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Reply to “Artificially high stability of the sodium hydromolybdate ion pair in aqueous solution” by Gleb S. Pokrovski, Max Wilke and Maria A. Kokh Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-14 Qiushi Guan, Yuan Mei, Weihua Liu, Joël Brugger
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Understanding the extreme differentiation of granitic magmas through elemental geochemistry and Fe isotope signatures Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-14 Xiang-Long Luo, Chang-Zhi Wu, Jia-Xin She, Matthew J. Brzozowski, De-Hong Du, Shichao An, Weiqiang Li
The petrogenesis of extremely fractionated igneous rocks is closely linked to the evolution of the continental crust and the formation of rare metal mineralization. Extremely fractionated magmas evolve via fractional crystallization, hydrothermal evolution, and volatile-rich fluid–melt interaction, but the specific effects of these magmatic and magmatic–hydrothermal processes remain unclear. To understand
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Kinetics study on the temperature-dependent reduction of aqueous U(VI) by natural pyrite Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-14 Wujian Jin, Mingliang Kang, Yixiao Kang, Jingye She, Danwen Qin, Hanyu Wu, Kehang Wu, Chao Chen, Hai Liu
Previous studies have indicated that acid-washed pyrite is inert toward aqueous U(VI) under most pH conditions at ambient temperature, even though insoluble UO is the thermodynamically predicted product for the reduction of U(VI) by pyrite. Considering the exothermic nature of nuclear waste, the interaction between uranyl nitrate/acetate and natural pyrite was studied at temperatures ranging from 25 °C
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Barium-Mg isotopes in high Ba-Sr granites record a melt-metasomatized mantle source and crustal growth Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-06 Ren-Zhi Zhu, Mike Fowler, Fang Huang, Emilie Bruand, Xiao-Jun Wang, Li-Hui Chen, Craig Storey, Jiyuan Yin, Shaocong Lai
High Ba-Sr granites are geochemically distinct from the more familiar I-, S- and A-types (of igneous, sedimentary or anorogenic/anhydrous/alkaline parentage), in particular by their lack of depletion in Ba and Sr relative to other large-ion lithophile elements (LILE). These differences are sufficient enough to indicate different petrogenetic processes which are still the subject of considerable debate
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Zinc isotope fractionation during coprecipitation with amorphous iron (hydr)oxides Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-06 Yuhui Liu, Chengshuai Liu, Fei Wu, Yafei Xia, Meng Qi, Ting Gao
Coprecipitation facilitates the incorporation of Zn into the lattice of Fe (hydr)oxide, which is a crucial mechanism causing low Zn bioavailability in widespread Zn-deficient soils. Zn isotopes are a potential indicator of the coprecipitation of Zn and Fe (hydr)oxides in soils. However, the Zn isotope fractionation caused by coprecipitation with amorphous Fe (hydr)oxides (e.g., ferrihydrite) and the
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Iron isotope fractionation between metal and silicate during core-mantle differentiation in rocky bodies Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-05 Haiyang Luo, Lidunka Vočadlo, John Brodholt
Fe isotope variations in rocky bodies reveal fundamental information about planetary evolution. However, experimental results have come to contradictory conclusions on the equilibrium Fe isotope fractionation between metal and silicate during core-mantle differentiation. Many different processes, including evaporation, core formation, partial melting and disproportion of mantle silicate, have been
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Efficient gold scavenging by iron sulfide colloids in an epizonal orogenic gold deposit Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-02 Ya-Fei Wu, Katy Evans, Anthony E. Williams-Jones, Denis Fougerouse, Kirsten Rempel, Paul Guagliardo, Jian-Wei Li
Invisible gold hosted by pyrite represents a large proportion of gold resources worldwide. Gold is enriched in pyrite relative to hydrothermal fluids by five orders of magnitude, but controls on the hyperenrichment of gold in pyrite remain unclear. Here, we present the first micrometer- to nanometer-scale evidence for a colloidal iron sulfide phase that forms a precursor to pyrite and shows a remarkable
