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Influence of anions on the formation of a passivating Fe-rich interfacial layer during olivine dissolution Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-13 Vincenzo Ettore Alagia, Shilpa Mohanakumar, Michael Hendrikus Gerardus Duits, Frieder Mugele
To better understand the rate and mechanism of olivine dissolution under acidic conditions, we exposed mm-sized ‘Norwegian olivine’ pebbles to hydrochloric, nitric and sulfuric acid at 65 °C and varying pH, for up to 50 days and monitored the evolution of Mg, Fe, and Si concentrations as well as pH. The evolution of the surface of the pebbles was examined ex-situ with Confocal Raman microscopy, Scanning
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Kinetics of methanethiol oxidation by oxygen under aqueous conditions Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-13 Irina Zweig, Alexey Kamyshny Jr.
Methanethiol is one of the most abundant volatile organic sulfur compounds in natural aquatic systems and one of the main products of dimethylsulfoniopropionate decomposition. This study focuses on the kinetic parameters of the reaction of methanethiol and its deprotonated form, methanethiolate, with dissolved oxygen in aqueous solutions at various reactant concentrations, pH, and temperatures. The
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Seawater intrusion causes substantial release of dissolved organic carbon in coastal paddy soils Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-13 Wenting Chi, Yang Yang, Pei Wang, Chao Guo, Zebin Hong, Shiwen Hu, Kuan Cheng, Shan Wang, Han Li, Qi Wang, Ying Li, Yang Wu, Yibing Ma, Tongxu Liu
Paddy soils located in coastal areas are readily exposed to seawater intrusion; however, the impact of salt ions on the adsorption of dissolved organic carbon (OCDissolved) at the soil–water interface and the transformation of solid-phase soil organic carbon (SOC) fractions remains quantitatively underexplored. Therefore, we investigated the dynamics of SOC, greenhouse gases (CH4 and CO2), and soil
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Copper isotopes in mare basalts reveal metal-silicate equilibration in the lunar magma ocean Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-13 G. Florin, P. Gleißner, H. Becker
In the last decade, several studies have reported enrichments of the heavy isotopes of moderately volatile elements in lunar mare basalts. However, the mechanisms controlling the isotope fractionation are still debated and may differ for elements with variable geochemical behaviour. Here, we present a new comprehensive dataset of mass-dependent copper isotope compositions (δ65Cu) of 30 mare basalts
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Does greater molecular diversity in soil organic matter imply greater persistence: Insights from molecular and multi-property analyses in Western China Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-12 Shanyi Tian, Sihua Zhu, Joeri Kaal, Jitao Lv, Rong Huang, Tongwen Zhang, Xiaolei Su, Yongguang Yin, Tao Jiang, Dingyong Wang
Chemodiversity of soil organic matter (SOM) is vital for its formation and eco-functions. However, the link between SOM molecular diversity and its persistence across various ecosystems remains unclear. This study investigates the correlation between SOM molecular diversity and persistence in cropland, grassland, and forest ecosystems in western China. We analyzed soil samples and identified 42 parameters
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Corrigendum to “Benthic deposition and burial of total mercury and methylmercury estimated using thorium isotopes in the high-latitude North Atlantic” [Geochim. et Cosmochimica Acta, 399 (2025) 191–204] Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-10 Xiangming Shi, Amber L. Annett, Rhiannon L. Jones, Rob Middag, Robert P. Mason
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Effects of mineralogy on Δ47 and Δ48 of carbonate-derived CO2 below analytical resolution Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-08 Miguel Bernecker, Magali Bonifacie, Philip Staudigel, Niels Meijer, Julien Siebert, Nicolas Wehr, Eiken Haussühl, Stefano M. Bernasconi, Daniel A. Petrash, Martin Dietzel, Jens Fiebig
Due to the lack of direct methods capable of determining the abundance of isotopologues containing multiple heavy isotopes within the crystal lattice, carbonates are typically reacted with phosphoric acid to produce CO2 analyte for clumped isotope analyses. This reaction is associated with fractionations of both bulk oxygen and clumped isotopes. Accurate knowledge of the effect of cation substitution
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Fast CO2 uptake by intense weathering of volcanic islands during interglacial stages Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-04 Francisco Hevia-Cruz, Anthony Hildenbrand, Nathan D. Sheldon, François Chabaux, Fernando O. Marques, Julie Carlut
The weathering of basaltic rocks, especially on volcanic islands, plays a crucial role in global carbon cycling. Intense precipitation and warm atmospheric conditions accelerate weathering processes in these environments. While most estimates of weathering rates derive from river chemistry, soils and paleosols remain underexplored. In this study, we investigated the geochemistry of paleosols developed
