineralogical and textural analysis.
PRECAMBRIAN RESEARCH
(2023)
Article
Geochemistry & Geophysics
Kaarel Mand, Noah J. Planavsky, Susannah M. Porter, Leslie J. Robbins, Changle Wang, Timmu Kreitsmann, Kart Paiste, Paarn Paiste, Alexander E. Romashkin, Yulia E. Deines, Kalle Kirsimae, Aivo Lepland, Kurt O. Konhauser
Summary: There is a gap in time between the oxygenation of the atmosphere 2.4 billion years ago and the first widely-accepted fossil evidence for complex eukaryotic cells less than 1.7 billion years ago. The study analyzed chromium-based oxygen proxies in a core from the Onega Basin in Russia and found evidence of higher and more stable oxygen levels in the Paleoproterozoic. This suggests that the delay in the evolution of complex cells was not due to oxygen limitation but could be attributed to other factors or simply the time required for such biological innovations to occur.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Energy & Fuels
Qian Wang, Shifeng Dai, David French, Baruch Spiro, Ian Graham, Jingjing Liu
Summary: The thermal effects of a quartz intrusion during the Yanshanian Orogeny on coal mines in the Daqingshan Coalfield in Inner Mongolia have caused changes in coal quality and chemical characteristics. As the distance from the intrusion decreases, there is an increase in vitrinite reflectance values and a decrease in volatile matter content in the coal mines. The organic carbon isotopes in the coals also vary with the distance from the intrusion.
INTERNATIONAL JOURNAL OF COAL GEOLOGY
(2023)
Article
Geochemistry & Geophysics
Yan Yuan, Tianyu Chen, Feifei Zhang, Yuanyuan Liu, Guolin Xiong, Guang-Yi Wei, Tais W. Dahl, Wen Yan, Hong-Fei Ling, Hai Cheng, Shu-Zhong Shen
Summary: The uranium isotope ratio in marine carbonates is an important tool for reconstructing past oceanic redox conditions. However, diagenetic processes may complicate this proxy by introducing isotopically heavy uranium into the carbonates. This study quantifies the valence states of trace amounts of uranium in geological carbonate samples and finds that modern coral carbonates faithfully record uranium from seawater. Surprisingly, drill core samples from a modern coral carbonate platform show a significant positive correlation between a specific valence state of uranium and the uranium isotope ratio, suggesting the presence of this valence state in marine carbonates and its influence on the uranium isotope ratio. The study suggests that coupled valence and isotope analyses of uranium in marine carbonates could provide critical constraints for reconstructing marine redox evolution.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2023)
Article
Geochemistry & Geophysics
Tian-Hao Wu, Sheng-Ao Liu
Summary: Recycled carbonates are found to be an important oxidizer for the deep mantle, and their influence on the extraction of mantle sulfides can be effectively tracked by Fe and Cu isotopic systematics.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Christophe Thomazo, Pierre Sansjofre, Olivier Musset, Theophile Cocquerez, Stefan Lalonde
Summary: The study introduces a new protocol for carbonates analysis using a laser calcination system, which reduces preparation steps and analysis time significantly while offering spatially resolved analysis at the mm scale. The new method based on a fiber-coupled laser diode device shows accurate and reproducible results for C and O isotopic characterization of natural carbonates. The study also demonstrates that physical effects during calcination do not introduce isotopic fractionation for C and a constant isotopic offset for O within a range of isotopic compositions and mineral matrices.
Article
Geosciences, Multidisciplinary
Lameed O. Babalola, Abdullah M. Alqubalee, Michael A. Kaminski, Osman M. Abdullatif, Mohamed O. Abouelresh
Summary: This study investigates stable oxygen and carbon isotope data from the Middle Jurassic Dhruma Formation in central Saudi Arabia to examine paleoenvironments and diagenesis impacts on isotopic signals in sedimentary rocks.
INTERNATIONAL JOURNAL OF EARTH SCIENCES
(2023)
Article
Geosciences, Multidisciplinary
Wenlong Pei, Jiayue Wang, Xinling Wang, Liang Du, Yipeng Wang, Yujin Fan, Rui Zhang, Tiegang Li, James Russell, Fan Zhang, Xiaoxiao Yu, Zhiyong Liu, Minglei Guan, Qi Han
Summary: The tropical western Pacific (TWP) is important in modulating the global climate through solar radiation, sea surface temperature, and monsoon circulation. Fluctuations in marine primary productivity in the TWP can impact the global carbon cycle. However, there is currently a lack of isotopic geochemical evidence to reconstruct changes in productivity in the western Pacific warm pool (WPWP).
