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Oxygen isotope study of the Asuka-881020 CH chondrite II: Porphyritic chondrules Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-10 Daisuke Nakashima, Takaaki Noguchi, Takayuki Ushikubo, Makoto Kimura, Noriko Kita
Oxygen isotope ratios and elemental compositions of porphyritic chondrules and olivine and pyroxene fragments in the Asuka-881020 CH chondrite were analyzed. The oxygen isotope ratios inside individual porphyritic chondrules are homogeneous within the uncertainty, except for relict grains of olivine and low-Ca pyroxene that have distinct oxygen isotope ratios. The average oxygen isotope ratios of the
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Surface properties of schwertmannite with different sulfate contents and its effect on Cr(VI) adsorption Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-09 Chaoping Wang, Kai Chen, Meiling Yin, Yuting Zhou, Qinglin Zhuang, Qianqian Cao, Zhi Dang, Chuling Guo
Sulfate is a critical component of schwertmannite. However, the sulfate content of schwertmannite decreases with the increase in AMD-polluted river pH value, and its impact on the surface properties and Cr(VI) adsorption of schwertmannite remains unclear. To address this issue, different methods, including batch adsorption, N physisorption, scanning electron microscopy (SEM), potentiometric titration
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Effects of particle size and AQDS on the flow of electron equivalents between magnetite and aqueous Fe2+ Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-08 Huan Peng, Zhenli Zhu, Carolyn I. Pearce, Anxu Sheng, Mingjun Nie, Alpha T. N'Diaye, Xin Zhang, Kevin M. Rosso, Juan Liu
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Tracing material transport during subduction inception: Insights from potassium isotopes in the crustal sequence of the Troodos ophiolite Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-08 Qi-Qi Pan, Yan Xiao, Ben-Xun Su, Paul T. Robinson, Wen-Jun Li, Jing Wang, Xia Liu
Potassium (K) isotopic compositions for a suite of crustal rocks (plutonic unit, sheeted dike complex, and volcanic sequence) in the Troodos ophiolite, Cyprus, were determined to investigate fluid-transport processes during subduction inception. The gabbros and plagiogranites in the plutonic unit have restricted K isotopic compositions (0.01–0.20 ‰ and −0.17 to 0.02 ‰, respectively), whereas diabases
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Isotope evidence for the enrichment mechanism of molybdenum in methane-seep sediments: Implications for past seepage intensity Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-07 Meng Jin, Fang Chen, Niu Li, Jörn Peckmann, Ryan Mathur, Linda Godfrey, Duofu Chen
Methane release from marine sediments strongly influences the local seafloor environment and ecosystems, and may impact Earth’s climate system. Recent studies revealed anomalous molybdenum (Mo) enrichment in seep sediments, which was linked to methane release events. Marine seep sediments are a potential sink of Mo for the global ocean, while the mechanisms leading to local Mo enrichment are not fully
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Constraining carbonate diagenesis using clumped isotope temperatures and U-Pb dating: A case study and implications for paleoelevation interpretations in western central Tibet Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-06 Lin Li, Peter DeCelles, Paul Kapp, Carmala Garzione, Jay Quade, Nitzan Yanay
Carbonate rocks are susceptible to diagenesis, and the correct identification of diagenetic features and stages are primary tasks in paleoelevation and paleoclimate studies using carbonate proxies. In this study, we apply three key parameters that include stable isotopes, clumped isotope temperatures, and U-Pb ages to identify different diagenetic stages, i.e., eogenesis, mesogenesis, and telogenesis
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New olivine morphologies in shergottites reveal complex thermal histories of martian magmas Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-06 S.A. Eckley, R.A. Ketcham, Y. Liu, A. Udry, J. Gross
Petrogenetic models of martian magmas reflect the compositional, thermal, and geodynamical evolution of its interior. Most models for shergottite meteorites, which sampled relatively young martian basalts, invoke partial melting in a mantle plume head and filtering of the magma through the crust. Olivine-phyric, poikilitic, and olivine-gabbroic shergottites contain large, Mg-rich olivine crystals that
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Volatiles in melt inclusions from lunar mare basalts: Bridging the gap in the H2O/Ce ratio between melt Inclusions in lunar pyroclastic sample 74220 and other mare samples Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-03 Xue Su, Youxue Zhang
The HO concentration and HO/Ce ratio in olivine-hosted melt inclusions are high in lunar pyroclastic sample 74220 (HO up to 1410 ppmw; HO/Ce up to 77) but lower (HO 10 to 430 ppmw; HO/Ce 0.3 to 9.4) in all other lunar samples studied before this work. The difference in HO concentration and in HO/Ce ratio is absent for other volatile elements (F, S, and Cl) in melt inclusions in 74220 and other lunar