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Precambrian mantle metasomatism preserved by the Nd-Hf isotopic compositions of modern HIMU-type intraplate basalts Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-02 Leonie Sieger, Bradley J. Peters, Andrea Giuliani, Maria Schönbächler
The presence of HIMU (high-238U/204Pb) signatures in ocean island basalts has long been used to argue that ancient oceanic crust has been tectonically recycled into the mantle sources of plume-derived volcanic hotspots such as St. Helena or Mangaia. However, alternative hypotheses regarding the origins of HIMU signatures have also been put forward. This study addresses the origins of HIMU-like Pb isotopic
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Across-arc variations of potassium isotope compositions in a fluid-dominated subduction zone and implications for global potassium recycling Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-01 Ying-Yu Xue, Haiyang Liu, He Sun, Haiou Gu, Shichao An, Gerhard Wörner, Guozhi Xie, Maoqiang Yan, Dapeng Li, Yuxin Xiong, Fanfan Tian, Weidong Sun
To reveal the fluid variations in the mantle sources of arc lavas from a fluid-dominated subduction zone and to further constrain its implications for global potassium (K) recycling, we present the K isotope compositions of thirty-two arc lavas from a 220 km arc-front to back arc transect across the Kamchatka Peninsula. Our results show that arc lavas from Eastern Volcanic Front (EVF, −0.48 ± 0.02 ‰
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Co-evolution of organics and water in experimentally shocked Murchison and EET 90628 chondrites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-06-01 E. Quirico, H. Yabuta, P. Beck, L. Bonal, A. Bardyn, L.R. Nittler, C.M.O’D. Alexander
A significant population of primitive carbonaceous chondrites experienced short-duration heating, which is usually attributed to either impact or solar heating. Shock recovery experiments performed on carbonaceous chondrites have successfully reproduce the typical evolution in the petrographies and mineralogical compositions of natural samples. However, only few studies focused on the chemical and
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Shock deformation and U-Pb isotope systematics in zircon from impactites of the Rochechouart impact structure: Impact age and zircon provenance Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-31 Daniela Guerrero, Wolf Uwe Reimold, Natalia Hauser, Gavin Kenny, Martin Whitehouse, Philippe Lambert
The >23 km diameter, ∼207 Ma old Rochechouart impact structure is located in the NW part of the Paleozoic basement of the French Massif Central. Despite significant erosion, this impact structure preserves a heterogeneous suite of impactites, and the transition between the crater floor and the basement. Recent textural and geochronologic studies of U-Pb on zircon from impactites and basement lithologies
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Whole-rock Mg isotopes distinguishing high- and low-temperature S-type granites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-31 Yan Wang, Peng Gao, Zi-Fu Zhao, Hai-Ou Gu, Guo-Chao Sun, Hui-Chan Huang, Zhang-Jian Wu, Changqing Yin
Determining the temperature of crustal anatexis associated with granitic magmatism is vital for understanding the petrogenesis of granites and the processes underlying crustal anatexis. During the partial melting of metasedimentary rocks, the breakdown of biotite at elevated temperatures can lead to the formation of peritectic garnet, which is typically rare or absent at lower temperatures when melting
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Accretion of the anomalous CR2 chondrite Northwest Africa 14674: Implications for the complexities of the CR parent bodies Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-31 R.H. Hewins, P.-M. Zanetta, H. Leroux, S. Laforet, C. Le Guillou, M. Marinova, S. Pont, B. Zanda, R. Brunetto, J. Gattacceca, C. Sonzogni, L. Piani, Y. Marrocchi
An understanding of the differences between ungrouped, or anomalous, and normal carbonaceous chondrites could provide information on the population of parent bodies required to explain a chondrite group and on first solid accretion and evolution in the outer protoplanetary disk. The CR chondrites are key in this respect, as they display a unique formation history that distinguishes them from other
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Incorporation of fluoride in calcite: Insights from solid-state NMR, NanoSIMS, APT, HRSTEM and DFT calculations Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-30 Wei Li, Chao Ren, Kideok D. Kwon, Xiaolei Feng, Gang Sha, Jinhui Li, Sijia Dong, Xiancai Lu
Despite the abundant occurrence and large variation in fluorine (F) in calcium carbonate minerals in geological settings, it remains poorly understood to what degree F can be incorporated into calcium carbonate minerals. Particularly, molecular-scale evidence for F incorporation modes in the calcite structure is lacking. In this study, we conducted coprecipitation experiments for F with calcium carbonate
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Germanium isotope fractionation during evaporation from metal and sulfide melts: Implications for volatile element loss from planetary materials Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-30 Elias Wölfer, Christian J. Renggli, Christoph Burkhardt, Thorsten Kleine