Article
Geochemistry & Geophysics
Mingyu Zhao, Lidya G. Tarhan, Yiyue Zhang, Ashleigh Hood, Dan Asael, R. Pamela Reid, Noah J. Planaysky
Summary: Carbonate zinc isotopes are increasingly used to track changes in seawater zinc isotopic composition. Recent studies, particularly under the GEOTRACES program, have expanded our understanding of zinc behavior in the water column. However, the incorporation of water-column zinc isotopic signals into carbonate sediments is still at an early stage.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
Ziyao Fang, Wei Liu, Tao Yao, Gentao Zhou, Shiqiang Wei, Liping Qin
Summary: Chromium isotope compositions in marine carbonates have been used to trace the evolution of oxygen levels in the atmosphere and ocean. Recent studies have shown that chromium in natural carbonates is mostly in the form of trivalent chromium (Cr(III)). However, the behavior of Cr(III) in carbonate deposition environments is still not well understood. This study conducted coprecipitation experiments to investigate the behavior of Cr(III) with calcium carbonate. The results suggest that Cr(III) is incompatible with the calcite crystal lattice and is mostly adsorbed on the crystal surface or exists as amorphous Cr hydroxide. The presence of Cr(III) can also affect the polymorph selection of calcium carbonate, hindering its transformation to calcite. The findings indicate that post-depositional processes can greatly influence the Cr isotope compositions in sedimentary carbonates, and caution should be taken when using Cr isotope compositions for paleoenvironment reconstruction.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Geochemistry & Geophysics
Sebastian Jimenez-Rodriguez, Jay Quade, Matthew Dettinger, Katharine W. Huntington, Julia R. Kelson
Summary: This study highlights the limitations of using carbonate archives in reconstructing past elevations in the Central Andes. The results show that paleoaltimetry estimates based on carbonates significantly underestimate the results obtained from volcanic glass using stable hydrogen isotopes.
Article
Geochemistry & Geophysics
Jian-Qiang Liu, Li-Hui Chen, Xiao-Jun Wang, Xiao-Yu Zhang, Gang Zeng, Saskia Erdmann, David T. Murphy, Kenneth D. Collerson, Tsuyoshi Komiya, Lukas Krmicek
Summary: The study further examines the petrogenesis of Gaussberg lamproites using new Mg and Zn isotopic data, suggesting a source from recycled crustal materials containing sedimentary carbonates rather than post-magmatic alteration or crustal contamination. The involvement of subducted dolomite in the source of the lamproites can explain their anomalous Mg and Zn isotopic values.
Article
Geosciences, Multidisciplinary
F. Delpomdor, L. Tack, J. Cailteux, A. Preat
JOURNAL OF AFRICAN EARTH SCIENCES
(2015)
Article
Geography, Physical
Franck Delpomdor, Nicholas Eyles, Luc Tack, Alain Preat
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2016)
Article
Geosciences, Multidisciplinary
Alain Preat, Jean-Pierre Prian, Denis Thieblemont, Rolf Mabicka Obame, Franck Delpomdor
JOURNAL OF AFRICAN EARTH SCIENCES
(2011)
Article
Geosciences, Multidisciplinary
F. Delpomdor, C. Blanpied, A. Virgone, A. Preat
JOURNAL OF AFRICAN EARTH SCIENCES
(2013)
Article
Geosciences, Multidisciplinary
F. Delpomdor, F. Kant, A. Preat
JOURNAL OF AFRICAN EARTH SCIENCES
(2014)
Article
Geography, Physical
Franck Delpomdor, Ulf Linnemann, Ariel Boven, Andreas Gaertner, Aleksey Travin, Christian Blanpied, Aurelien Virgone, Hielke Jelsma, Alain Preat
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2013)
Article
Geography, Physical
Franck Delpomdor, Alain Preat
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2013)
Article
Geosciences, Multidisciplinary
Alain Preat, Kamal Kolo, Jean-Pierre Prian, Franck Delpomdor
PRECAMBRIAN RESEARCH
(2010)