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The role of alkaline silicate-rich fluids in Sn mineralization based on cassiterite solubility experiments Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-03 Qinxia Wang, Renzhi Zhu, Wan-Cai Li, Huaiwei Ni
It is widely accepted that the complexation of Sn with Cl in magmatic-hydrothermal fluids is critical for the formation of endogenic Sn deposits. However, Sn abundance as high as 0.4 wt% has been found in some chlorine-poor but silicate-rich fluid inclusions associated with a Sn-mineralized pegmatite. To examine the role of silicate solutes in Sn mineralization, we measured the solubility of cassiterite
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Constraints on hopanes and brGDGTs as pH proxies in peat Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-01 Valentine Schaaff, Vincent Grossi, Matthew Makou, Yannick Garcin, Pierre Deschamps, David Sebag, Benjamin Ngounou Ngatcha, Guillemette Ménot
pH is one of the major parameters governing peat functioning, and pH variations in modern peatlands affect carbon and methane production and consumption. Paleo-pH reconstructions have been limited thus far, but they could help to better understand peat functioning in variety of settings and also serve as an indirect proxy for climatic and environmental variations such as precipitation. Bacterial hopanes
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Size-dependent dynamics of the internal carbon pool drive isotopic vital effects in calcifying phytoplankton Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-04-01 Nishant Chauhan, Rosalind E.M. Rickaby
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Vivianite oxidation is not photocatalyzed Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-31 Winnie Liu, Zheming Wang, Mark Bowden, Odeta Qafoku, Kevin M. Rosso
Vivianite is a hydrous Fe(II) phosphate mineral found in anoxic environments that plays an integral role in P cycling and environmental biogeochemistry. Imbued in the vivianite literature dating as far back as 1918 is the notion that vivianite is light-sensitive and susceptible to rapid photooxidation induced entirely by solar light. However, despite an exhaustive search, to our knowledge this conventionally
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Experimental investigation of first-row transition elements partitioning between olivine and silicate melt: Implications for lunar basalt formation Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-30 Jie-Jun Jing, Ben-Xun Su, Jasper Berndt, Hideharu Kuwahara, Wim van Westrenen
Fifteen experiments at 1 atm pressure and 1400 °C have been conducted to determine partition coefficients between olivine and silicate melt () of the first-row transition elements (FRTEs, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn), Ga and Ge in the system FeO-CaO-MgO-AlO-SiO (FCMAS). Bulk iron contents are varied between 0 and 10 wt.% FeO, and oxygen fugacity ranges from 2 log units below the iron-wüstite
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Pyrite trace element proxies for magmatic volatile influx in submarine subduction-related hydrothermal systems Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-30 Jan J. Falkenberg, Manuel Keith, Karsten M. Haase, Reiner Klemd, Martin Kutzschbach, Anna Grosche, Maria Rosa Scicchitano, Harald Strauss, Jonguk Kim
Seafloor massive sulfides are modern analogues to ancient volcanogenic massive sulfide deposits, which are particularly enriched in volatile and precious metals (e.g., Te, Au, Ag, Cu, Bi, Se) in subduction-related settings. However, the sources of metals are still poorly constrained, and it remains elusive, whether magmatic volatile influx controls their distribution in submarine hydrothermal systems
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Source and parental melts of poikilitic shergottites: Implications for martian magmatism Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-30 Evan W. O'Neal, A.M. Ostwald, A. Udry, J. Gross, M. Righter, T.J. Lapen, J. Darling, G.H. Howarth, R. Johnsen, D.R. McQuaig
Martian poikilitic shergottites are cumulate rocks that can help advance the understanding of magmatic evolution from near the base of the crust (∼10 kbar) to near-surface conditions. Through a comprehensive petrographic and geochemical study, we aim to better understand poikilitic shergottite formation and the evolution in the martian interior. A suite of poikilitic shergottites, including Northwest
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Nanoscale mechanisms of carboxyl carbon preservation during Fe(II)-induced ferrihydrite transformation Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-29 Fu Liu, Yang Lu, Zhenqing Shi
The persistence of organic carbon (OC) in natural environments is widely attributed to OC associations with minerals such as iron (Fe) minerals. Carboxyl, a critical structure of OC, can form strong complexes with Fe minerals, but it is still largely unknown about the effects of carboxyl groups on the transformation of Fe oxides and the stabilization mechanisms of OC on Fe oxides at nanoscales. In