The Ge elemental and isotopic composition of planetary materials holds essential clues on volatile element fractionation processes in nebular and planetary environments. To facilitate the interpretation of natural sample data we report the results of an experimental campaign that quantitatively assesses the elemental and isotopic fractionation of Ge during evaporation from graphite saturated Fe metal
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Contrasting Zn isotope fractionation effect during adsorption on micro- and nano-goethite Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-30 Zhao Wang, Michael F. Hochella Jr, Yiren Duan, Ganlin Zhang, Xiancai Lu, Wei Li
Goethite is essential in controlling Zn mobility and behavior in surface environments and can strongly influence Zn isotope fractionation through adsorption processes. However, the influence of particle size of goethite on stable isotopic fractionation remains poorly understood. This research investigates the fractionation of Zn stable isotopes during adsorption onto nano- and micro-goethite, focusing
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Of zircons and zircons: The tumultuous story of Zr-Hf and REE during cooling of peralkaline granites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-27 Loïs Monnier, Oscar Laurent, Stefano Salvi, Cyrielle Bernard, Mathieu Leisen, Guillaume Estrade, Philippe de Parseval, Claudie Josse, Armel Descamps-Mandine, Zhenpeng Duan, Sophie Gouy, Caliméria Passos do Carmo, Camille Dusséaux
Understanding the behavior of trace elements such as Zr-Hf, REE, and Th-U during magmatic and hydrothermal processes is crucial for unraveling the evolution of rare-metal peralkaline granites. These elements play key roles in geochemical cycles, mineral formation, and economic mineral deposits. The Evisa intrusion, a rare-metal peralkaline granite, is an ideal setting to study such processes due to
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From crustal protoliths to mantle garnet pyroxenites: insights from Os isotopes and highly siderophile elements Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-25 Alessandra Montanini, Ambre Luguet, David van Acken, Riccardo Tribuzio, Stephan Schuth, Geoff M. Nowell
Recycled pyroxenites are a key component of mantle heterogeneity, influencing magma generation and contributing to the radiogenic Os signature of oceanic basalts. However, natural examples of pyroxenites as proxies for crust-derived heterogeneities in the convective mantle are rare and recycling mechanisms remain debated. Here we report abundances of highly siderophile (HSE: Os, Ir, Pt, Pd, Re) and
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Systematics of helium diffusion sinks in apatite demonstrated by 4He/3He degassing experiments and modeling Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-25 Hongcheng Guo, Marissa M. Tremblay, Peter K. Zeitler, Bruce D. Idleman, Annia K. Fayon
Widely reported overdispersion of apatite (U-Th)/He ages has encouraged efforts to explore He diffusion kinetics and systematics in apatite. Studies such as continuous ramped heating (CRH) of apatite have revealed complex laboratory He behavior that is often correlated with abnormally old (U-Th)/He ages. Stemming from these studies is a hypothesis that diffusion sinks within apatite grains can reversibly
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Lithium- and oxygen-isotope compositions of a Si-rich nebular reservoir determined from chondrule constituents in the Sahara 97103 EH3 chondrite Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-25 Torii Douglas-Song, Tsutomu Ota, Masahiro Yamanaka, Hiroshi Kitagawa, Ryoji Tanaka, Christian Potiszil, Tak Kunihiro
Here we report the in situ ion-microprobe analyses of the Li- and O-isotope compositions of enstatite, FeO-rich pyroxene, olivine, glass, and cristobalite grains from six chondrule-related objects from the Sahara 97103 EH3 chondrite. The O-isotope composition of the enstatite grains scattered around the intersection between the terrestrial fractionation and primitive chondrule minerals lines. Whereas
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Oxygen-isotope variations in refractory inclusions from Rumuruti-type chondrites: Evidence for nebular gas heterogeneity and parent-body exchange Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-24 Samuel Ebert, Kazuhide Nagashima, Alexander N. Krot, Addi Bischoff
Refractory inclusions [Ca,Al-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs)] in unmetamorphosed chondrites (petrologic type ≤ 3.0) have typically uniform 16O-rich solar-like compositions. The origin of oxygen-isotope heterogeneity within individual refractory inclusions from weakly metamorphosed (petrologic type > 3.0) chondrites remains controversial. It may reflect (i) condensation
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Isotopic dynamics between methane-derived authigenic carbonates and gas hydrates: Insights from two deep-sea cold seeps Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-24 Josué J. Jautzy, Martine M. Savard, Stéphanie Larmagnat, Benjamin R. Fosu, D. Calvin Campbell