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The effect of fluorine on mineral-carbonatitic melt partitioning of trace elements – Implications for critical mineral deposits Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-02 Shuo Xue, Rajdeep Dasgupta, Ming-Xing Ling, Weidong Sun, Cin-Ty A. Lee
Natural carbonatite is associated with various types of deposits, including rare earth elements (REEs) and high-field strength elements (e.g., Nb). Although the spatial relationship between fluorine enrichment and the formation of carbonatite-type deposits is well-established, the underlying mechanism remains unclear. In this study, we investigate the influence of fluorine on the partitioning of trace
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Understanding microtektite formation: Potassium isotope evidence for condensation in a vapor plume Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-07-02 Piers Koefoed, Luigi Folco, Gianfranco Di Vincenzo, Nicole X. Nie, Billy P. Glass, Mason Neuman, Kun Wang
Tektite and microtektite formation have important implications on our understanding of impacts both on Earth, the Moon and on other bodies within our solar system. Here, we investigate the formation mechanisms of microtektites by analysing the K isotope systematics and elemental compositions of forty-four Australasian microtektites from various distances from the proposed impact location. Based on
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Dual clumped isotopes (Δ47 and Δ48) reveal non-equilibrium formation of freshwater cements Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-30 Chaojin Lu, Sean T. Murray, James Klaus, Donald F. McNeill, Peter K. Swart
Low-Mg calcite, precipitating from meteoric fluids, is a common mineral that forms in a variety of near-surface diagenetic environments. However, recent studies, based on a combination of analyses of δO and Δ values, have suggested that this mineral might form in disequilibrium and consequently yield kinetic bias in Δ-derived temperatures and fluid δO values. Here, we use dual clumped isotope proxies
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B(OH)4− and CO32− do not compete for incorporation into aragonite in synthetic precipitations at pHtotal 8.20 and 8.41 but do compete at pHtotal 8.59 Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-29 Cristina Castillo Alvarez, Kirsty Penkman, Roland Kröger, Adrian A. Finch, Matthieu Clog, Ed Hathorne, Nicola Allison
Coral skeletal B/Ca (effectively B/CO), in combination with boron isotopic composition (δB), has been used to reconstruct the dissolved inorganic carbon chemistry of coral calcification media and to explore the biomineralisation process and its response to ocean acidification. This approach assumes that B(OH), the B species incorporated into aragonite, competes with dissolved inorganic carbon species
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Impact-dispersed Fe–Fe1−xS core–shell particles in Chang’e-5 lunar soil impact glass Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-29 Chen Li, Yang Li, Kuixian Wei, Zhuang Guo, Rui Li, Xiongyao Li, Jianzhong Liu, Wenhui Ma
Lunar soil undergoes space weathering and accumulates optically active opaque particles (OAOpq) of different sizes, resulting in a darkening or red shift of the reflectance spectrum. The surfaces of weakly weathered objects exhibit spectral characteristics of strong weathering; these mechanisms are still unclear. The causes of OAOpq in lunar soil are complex, especially for submicrometer particles
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Complex zoning in the nakhlite and chassignite martian meteorites reveals multi-stage petrogenesis and undercooling during crystallization Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-28 Amanda Ostwald, Arya Udry, Juliane Gross, James M.D. Day, Sammy Griffin
Nakhlites (clinopyroxene-rich cumulates) and chassignites (dunites) are two types of meteorites that were emplaced onto — and subsequently ejected from— the surface of Mars together, but their petrogenetic history has been difficult to discern. We studied the primary magmatic history preserved in zoning patterns of cumulus phases from a suite of nakhlites and chassignites. Samples studied include nakhlites
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Evidence for large-scale, long-term highly siderophile element heterogeneities in the Atlantic mantle from Leg 153 and 209 peridotites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-28 Yin-Zheng Lin, James M.D. Day, Diana B. Brown, Jason Harvey, Chuan-Zhou Liu