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Controls on distributions of aluminium, manganese and cobalt in the South Atlantic Ocean along GEOTRACES transect GA10 Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-28 Xue-Gang Chen, Angela Milne, Jessica K. Klar, Martha Gledhill, Maeve C. Lohan, Yu-Te Hsieh, Gideon M. Henderson, E. Malcolm S. Woodward, Eric P. Achterberg
Trace metals (TMs) manganese (Mn), cobalt (Co), and aluminium (Al) have important geochemical and biological roles in the ocean. Here, we present full depth profiles of dissolved (d) and particulate Al, Mn, and Co along the latitude of 40 °S in the South Atlantic Ocean from the GEOTRACES GA10 cruises that operated in austral spring 2010 and summer 2011. The region is characterized by enhanced primary
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Incipient Dissolution of Emplaced Forsterite and Fayalite Records the Effects of Climate, Mineral Composition, and Crystallographic Orientation Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-28 Feldman AD, Hausrath EM, Burnley P, Rampe EB, Morris RV, Munoz J, Uyeda GH, Seward G
To investigate the effects of environment, composition, and crystal orientation on incipient surface alteration of forsterite and fayalite in a natural environment, polycrystalline forsterite and fayalite samples were emplaced in Mg/Fe-rich and Al-poor ultramafic soils under subarctic (Tablelands in Newfoundland, Canada; 3.9 ⁰C and ∼120 cm precipitation/year), Mediterranean (Klamath Mountains, California;≤12
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Young KREEP-like mare volcanism from Oceanus Procellarum Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-28 Zaicong Wang, Keqing Zong, Yiheng Li, Jiawei Li, Qi He, Zongqi Zou, Harry Becker, Frédéric Moynier, James M.D. Day, Wen Zhang, Yuqi Qian, Long Xiao, Zhaochu Hu, Zhenbing She, Hejiu Hui, Xiang Wu, Yongsheng Liu
The Moon’s mare volcanism predominantly occurs within the Procellarum KREEP Terrane (PKT), which is widely thought to be associated with KREEP components within the lunar interior. The Chang’e-5 (CE-5) mission sampled a young (2 Ga) mare basalt Em4/P58 unit of northern Oceanus Procellarum. The geochemistry of the CE-5 mare basalt enables assessment of mantle source compositions which are essential
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Recycling of crustal Os in nascent subduction zones revealed by ophiolitic boninites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-28 Wen-Jun Hu, Mei-Fu Zhou, Chao Li, John Malpas, Zhen-Chao Wang, Jun-Jie Xu
Olivine-rich lavas in the Margi area, Cyprus, are part of the boninitic Upper Pillow Lava series of the Troodos ophiolite. Re-Os isotope compositions of both whole rock and olivine phenocrysts of these lavas have been measured to determine the initial Os/Os isotope compositions of the primary boninitic magma. The Margi lavas have high and variable whole rock Re-Os isotope compositions (Re/Os: 1.060–8
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Characterising the decay of organic metal complexes in speleothem-forming cave waters Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-27 Sebastian N. Höpker, Sebastian F.M. Breitenbach, Megan Grainger, Claudine H. Stirling, Adam Hartland
Organic metal complexes (OMCs) transport trace metals (, Co, Ni, Cu) from surface soils, via the unsaturated zone, to sites of cave carbonate (speleothem) formation. OMCs clearly imprint on speleothem trace element chemistry, but the role of kinetic factors in the signal transfer process has yet to be elucidated. We investigated whether OMCs may viably link metal concentrations in stalagmites and local
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Trace elements in zircon record changing magmatic processes and the multi-stage build-up of Archean proto-continental crust Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-27 Nadja Drabon, Heather M. Kirkpatrick, Gary R. Byerly, Joseph L. Wooden
Zircon trace element geochemistry has become an increasingly popular tool to track crustal evolution through time. This has been especially important in early-Earth settings where most of the crust has been lost, but in some fortuitous instances detrital zircons derived from that lost crust have been preserved in younger sediments. To study the formation and geochemical evolution of continental crust
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Isotopic and kinetic constraints on methane origins in Icelandic hydrothermal fluids Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-27 Andri Stefánsson, Andrea Ricci, Mark Garnett, Jóhann Gunnarsson-Robin, Barbara I. Kleine-Marshall, Samuel W. Scott, Matteo Lelli, Carolina Dantas Cardoso, Raphaël Pik, Chiara Santinelli, Shuhei Ono, Peter H. Barry, Michael W. Broadley, David Byrne, Sæmundur A. Halldórsson, Jens Fiebig
The origin of methane in hydrothermal fluids has long been a subject of debate – whether it is abiotic or biotic. In this study, we aim to unravel and quantify the sources of CH in active hydrothermal systems by adopting a holistic approach analyzing well characterized high-temperature hydrothermal fluids (∼230–310 °C) in Iceland. We employ a broad variety of geochemical and isotope indicators, encompassing
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Origin of rare earth elements in acid mine drainage traced by strontium and neodymium isotopes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-27 Rafael León, Francisco Macías, Carlos R. Cánovas, Ricardo Millán-Becerro, Jonatan Romero-Matos, José Miguel Nieto