The use of clumped isotopes (Δ47) as a geothermometer in carbonates has become widespread in geosciences because carbonates are ubiquitous in the environment and this technique also constrains the precipitating fluid δ18O composition. However, in some contexts, Δ47 values cannot be used as a geothermometer. Instead, they provide insights into processes affecting the isotopic composition of CO2 and
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Rutile petrochronology and titanium isotope compositions record multiple melt-fluid-rock interactions in a continental subduction zone Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-24 Xiaojia Jiang, Xin Chen, Hans-Peter Schertl, Liam Hoare, Aitor Cambeses, David Hernández Uribe, Rongke Xu, Youye Zheng, Wen Zhang
Subduction zones act as pivotal engines for global element cycling. Titanium (Ti) isotopes, exhibiting mass-dependent fractionation, emerge as a robust geochemical tracer for deciphering complex processes in these dynamic settings. However, the behavior of Ti and its isotopes during metamorphic dehydration and partial melting of deeply subducted continental lithosphere remains poorly constrained. This
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The role of the melt aluminum saturation index in controlling gold and molybdenum proportions in porphyry copper deposits: An experimental investigation Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-23 Jianping Li, A.E. Williams-Jones, Xing Ding, Ziqi Jiang, Huayong Chen
Partition coefficients for Cu, Au and Mo between an aqueous fluid (∼ 4–16 wt% NaCl eq.) and felsic melts, were determined experimentally to better constrain the enrichment of these metals during magmatic fluid exsolution in porphyry copper systems. The experiments were conducted with a variety of melt and fluid compositions at 850 ℃, 200 MPa and an oxygen fugacity approximating that of the Ni-NiO buffer
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Path-integral molecular dynamics predictions of H isotope fractionation between brucite and water at elevated temperatures and pressures Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-23 Caihong Gao, Yun Liu
Hydrogen (H) isotope fractionation during the dehydration of H-bearing minerals is crucial for tracing the subduction processes. Previous studies have shown that H isotope fractionation between brucite and water is highly sensitive to the change of pressure. However, the detailed behaviors of H isotopes at high temperatures and high pressures remain poorly understood. In this study, we investigate
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Barium isotope variation during granitic magma differentiation: implications for the discrimination of crystal fractionation and fluid-magma interaction Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-23 Nian-Qin Zhang, Kun Zhou, Yi-Xiang Chen, Fang Huang, Xiao-Feng Gu, Lin-Hui Dong, Gengxin Deng, Peng Gao
The genesis and compositional diversity of granites are primarily controlled by multiple processes, including partial melting and magma differentiation. However, discriminating the individual effects of processes such as partial melting, fractional crystallization, and fluid-magma interaction on the evolution of granitic magma remains challenging. Barium isotopes serve as a potentially powerful tracer
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Modeling the controls on microbial iron and manganese reduction in methanic sediments Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-23 Racheli Neumann Wallheimer, Itay Halevy, Orit Sivan
Microbial iron and manganese respiration processes have been observed in deep methanic sediments of lacustrine and marine environments, challenging the “classical” model of microbial respiration in aquatic systems. Nonetheless, assessments of the type and relative role of these respiration processes in the methanic zone are lacking. Here, we quantify both the thermodynamic and the kinetic controls
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Boron isotopic and mineral chemical composition in greisen-related Li-Fe micas: Pathways and mechanisms for hydrothermal lithium enrichment Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-23 Dino Leopardi, Axel Gerdes, Richard Albert, Joachim Krause, Jens Gutzmer, Bernd Lehmann, Mathias Burisch
We present electron probe micro analyses (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) mineral chemistry and B-isotope data for magmatic and hydrothermal Li-Fe micas of the granite-related Sn-W-Li Sadisdorf greisen system in the Erzgebirge, Germany. These mineral-specific data were combined with novel in-situ mica and whole-rock powder-pellet LA-ICP multi-collector
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Reactive iron controls sulfur partitioning between pyrite and organic matter in sedimentary rocks Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-22 Hadar Cohen-Sadon, Yoav Oved Rosenberg, Simon Emmanuel, Shimon Feinstein, Alon Amrani
Sulfur isotopic values (δ34S) of pyrite and organic matter (OM) in sediments are widely used for the reconstruction of the sulfur and oxygen cycles as well as pathways of OM preservation. Currently, significant uncertainties persist regarding the mechanism by which sulfur is partitioned between pyrite and OM and its effect on the δ34S record of rocks. Here, we present experimental analysis of iron