Seafloor abyssal peridotites are products after partial melting and melt-rock interaction, providing constraints on upper mantle processes and heterogeneity. Despite extensive studies of ophiolitic peridotites and a burgeoning dataset for dredged abyssal peridotites, limited studies have been undertaken on abyssal peridotite drill core samples. This omission means a lack of comparison between modern
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Zircon Eu/Eu* in Archean TTGs with implications for the role of endogenic oxidation in Archean crustal differentiation Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-28 Ming Tang, Hao Chen, Shuguang Song, Guozheng Sun, Chao Wang
Redox condition is key to understanding crust formation and differentiation processes. We measured Eu anomalies in zircon in the Neoarchean tonalite-trondhjemite-granodiorite rocks (TTG) from the North China Craton to infer the Eu systematics in TTG melts, which allows us to constrain the minimum melt oxidation states. We find that those TTG samples formed at medium to high pressures have less Eu depletions
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Mercury from Icelandic geothermal activity: High enrichments in soils, low emissions to the atmosphere Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-28 Brock A. Edwards, Peter M. Outridge, Feiyue Wang
Geothermal activity is a natural source of mercury (Hg) to surface environments, but its contributions as part of the larger geogenic flux to the global Hg budget are poorly understood, in part due to large geographic gaps in emissions data where no measurements have been made. In this study we report the results of a field campaign over 2021 and 2022 on the highly active volcanic island country of
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Iron biogeochemical redox cycling dominantly controls cadmium availability in acidic paddy soils Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-27 Yang Yang, Tongxu Liu, Thomas Borch, Liping Fang, Shiwen Hu, Wenting Chi, Guojun Chen, Kuan Cheng, Qi Wang, Xiaomin Li, Xiu Yuan, Fangbai Li
Periodic redox condition changes in acidic paddy soils substantially induce the biogeochemical redox cycling, and consequently affect Cd availability. However, the underlying biogeochemical mechanisms of the complicated redox processes in paddy soil remain poorly understood. Thus, we investigated the dynamics of Cd fractions under anoxic (0–40 days) and oxic (40–55 days) conditions. The available Cd
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Melting experiments on Fe-S-O-C alloys at Martian core conditions: Possible structures in the O- and C-bearing core of Mars Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-26 Shunpei Yokoo, Kei Hirose
Recent seismological studies of the Martian core revealed its relatively low density, suggesting the presence of large amounts of light elements including oxygen and carbon in addition to sulfur. In order to reveal crystallizing solids in the light-element-rich core of Mars, we performed high-pressure melting experiments on Fe-S-O-C alloys at 26–49 GPa using a laser-heated diamond-anvil cell. The liquidus
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Degree of sector zoning in clinopyroxene records dynamic magma recharge and ascent Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-26 Alice MacDonald, Teresa Ubide, Silvio Mollo
The development of sector zoning in clinopyroxene is attributed to the influence of crystallisation kinetics imposed by magma undercooling () and may reflect variations in magma cooling histories. Yet, the degree of compositional variations between sectors has not been explored as a potential recorder of crystallisation dynamics. Here, we investigate the distribution of major, minor, and trace elements
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Toward mending the marine mass balance model for nickel: Experimentally determined isotope fractionation during Ni sorption to birnessite Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-25 Laura E. Wasylenki, Ryan M. Wells, Lev J. Spivak-Birndorf, Eva J. Baransky, Andrew J. Frierdich
In fewer than fifteen years, the study of Ni stable isotopes has advanced from early method development to application of a powerful tool for resolving a long-standing question: why does it appear that output fluxes of Ni from the global oceans far exceed input fluxes? The seawater concentration of Ni, a bioessential trace metal, is almost certainly at steady state on timescales comparable to its residence