Acid mine drainage (AMD) generated from coal and sulfide mining has attracted much interest due to the high concentrations of rare earth elements (REE) observed. However, the origin of REE in AMD and particularly the mechanism of enrichment in medium REE remain uncertain. The combined study of Sr and Nd isotopes can be used to trace the processes that control the mobility and fractionation of REE in
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Mapping the redox state of the young Solar System using ytterbium valence state Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-27 Tahar Hammouda, Paul Frossard, Maud Boyet, Audrey Bouvier, Matthew Newville, Antonio Lanzirotti
We have determined the valence state of Ytterbium (Yb) in a collection of meteorites covering 4–5 orders of magnitude in oxygen fugacity (fO) by X-ray absorption near-edge structure (XANES) spectroscopy at the Yb L2 edge. In the studied meteorite minerals, Yb abundance was between 1 and 30 ppm. The data were obtained from merrillite grains (theoretical formula CaNaMg(PO)) from two equilibrated ordinary
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Ca isotopic gradients in epeiric marine carbonates: Diagenetic origins of and significance for Ca cycle reconstructions Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-26 C. Holmden, S.R. Kimmig, M.D. Nadeau
Marine carbonates record geochemical information on the state of Earth’s surface environment in the geological past, but recrystallization during burial can make the records difficult to interpret. Here, we report shore to basin gradients in δCa values in matrix limestone and burrow dolomite across a sequence of Late Ordovician (Katian Stage) burrow-mottled carbonates in the Williston Basin, an intracratonic
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Thermodynamic property estimations for aqueous primary, secondary, and tertiary alkylamines, benzylamines, and their corresponding aminiums across temperature and pressure are validated by measurements from experiments Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-22 Kirtland J. Robinson, Jeffrey S. Seewald, Sean P. Sylva, Kristopher M. Fecteau, Everett L. Shock
On Earth and beyond, organic chemistry often occurs in the presence of water within environments that deviate drastically from ambient conditions (25 °C and 1 bar). Accurately predicting aqueous organic reaction pathways is crucial toward understanding planetary scale processes such as the cycling of elements crucial for life (e.g., carbon and nitrogen). Advanced thermodynamic modeling can be utilized
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Mineral–water reactions in Earth’s mantle: Predictions from Born theory and ab initio molecular dynamics Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-21 Sarah J. Fowler, David M. Sherman, John P. Brodholt, Oliver T. Lord
Recent studies present compelling evidence that a free aqueous fluid phase exists within the upper mantle. Fluid may be present at depths as great as the transition zone (410–660 km) and possibly beyond. The chemical reactivity of such deep fluids can be predicted from the Born model of solvation. To use the Born model, we need to know the dielectric constant of water under mantle conditions. We have
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Partitioning of tin between mafic minerals, Fe-Ti oxides and silicate melts: Implications for tin enrichment in magmatic processes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-20 Chunxia Wei, Xiaolin Xiong, Jintuan Wang, Fangfang Huang, Mingdi Gao
The partition coefficients of Sn (tin) between minerals and silicate melts are vital for understanding the Sn enrichment during magmatic processes related to tin-granites. However, experimentally determined values remain scarce due to the difficulty in avoiding severe Sn loss to noble metal capsules. In this study, we performed mineral/melt Sn partitioning experiments at 0.5–1.0 GPa, 850–1000 °C, and
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Refining the roles of productivity, redox, and remineralization on the cadmium isotope composition of marine sediments Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-18 Logan A. Tegler, Sune G. Nielsen, Yi Wang, Florian Scholz, Jeremy D. Owens, Larry Peterson, Maureen Auro, Christopher W. Kinsley, Phoebe Lam, Tristan J. Horner
Cadmium (Cd) has a nutrient-like distribution in the ocean, similar to the macronutrient phosphate. Significant isotope fractionation induced by the biological cycling of Cd makes it a potential tracer for nutrients and productivity. However, the Cd flux and Cd isotope composition of marine sediments may also be influenced by local redox conditions and partial remineralization of organically hosted
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Effect of terrestrial weathering on stable Sr and Ba isotope compositions of eucrites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-16 Chang Nie, Jin-Ting Kang, Yun Jiang, Si-Jie Wang, Fang Huang, Wei-Biao Hsu