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Shock metamorphic effects in phosphates from ordinary chondrites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-19 E. Dobrică, V. Megevand, A.N. Krot, A.J. Brearley
Studies of shock metamorphic effects in apatite and merrillite in nine ordinary chondrites (OCs) of petrologic types 3.5–6 and shock metamorphic stages S1–S5 using transmission electron microscopy (TEM) reveal a correlation between the extent of brittle deformation in phosphates and the shock metamorphic stage of six host meteorites. No correlation is observed in thermally annealed and partially melted
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Temperature-dependent modulation of the methylation degree of (tetra)ester-linked membrane-spanning lipids in an Acidobacterium Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-18 Yufei Chen, Huan Yang, Fengfeng Zheng, Ruijie Wu, Chuanlun Zhang, B. David A. Naafs, Richard D. Pancost, Zhirui Zeng
Ester-linked membrane-spanning lipids, such as iso-diabolic acid (iso-DA), are known components of some bacterial cell membranes, e.g., several species of Acidobacteria. However, the underlying biosynthetic mechanism and the physiological function of iso-DA remain elusive. In this study, we identified ester-linked membrane-spanning lipids, iso-diabolic-based tetraesters (iso-DTs) and their derivatives
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Self-organizational origin of oscillatory zoning in pyrite: A coupled diffusion–reaction model and pH-dependent As adsorption feedback mechanism Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-18 Wenhong Johnson Qiu, Mei-Fu Zhou
Pyrite from hydrothermal deposits often exhibits oscillatory zoning, controlling the distribution of trace elements, like As and Au. The origin of this zonal pattern has long been debated between episodic fluid changes and local chemical disequilibrium. Our study of an epithermal Pb-Zn deposit reveals arsenic oscillatory zonation in monocrystalline pyrite grains. Guided by the results of examination
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The molecular weight-dependent redox capacity of soil dissolved organic matter: Roles of aromaticity and organic sulfur Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-17 Jiang Xiao, Zhenqing Shi, Fu Liu, Qianting Ye, Lanlan Zhu, Quan Gao, Xin Yang, Paul G. Tratnyek
The redox capacities of soil DOM regulate the oxidation–reduction reactions by accepting or donating electrons, which influences a variety of critical redox processes such as greenhouse gas emissions and the (bio)geochemical cycle of contaminants. The composition and reactivity of DOM components vary with their molecular weight (MW), and, therefore, the redox capacities of soil DOM are expected to
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The link between seawater magnesium concentrations and anhydrite formation in the ocean crust Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-15 Angus Fotherby, Harold J. Bradbury, Benjamin Tutolo, Danielle Santiago Ramos, Eoin P. Walsh, Alexandra V. Turchyn
Subseafloor hydrothermal systems exert a strong control on the chemical composition of the ocean. Likewise, the chemical composition of the ocean impacts the chemical and physical reactions that happen during hydrothermal circulation, although this has been less well considered. We present a 2D model of basalt alteration under hydrothermal conditions, exploring how changes in major seawater ion concentration
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Transition from kinetic to equilibrium Zr isotope fractionations during magma crystallization Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-14 Zhen-Xin Li, Shao-Bing Zhang, Yong-Fei Zheng, Michael A. Antonelli, Wen Zhang, Liang Zhang, Fang-Yuan Sun, Ting Liang
Zirconium (Zr) isotopes are an emerging tool to study igneous processes. However, Zr isotope fractionation mechanisms are debated, especially regarding the relative roles of kinetic and equilibrium effects. Here, we report high-precision in-situ Zr isotope (δ94Zr) measurements in zircons from granitoids with ages of 3.4 to 2.5 Ga. The δ94Zr values in all magmatic zircons range from −0.63 to + 0.41 ‰
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Mineral phases and growth conditions of morphologically diverse shelfal ferromanganese concretions Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-12 Joonas Wasiljeff, Changxun Yu, Pasi Heikkilä, Yann Lahaye, Matti Kurhila, Wei‐Li Hong, Aivo Lepland, Sten Suuroja, Volker Liebetrau, Joonas J. Virtasalo
Ferromanganese concretions in the shelf sea regions, such as the Baltic Sea, are of significant interest due to their geochemical properties, economic resource potential, and roles in benthic ecosystems. This study analyses the authigenic and detrital mineral phases and their provenance in the Baltic Sea concretions, as well as their formation mechanisms and diagenetic evolution. These concretions
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The dual origin of granites from fluid-absent and fluid-fluxed melting of the juvenile lower crust: New constraints from Mo isotopes and phase equilibrium modeling Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-12 You-Shan Xia, Guo-Chao Sun, Peng Gao, Zi-Fu Zhao, Yao Zhou, Zhen-Xin Li, Gang Wen, Lei Qin