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Pyrrhotites in asteroid 162173 Ryugu: Records of the initial changes on their surfaces with aqueous alteration Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-23 Hiroharu Yui, Shu-hei Urashima, Morihiko Onose, Mayu Morita, Shintaro Komatani, Izumi Nakai, Yoshinari Abe, Yasuko Terada, Hisashi Homma, Kazuko Motomura, Kiyohiro Ichida, Tetsuya Yokoyama, Kazuhide Nagashima, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew
The surface chemistry of pyrrhotites from intact particles directly collected from asteroid (162173) Ryugu was investigated by micro-Raman spectroscopy. The Raman peak characteristic to pyrrhotite was observed at around 115 cm in Ryugu pyrrhotites, similar to freshly cleaved surfaces of terrestrial pyrrhotites. Additional Raman bands centered at around 220, 275, and 313 cm with broadened features were
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Boron isotope pH calibration of a shallow dwelling benthic nummulitid foraminifera Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-23 Douglas Coenen, David Evans, Hagar Hauzer, Romi Nambiar, Hana Jurikova, Matthew Dumont, Puspita Kanna, James Rae, Jonathan Erez, Laura Cotton, Willem Renema, Wolfgang Müller
The boron isotope palaeo-pH/CO proxy is one of the key quantitative tools available to reconstruct past changes in the concentration of CO in the atmosphere. In particular, marine calcifying organisms have been shown to be useful archives of this proxy, enabling quantitative variations in pH/CO to be reconstructed throughout the Cenozoic. In order to provide an alternative proxy archive to the widely
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Magmatic sulfide oxidation drives crustal PGE mobilization: Implications for hydrothermal PGE mineralization Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-23 Zhenggang Li, James E. Mungall, Ariadni A. Georgatou, Hao Wang, Yanhui Dong, Guangyu Shi, Ling Chen, Fengyou Chu, Xiaohu Li
Platinum-group elements (PGEs) have a strong affinity for sulfur and tend to accumulate in the deep continental crust, either concentrated within magmatic Cu-Ni-PGE deposits or dispersed throughout disseminated sulfides. However, PGE enrichment in shallow magmatic-hydrothermal systems implies an obscure link to deep sulfide destabilization, which releases PGEs into ore-forming fluids. To bridge this
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The hidden link between dry ankaramitic melts and giant alkalic-type epithermal Au deposits: The Lihir Island example Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-23 Michael Schirra, Zoltan Zajacz, Daniel Müller
The magmatic controls on the formation of giant epithermal Au deposits genetically associated with alkaline magmatic systems are not well understood. The general model, which attributes the generation of alkaline magmas to low-degree partial melting of metasomatized lithospheric mantle in a post-subduction tectonic setting cannot easily explain why some of these magmas are highly fertile for Au mineralization
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Forging inner-disk Al-rich chondrules by interactions of CAI-like melt and ambient gas Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-22 Mingming Zhang, Kohei Fukuda, Michael J. Tappa, Guillaume Siron, William O. Nachlas, Makoto Kimura, Kouki Kitajima, Ann M. Bauer, Noriko T. Kita
The mechanism of gas-melt interactions and the compositions of precursors are key to understanding the formation of chondrules. To shed light on the two enigmas, we studied the petrography, chemistry, and oxygen isotopes of six Al-rich chondrules (ARCs, five glassy and one plagioclase-bearing) in unequilibrated ordinary chondrites (OCs, petrologic subtype: 3.05). The plagioclase-bearing ARC was also
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Role of natural isotopic fractionation in isotope geo- and cosmo-chronology: A theoretical investigation Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-22 Yankun Di, Qing-Zhu Yin, François L.H. Tissot, Yuri Amelin
We introduce a new isotope chronological model in which the natural mass-dependent isotopic fractionation effects of the radioactive (“parent”) and radiogenic (“daughter”) elements are systematically and rigorously considered. Using this model, we show that internally-normalized radiogenic isotopic ratios, commonly determined for daughter elements such as Sr, Nd, Cr, Ni, Hf, W, and Os, are dependent