Stable strontium and barium isotopes are potential tracers for understanding planetary differentiation and the nature of the building blocks of terrestrial planets. Strontium and barium are fluid-mobile elements, but it remains unclear how terrestrial weathering affects the Sr-Ba isotopes compositions in achondrites, thus hampering the utility of Sr-Ba isotopes in cosmochemistry. In this study, we
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Dissolved rare earth elements in the North Pacific Subtropical Gyre: Lithogenic sources and water mass mixing control Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-15 Axiang Cao, Qian Liu, Jing Zhang, Alan M. Shiller, Yihua Cai, Ruifeng Zhang, Melissa Gilbert, Xianghui Guo, Zhiyu Liu
In the North Pacific Subtropical Gyre, which is one of the largest oligotrophic regions, there is a lack of information regarding the sources and transport of trace metals through water mass mixing. Rare earth elements (REEs) are essential for tracing lithogenic sources and water mass transport. In this study, we present dissolved REE concentrations and the factors controlling their distributions in
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Influence of species and stand position on isotopic and molecular composition of leaf litter during degradation in an urban mangrove forest Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-15 Sarah Louise Robin, Claude Le Milbeau, Kapeliele Gututauava, Cyril Marchand
Understanding the diagenetic processes of organic matter (OM) within mangrove forests is essential to grasp ecosystem dynamics and exchanges with adjacent ecosystems. This study investigated the influence of urban runoff on leaf litter degradation in a New Caledonian mangrove forest, subjected to urban rainwater for over 50 years. Focusing on and , our objectives were to determine factors affecting
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Temperature-controlled Se-S isotope fractionation during seawater mixing and sulfide precipitation in black smoker chimneys Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-15 Anna Grosche, Manuel Keith, Reiner Klemd, Harald Strauss, Carolina Rosca, Stephan König
Submarine hydrothermal venting leads to the formation of black smoker chimneys with complex internal zoning. These emerge through mineral precipitation under changing fluid conditions caused by variable degrees of fluid-seawater mixing. This study explores the potential of selenium (Se) isotopes as a novel tool to understand the enrichment processes and identify the sources of chalcophile elements
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Fluid-metasomatized rocks with extremely low δ26Mg values in subducted oceanic lithosphere: Implications for mantle Mg isotope heterogeneity and the origin of low-δ26Mg magmas Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-13 Jia-Wei Xiong, Yi-Xiang Chen, Marco Scambelluri, Xin-Yue Qiao, Yu Chen, Fang Huang, Donato Belmonte, Zi-Fu Zhao
The subduction of oceanic slabs with diverse lithologies greatly contributes to the geochemical heterogeneity of the mantle. Oceanic metasomatism leads to the formation of rocks with heterogeneous geochemical characteristics, which can be further modified by fluid–rock interactions during subduction zone processing. Investigations of exhumed high-pressure oceanic rocks not only shed light on the compositional
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Experimental and theoretical constraints on lithium isotope fractionation during brine evaporation and halite precipitation Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-12 Yongjie Lin, Marcello Merli, Paolo Censi, Simon A.T. Redfern, Yue Zhao, Qing-Zhu Yin, Mianping Zheng, Xudong Yu, Yongsheng Zhang, William J. Knapp, Edward T. Tipper
Marine evaporitic halite, precipitating from the advanced stage of extremely evaporated seawater, is the most common and abundant evaporitic mineral. The extent to which lithium (Li) is incorporated into evaporitic halite during geological periods of massive halite deposition, and the mechanisms of incorporation, are both unknown. These are each important, however, for the quantification of the isotope
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Lithium isotope fractionation during submarine hydrothermal alteration processes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-11 Di Cai, Hebin Shao, Long-Fei Gou, Zhangdong Jin, Shouye Yang
River water and submarine hydrothermal fluids are the two primary sources of lithium (Li) input to the ocean. However, compared to well-documented weathering processes, the behavior of Li isotopes during hydrothermal alteration processes remains obscure. In this research, we investigated the Li isotopic compositions (δLi) of hydrothermally altered sediments from two IODP drilling cores (C0013 and C0014)
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Isotopic evolution of the inner solar system revealed by size-dependent oxygen isotopic variations in chondrules Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-11 Yves Marrocchi, Alizé Longeau, Rosa Lozano Goupil, Valentin Dijon, Gabriel Pinto, Julia Neukampf, Johan Villeneuve, Emmanuel Jacquet
The systematic isotopic difference between refractory inclusions and chondrules, particularly for oxygen, has long indicated an isotopic evolution of the solar protoplanetary disk. However, it remains underconstrained whether such evolution continued during chondrule formation. Intrigued by past reports of the size-dependent oxygen isotopic compositions of chondrules in ordinary chondrites (OC), we