Water plays a pivotal role in the differentiation of continental crust and the formation of granitic magmas. However, it is still hotly debated how to identify fluid regimes during crustal anatexis. Molybdenum (Mo) isotopes have shown the potential to trace fluid activity during magmatic and metamorphic processes and thus are a valuable tool to identify the presence of free fluid during crustal anatexis
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Calcium isotope composition of the Gangdese continental arc deep crust and implications for making continental crust Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-11 Meiling Wang, Zaicong Wang, Liang Guo, Zongqi Zou, Fei Wu, Wei Dai, Jingliang Guo, Kang Chen, Lanping Feng, Haihong Chen, Ming Li, Yongsheng Liu
Magmatism in deep continental arcs is crucial for understanding the formation of andesitic continental crust. Garnet, pyroxene and amphibole are typical major mafic phases in deep arcs, with garnet potentially causing noticeable variations in stable isotopes of major elements such as Ca (δ44/40Ca). The upper continental crust (UCC) shows low δ44/40Ca value (0.70 ± 0.02 ‰, 2SE) relative to oceanic crust
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Structures and transport properties of Mg2SiO4-H2O system under high temperature and pressure: insights for supercritical fluids in deep subduction zones Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-11 Yifan Lu, Yicheng Sun, Guoxin Xia, Xiandong Liu, Guo-Guang Wang, Xiancai Lu
Understanding the structure and transport properties of supercritical fluids is crucial for gaining insights into their behavior in subduction zones. While previous research has provided an understanding of the properties of supercritical fluids derived from felsic melts, our knowledge regarding supercritical fluids formed from ultramafic melts in deep subduction zones remains limited. In this study
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Bioturbation and the effects on benthic flux of nitrogen in a large eutrophic lake: Insights from 224Ra/228Th disequilibrium and inverse geochemical modelling Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-11 Xiaoyan Shi, Guodong Chen, Rong Mao, Xin Luo, Jiu Jimmy Jiao, Meiqing Lu, Tianwei Wang, Wenli Hu, Xingxing Kuang
Benthic fluxes are critical pathways for constituent exchanges and biogeochemical interactions across sediment–water interface. To comprehensively evaluate the modulation of bioturbation on the benthic fluxes of nutrients, we present a novel inverse geochemical modelling framework in near-surface sediments of Lake Taihu, a highly eutrophic freshwater lake in eastern China. This approach incorporates
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Genesis of strongly peraluminous granites facilitates nitrogen retention in the crust Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-10 Yunzhe Chen, Jian Xu, Xiao-Ping Xia, Long Li
Sediments/sedimentary rocks are a major sink of atmospheric N2, which is mainly fixed into diazotrophic biomass and recycled into other organic matters or diagenetically transferred (in the form of NH4+) into the crystal structures of phyllosilicate minerals in sediments. Driven by tectonic activities, sedimentary rocks may experience various degrees of metamorphism with some eventually being melted
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Experimental degassing of moderately volatile chalcophile elements from silicate melt with and without sulfur present Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-09 William F. Heck, Achim D. Herrmann, Colin R.M. Jackson
We quantify the evaporation of moderately volatile chalcophile elements (MVCEs, here Cu, Zn, Ge, As, Ag, Cd, In, and Pb) from silicate melts. Our approach is to subject MVCE-bearing silicate melt to variable temperature (1480–1773 K), fO2 (10−9 to atmospheric) and fS2 (0 or 10−3 to 10−2), and duration (5 min to 24 h) using a gas-mixing furnace where evaporation can occur. Chemical analyses are completed
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Oxygen and hydrogen isotope compositions in dentine collagen correlate strongly with oxygen isotope compositions of enamel carbonate Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-09 L.M. Reynard, M.J. Kohn
The isotopic composition of tooth and bone has long been exploited in ecological, environmental, and archaeological studies. Increasingly, hydrogen and oxygen isotopes in collagen are used as tracers of environment and diet. However, the isotopic relationship between hydrogen and oxygen in collagen and oxygen in tooth enamel is poorly described. A new investigation of varied wild large herbivores shows
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The formation of the trinitites unveiled by their oxygen and silicon isotopic compositions Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-08 Nathan Asset, Marc Chaussidon, Christian Koeberl, Johan Villeneuve, François Robert
During the world’s first nuclear explosion, in 1945, glassy melts called “trinitites”, mostly derived from the sands at the surface of the test site, formed and were deposited at or near the hypocenter. The processes of formation of this fallout remain unclear. Here, we show how the oxygen and silicon isotopic compositions of three trinitites allow to refine their formation scenario. The three samples