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Diagenesis of fossil gar fish scales with implications for geochronology and paleoenvironmental applications Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-08 John Fink, Marissa M. Tremblay, Thomas S. Tobin, Lisa D. Stockli, Daniel F. Stockli, Ryan B. Ickert
Fossil scales from gar fish are made of bioapatite and are common in the continental sedimentary record from the Cretaceous to the present, prompting interest in using these fossil scales as geochemical archives. We investigated the diagenetic characteristics of the two different components of gar scales: ganoine, which has similarities to tooth enamel, and bone. We examined microscopic textural characteristics
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Chemical weathering along a one-million-year soil age gradient on the Galápagos Islands Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-08 Franz Zehetner, Martin H. Gerzabek, J.Gregory Shellnutt, Pei-Hao Chen, I Nyoman Candra, Kuo-Fang Huang, Der-Chuen Lee
The Galápagos archipelago, a chain of islands formed by hotspot-induced volcanism on the Nazca tectonic plate, exhibits pronounced gradients of rock age and climate. Here, we investigate chemical weathering along a soil chronosequence (1.5 to 1070 ka) and under humid vs. dry conditions. Our results show considerable loss of base cations already in the early to intermediate phases of weathering under
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Silica polymerization and nanocolloid nucleation and growth kinetics in aqueous solutions Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-08 Samuel Scott, Iwona M. Galeczka, Ingvi Gunnarsson, Stefán Arnórsson, Andri Stefánsson
Amorphous silica precipitation from aqueous solutions at low temperatures (<100 °C) involves the initial nucleation and growth of silica polymers followed by aggregation, cementation and recrystallization to form opaline silica. In this study, silica polymerization was studied at temperature 23–80 °C, pH 2.48–9.65, and ionic strength 0.01–0.53 mol kg. Measured changes in the concentration of monomeric
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Nitrogen isotope gradient on continental margins during the late Paleoproterozoic Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-07 Kento Motomura, Andrey Bekker, Wouter Bleeker, Minoru Ikehara, Takashi Sano, Carl Guilmette, Ying Lin, Shoichi Kiyokawa
The late Paleoproterozoic was a key period in the evolution of Earth’s surface environments and life. It is generally accepted that during the 2.43–2.06 Ga Great Oxidation Episode, the atmospheric oxygen level rose to an intermediate state (0.1% to 10% of the present atmospheric level) and the chemical composition of the oceans changed significantly. The paleontological record indicates that eukaryotes
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Calcium isotope fractionation during tropical weathering of granites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-06 Bei-Bei Chen, Yongsheng He, Jinlong Ma, Yang Wang, Ze-Ning Wang, Gangjian Wei
Calcium (Ca) is a highly soluble and mobile element during silicate weathering, and its isotopes could be a promising tracer for continental weathering processes. However, it remains controversial whether Ca isotopes fractionate during granitoids’ weathering. Here we investigated Ca isotope fractionation (measured by Ca) behaviours on the weathering profile of the late middle Jurassic Fogang granite
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Nitrogen inventory of iron meteorite parent bodies constrained by nitrogen partitioning between Fe-rich solid and liquid alloys Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-06 Debjeet Pathak, Rajdeep Dasgupta
Delivery of nitrogen (N), one of the most important elements for life, to Earth thought to have occurred via both undifferentiated and differentiated bodies, lasting at least 50–100 Ma from the birth of the Solar System. Therefore, to understand how Earth got its N, it is imperative to know the N budget of the earliest formed bodies in our Solar System. The best astromaterials available for providing
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Cation exchange to montmorillonite induces selective adsorption of amino acids Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-04 Emily Millman, Anamika Chatterjee, Kimberly M. Parker, Jeffrey G. Catalano
Concentrating simple organic molecules, such as amino acids, in the adsorbed phase could have been an early step in prebiotic evolution towards more complex bio-macromolecules on the early Earth. Smectite clay minerals represent potential selective sorbents for prebiotic molecules because of their negative structural charge and high surface area. This study evaluated the adsorption behavior of amino
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Molecular transformation of petroleum compounds by hydroxyl radicals produced upon oxidation of reduced nontronite Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-04 Yuan Liu, Yahe Zhang, Guo Chen, Yang Li, Qiang Zeng, Jinglong Hu, Dafu Hu, Hailiang Dong
At redox interfaces, the interaction between oxygen and structural Fe(II) in minerals produces hydroxyl radicals (●OH); however, the specific reactivity and mechanisms of oxidation of complex petroleum compounds by ●OH remain poorly understood. This study investigates the interaction mechanisms between ●OH generated from reduced nontronite, an Fe-rich clay mineral (NAu-2), and petroleum compounds by
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Iron projectile fractionation processes in siliceous glass from small impact craters Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-02 Aaron J. Cavosie, Phil A. Bland, Noreen J. Evans, Kai Rankenburg, Malcolm P. Roberts, Luigi Folco
Detection of extra-terrestrial geochemical components in melt generated during meteorite impact provides diagnostic evidence that can be used to confirm a hypervelocity impact event, and in some cases, classify the projectile. However, projectile contamination is often present at sub-percent levels, and can be difficult to detect. In contrast, meteoritic abundances in glass from small impact craters
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Calcium isotope variability among ocean islands reveals the physical and lithological controls on mantle partial melting Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-03-01 Zachary T. Eriksen, Stein B. Jacobsen, James M.D. Day, William M. White
Major geodynamic processes, including mantle convection and plate tectonics, govern the exchange of mass between Earth's interior and its surface. These processes drive mass-transfer mechanisms such as partial melting and crustal recycling, which have generated a lithologically and compositionally heterogeneous mantle over time. Ocean island basalts (OIB) directly sample these heterogeneities, making
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Correlated IR-SEM-TEM studies of three different grains from Ryugu: From the initial material to post-accretional processes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-28 Alice Aléon-Toppani, Rosario Brunetto, Zélia Dionnet, Stefano Rubino, Donia Baklouti, François Brisset, Maxime Vallet, Eva Heripre, Tomoki Nakamura, Cateline Lantz, Zahia Djouadi, Ferenc Borondics, Christophe Sandt, David Troadec, Obadias Mivumbi, Megumi Matsumoto, Kana Amano, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana
In order to better constrain the alteration history of the Ryugu parent body, we performed a multi-analytical study combining scanning electron microscopy, transmission electron microscopy and infrared spectroscopy on sections extracted from the three fragments A0064-FO019, A0064-FO021 and C0002-FO019 returned from Ryugu by the Hayabusa2 space mission. The three sections show large differences in terms
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Isotope fractionation of alkaline and alkaline-earth elements (Li, K, Rb, Mg, Ca, Sr, Ba) during diffusion in aqueous solutions Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-25 Weiqiang Li, Zhihan Ji, Xianglong Luo, Yuqi Li
In this study, we used an improved “diffusion cell” method to precisely determine the diffusion-driven kinetic isotope fractionation factors of the Li, K, Rb, Mg, Ca, Sr, and Ba cations in aqueous solutions under room temperature. The obtained isotope fractionation factors (±2σ errors) are, α = 0.996139 ± 0.000140, α = 0.998572 ± 0.000072, α = 0.999333 ± 0.000020, α = 0.999877 ± 0.000010, α = 0.999704 ± 0
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Quantifying denudation rates and sediment recycling of low-relief, high-elevation landscapes using in-situ and meteoric cosmogenic nuclides Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-25 Ye Yang, Shun-Cheng Zhang, Jia-Xin Zhang, Li-Feng Cui, Cong-Qiang Liu, Sheng Xu
Quantifying Earth’s surface denudation rates is crucial for estimating sediment flux and its role in regulating global climate change. The inability of in-situ cosmogenic Be to quantify denudation rates in quartz–free environment has prompted the need for a new proxy–the ratio of meteoric Be to mineral-weathered Be in reactive phase (precipitated in or adsorbed onto secondary minerals). This study
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Comet 81P/Wild 2 dust impactors of Stardust turnip-like tracks analogous to cluster IDPs Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-24 Mingming Zhang, Noël Chaumard, Céline Defouilloy, William O. Nachlas, Donald E. Brownlee, David J. Joswiak, Andrew J. Westphal, Zack Gainsforth, Kouki Kitajima, Noriko T. Kita
We measured oxygen isotope ratios of 16 silicate fragments from seven aerogel tracks (turnip-like type B tracks 77, 149, 172, 191, and 220; carrot-like type A tracks 22 and 175) of the comet 81P/Wild 2 collector from NASA’s Stardust mission using secondary ion mass spectrometry. Thirteen were prepared by ultramicrotomy; three from track 220 were prepared by sputtering resin blocks using a SIMS Kohler
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Redox cycling of straw-amended soil simultaneously increases iron oxide crystallinity and the content of highly disordered organo-iron(III) solids Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-22 Christian Mikutta, Max Niegisch, Aaron Thompson, Ricarda Behrens, Laura S. Schnee, Martin Hoppe, Reiner Dohrmann