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Compound class carbon isotope characterization of organic matter sources, transport, and degradation in sediments of large river-influenced coastal oceans Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-08 Fuqiang Wang, Shuwen Sun, Weikun Xu, Wenjing Fu, Honghua Shi, Meixun Zhao
The Yangtze River Estuary and the adjacent inner shelf are significant areas for both the burial and degradation of terrestrial organic matter (OM). However, the impact of hydrodynamics on the degradation of different types of organic compound classes has not been fully elucidated. This study measured dual carbon isotopes (δ13C, Δ14C) of organic compound classes [total hydrolysable amino acids (THAAs)
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Tin isotope systematics in subduction zones Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-07 Xueying Wang, Oliver Nebel, Alexandra Churchus, Peter A. Cawood
The origin of slab components in arc lavas remains controversial with proposed sources including direct sediment melts, sediment-mantle mélanges, or crustal fluids. Stable isotope distributions of fluid-borne metals and those immobile in subduction components have the potential to trace the respective contribution of these components if placed into the context of additional magmatic differentiation
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Combined Ca, Sr isotope and trace element analyses of Late Cretaceous dinosaur teeth: assessing diet versus diagenesis Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-06 Mateusz M. Michailow, Federico Lugli, Anna Cipriani, Francesco Della Giustina, Annalisa Ferretti, Daniele Malferrari, Denver Fowler, Elizabeth Freedman Fowler, Michael Weber, Thomas Tütken
The Sr and Ca isotope composition, along with trace element content in fossil teeth, provides valuable insights into biogenic and diagenetic processes. Identifying pristine biological signals is crucial for reconstructing the diet and trophic levels of extinct taxa. We present novel geochemical data from Tyrannosauridae and Ceratopsidae teeth of the Late Cretaceous, using radiogenic Sr (87Sr/86Sr)
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Large Zn isotope variations in lower oceanic crust offer insights into oceanic crustal magma plumbing system Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-06 Wei-Qi Zhang, Chuan-Zhou Liu, Zong-Qi Zou, Xiao-Ni Li
Constraining mid-ocean ridge magmatic processes is crucial for understanding the geochemical evolution of magmas traversing the oceanic crust. A crucial archive for investigating these magmatic processes is the chemical composition of lower oceanic crust. This study presents Zn isotope data for primitive to highly evolved cumulates from the Mid-Atlantic Ridge (Kane) and the Southwest Indian Ridge (IODP
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Coprecipitation of phosphate with calcite: Molecular-scale evidence for incorporation and inclusion mechanisms Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-06 Chao Ren, Yongfang Li, Shaofeng Wang, Jingzhao Wang, Junfeng Ji, Henry H. Teng, Brian L. Phillips, Kideok D. Kwon, Wei Li
Coprecipitation of phosphate in calcium carbonate minerals is a ubiquitous geochemical phenomenon in marine sedimentation and cave stalagmite formation, however, it is not clear whether phosphate is incorporated into the calcite structure. In this research, we applied solid-state nuclear magnetic resonance (NMR) spectroscopy to analyze P speciation during coprecipitation with calcite. The 31P NMR results
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238U/235U isotopic variations in angrites and their constituent minerals Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-05 Magdalena H. Huyskens, Yuri Amelin, Qing-Zhu Yin, Tsuyoshi Iizuka
Ages of angrites, a diverse and rapidly growing group of differentiated meteorites, are important for understanding the history of their parent body, which is proposed to be an archetypal first-generation planetesimal. Angrites also commonly serve as a time reference in the early Solar System chronology. Pb-isotopic ages of angrites can be determined with high precision, and the isotopic composition
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Corals feel the water chemistry: trace elements in coral skeletons reflect accurately their seawater chemistry, biological and geochemical implications Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-04 Sharon Ram, Jonathan Erez
The incorporation of trace and minor elements into coral skeletons and the underlying chemical and biological processes that govern them, are highly relevant for understanding coral biomineralization and for accurate reconstructions of past ocean conditions. In the present experimental study, that follows our previous publications (Ram and Erez, 2021, 2023), we determined the partition of six cations
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Strong depth-dependent chemical and structural characteristics of dissolved organic matter (DOM) in organic-rich sediment in a shallow temperate lake Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-04 Chenhui Wei, Shu Tao, Patrick G. Hatcher, Dongqiang Zhu
Porewater dissolved organic matter (DOM) in lake sediments is an important contributor to the global carbon cycle. The composition and structures of porewater DOM typically vary with depth, yet the variations in high-resolution depth intervals and the controlling biogeochemical processes are not well understood. Here we performed comprehensive, high-resolution (1 cm interval) characterization of sediment