Iron speciation in soils is influenced largely by its redox state, but the extent of and controls on Fe speciation during recurrent reduction and oxidation events are not fully understood. To investigate the effects of organic matter (OM) inputs and the frequency and duration of redox oscillations on soil Fe speciation, we conducted redox-oscillation experiments with topsoil from a Fluvisol mixed with
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Pulsating dissolution of crystalline matter: A surface-controlled process Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-18 Jonas Schabernack, Cornelius Fischer
Rate maps quantify the variability of surface rates during the dissolution of crystalline matter. Recently, highly spatially resolved rate maps revealed the existence of rhythmic pulses of the material flux from the crystal surface. The mechanism underpinning this behavior is not yet understood but the two potential influencing factors are surface-controlled or transport-controlled conditions that
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Thermal-gradient-induced isotope fractionation during CO2-O2 triple oxygen isotope exchange Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-18 Yu Wei, Hao Yan, Yongbo Peng, Shanyu Han, Huiming Bao
Triple oxygen isotope (Δ′O) analysis of CO or carbonate is increasingly applied in diverse fields in earth and environmental sciences. One of the widely-used analytical methods for Δ′O of CO is through Pt-catalyzed oxygen isotope exchange between CO and O. However, large inter-laboratory inconsistencies in oxygen isotope fractionation between the two gases have been reported, potentially hindering
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Petrogenesis of a new type of intrusive shergottite: olivine-gabbro Northwest Africa 13227 Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-16 S. Benaroya, J. Gross, P. Burger, M. Righter, T.J. Lapen, S. Eckley
Petrologic investigations of martian meteorite Northwest Africa (NWA) 13227 indicate it is an olivine-gabbroic shergottite, a relatively new shergottite group, which differs from previously described gabbroic shergottites due to relatively high quantities of olivine. NWA 13227 is comprised of phenocrystic, oscillatory-zoned pyroxene and olivine, set in a matrix of maskelynite, Fe-Cr-Ti oxides, phosphates
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Deep mantle cycle of chalcophile metals and sulfur in subducted oceanic crust Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-16 Zongqi Zou, Zaicong Wang, Yi-Gang Xu, Stephen Foley, Huai Cheng, Liang Ma, Xiang Wang, Kang Chen, Zhaochu Hu, Yongsheng Liu, Yanhong Liu
Understanding the subduction-driven recycling of economically important chalcophile metals (e.g., Cu, Au, Ag, and platinum-group elements, PGEs) and volatiles (e.g., sulfur) is critical for assessing models of ore formation. However, whether the sulfide remains stable in recycled altered oceanic crust (AOC) in the mantle is unclear, and the influence of AOC-derived metasomatic agents on the extraction
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The geochemical evolution of basalt Enhanced Rock Weathering systems quantified from a natural analogue Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-16 T. Linke, E.H. Oelkers, K. Dideriksen, S.C. Möckel, S. Nilabh, F. Grandia, S.R. Gislason
Substantial quantities of fine-grained basaltic dust have fallen on South Iceland soils over at least the past 3300 years, making this region an ideal natural analogue to define the long-term consequences of current Enhanced Rock Weathering efforts. A relatively pristine South Iceland Gleyic/Histic Andosol, 3 m in height, receiving approximately 1250 mm of rainfall annually was selected for this study
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Equilibrium Mg and K isotope fractionation between carnallite and saturated brine: Calibrations and applications Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-10 Zhiguang Xia, Yongjie Lin, Dongdong Li, Lars Reuning, Zhongya Hu, Chuan Liu, Jun Mu, Weiqiang Li
Evaporites are important sedimentary records of seawater history, and their Mg and K isotopic signatures could be used to constrain the evolution of surficial cycles of Mg and K on Earth. However, the lack of detailed understanding of the Mg and K isotopic behaviors during the precipitation of key evaporite minerals has impeded the applications of Mg and K isotopes in evaporites. In this study, we
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Water-driven evolution of hydrous boron-bearing silicate melts at high pressures up to 8 GPa: Implications for dynamic properties and boron isotope content in hydrous mantle melts Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-10 A Chim Lee, Sung Keun Lee
A prominent seismic weakening has suggested the potential presence of HO-bearing complex silicate melts in the Earth’s interiors. As boron is typically accompanied by the hydrous fluids and melts and may be transported into deep mantle, boron isotopic evolution enables us to trace the deep-water cycle. The impact of HO on the structures of boron-bearing magmas is essential to grasp the melting processes