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Thallium cycling and boundary exchange in a continental margin basin Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-04 Kasper P. Olesen, Sune G. Nielsen, Chadlin M. Ostrander, Nicol Udy, Donald E. Canfield
Thallium (Tl) isotopes are a robust tracer of ancient ocean oxygenation through their link to the burial flux of deep-sea manganese oxide minerals. Yet, the details of Tl geochemistry at the continental margin remain largely unexplored, hindering quantitative application of the palaeoredox proxy. To develop our understanding of Tl diagenesis, phase dynamics, and mass transfer at the continent-ocean
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Hydrogeochemical processes, reaction rates and effect of spatial scales in carbonate critical zone observatories: insights from the reactive-transport modeling of C-Q relations in four mountain watersheds Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-03 J. Ackerer, C. Legout, G. Nord, C.Le Bouteiller, L. Spadini, N. Hachgenei, B. Wild, O. Fischer, L. Jullien, J. Martins, C. Duwig, J. Gaillardet, I. Braud
This study investigates hydrogeochemical processes, reaction rates and the effect of spatial scales in mountain carbonate watersheds. A reactive-transport model was deployed to capture the concentration-discharge relations (C-Q relations) of major solute species measured in the river waters of two critical zone observatories located in the south of France (southern Alps and Ardèche). The specific control
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Fluid systems captured by giant amethyst-hosted fluid inclusions from continental flood basalts Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-03 Marta Sośnicka, Samuel Niedermann, Rudolph Erasmus, Sharad Master
Continental flood basalt (CFB) provinces, defined by the rapid emplacement of large volumes of mafic lava, represent some of the most significant large-scale magmatic events in Earth’s geological record. Gaining insight into the origin and evolution of fluid systems within these settings is critical for understanding the geodynamic architecture of large igneous provinces (LIPs) and accompanying mineralisation
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Chromite as a key player on highly siderophile elements and osmium isotope compositions of the refractory mantle Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-02 Ben-Xun Su, Ibrahim Uysal, Recep Melih Akmaz, Qi-Qi Pan, Yılmaz Demir, Lukáš Ackerman, Paul T. Robinson
Chromitites in ophiolites are recognized for their high concentrations of highly siderophile elements (HSE), notably IPGE (Os, Ir and Ru). However, the effects of this enrichment on ophiolitic rocks and mantle heterogeneity remain poorly understood and to address this issue, we investigated chromitites from the Pozantı-Karsantı and Kızıldağ ophiolites in Türkiye. The results reveal HSE enrichment,
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Microchemical and sulfur isotope variation in pyrite-marcasite: A proxy for low-temperature ore-forming processes in submarine hydrothermal systems Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-01 Xingwei Meng, Xiaohu Li, Basem Zoheir, Jianggu Lu, Xuegang Chen, Yanhui Dong, Jie Li, Fengyou Chu, Yongzhi Chu, Xianglong Jin
Pyrite-marcasite assemblages, formed at steep physicochemical gradients in submarine hydrothermal systems, serve as valuable records of fluid evolution and ore-forming processes. However, gaps remain in our understanding of the detailed pathways of pyrite-marcasite formation and their dynamics of trace element enrichment in seafloor massive sulfide deposits. Here, we utilize in-situ trace element and
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Benthic deposition and burial of total mercury and methylmercury estimated using thorium isotopes in the high-latitude North Atlantic Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-01 Xiangming Shi, Amber L. Annett, Rhiannon L. Jones, Rob Middag, Robert P. Mason
The high-latitude oceans are regions of high mercury (Hg) bioaccumulation, especially in the form of methylmercury (MeHg), which is of great concern in terms of human and ecosystem health. In the high-latitude North Atlantic (60-80°N), the deep water entrains the Hg-enriched Arctic water southwards, consequently influencing global Hg cycling. Whilst Hg removal has been proposed en route from the Arctic
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Colloidal association of selenite and selenate in water containing dissolved organic matter and ferric iron: implication for selenium mobility in the aquatic environments Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2025-05-01 Subhashree Dalai, Ashis Biswas
Dissolved organic matter (DOM)-modified organic and inorganic colloids are known to enhance the mobilization and transport of different trace elements in aquatic environments. Occurrences of selenium (Se) in natural waters often positively correlate with DOM under diverse environmental conditions, suggesting that DOM may enhance Se mobilization at the soil/sediment–water interface. Despite its importance