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Diffusion, chemical bonding, and kinetic fractionation of noble gases in the primordial magma ocean Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-22 Adrien Saurety, Ozge Ozgurel, Chris Mohn, Razvan Caracas
Noble gases record in their radiogenic/non-radiogenic isotope ratios the traces of accretion history and degassing events from the early Earth, including giant impacts and the magma ocean stage, to large-scale recent volcanism. The diffusional behavior of noble gases in silicate magmas is one of the essential parameters needed to correctly model devolatilization from the magma ocean and subsequent
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Large magnesium isotopic fractionation in lunar agglutinatic glasses caused by impact-induced chemical diffusion Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-22 Le Zhang, Cheng-Yuan Wang, Hai-Yang Xian, Jintuan Wang, Yan-Qiang Zhang, Zhian Bao, Mang Lin, Yi-Gang Xu
Impact glasses are abundant in the lunar regolith, and Mg isotopes have the potential to trace components from various lunar crustal reservoirs, which have recently been shown to exhibit large Mg isotopic fractionations. However, it remains unclear whether Mg isotopic fractionation occurs during the formation of impact glasses. In this study, we report Mg isotopic and elemental compositional data for
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Elemental differentiation and isotopic fractionation during space weathering of Chang’E-5 lunar soil Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-22 Qingshang Shi, Yongsheng He, Jian-Ming Zhu, Yang Wang, Yang Wang, Hongjie Wu, Peijie Wang, Ruyi Yang, Aiying Sun, Yinchu Zhang, Guangliang Wu, Ruoqi Wan, Zhuo Lu, Fang-Zhen Teng, Chunlai Li, Wei Yang, Chi Zhang, Ziyan Han, Shan Ke
To investigate the chemical variation during space weathering of young mare basalts, here we report elemental, radiogenic Sr-Nd and stable Fe-Mg-Ca isotopic data of Chang’E-5 sieved soils and breccias. From the coarse fraction to the fine one, the sieved soils display increasing AlO (10.34 wt%–13.36 wt%) and Sr (248 ppm–307 ppm) but decreasing FeO (23.50 wt%–20.22 wt%), MgO (6.88 wt%–5.78 wt%), FeO/AlO
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Petrographic and chemical characterization and carbon and nitrogen isotopic compositions of cometary IDPs and their GEMS amorphous silicates Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-19 Birgit Schulz, Christian Vollmer, Jan Leitner, Lindsay P. Keller, Quentin M. Ramasse
GEMS (glass with embedded metal and sulfides) are the dominant carrier of amorphous silicates in anhydrous interplanetary dust particles (IDPs) and one of the most suitable materials to study early solar system processes. Amorphous silicates in 105 GEMS from eight IDPs were analyzed regarding texture and chemical composition to reassess GEMS formation theories and genetic relationships to amorphous
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The transport of bismuth in HCl-bearing aqueous vapour and low-density aqueous supercritical fluids: Implications for natural systems Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-19 Xin-Song Wang, A.E. Williams-Jones, Rui-Zhong Hu, Qi Liu, Fei-Xiang Liu, Yuan Mei, Zi-Qi Jiang, Lin-Bo Shang, Jing-Jing Zhu, Xian-Wu Bi
Hydration by HO clusters has been shown to be an important means of transporting metal complexes in hydrothermal vapours and low-density supercritical aqueous fluids. However, the effect of hydration on the transport of relatively volatile metal complexes such as those involving bismuth and chloride has not been evaluated. This effect is important to evaluate because bismuth is a key pathfinder element
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Source and fate of atmospheric iron supplied to the subarctic North Pacific traced by stable iron isotope ratios Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-18 Minako Kurisu, Kohei Sakata, Jun Nishioka, Hajime Obata, Tim M. Conway, Hannah R. Hunt, Matthias Sieber, Katsuhiko Suzuki, Teruhiko Kashiwabara, Sayuri Kubo, Makoto Takada, Yoshio Takahashi
The availability of dissolved iron (Fe) limits primary production over some regions of the surface ocean, especially in regions such as the subarctic North Pacific. In this work, we use Fe stable isotope ratios (δFe) in bulk and size-fractionated marine aerosol particles and dissolved Fe of surface seawater in the subarctic North Pacific on Japanese GEOTRACES cruise GP02 (Summer 2017) as a tracer to
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The thermal equation of state of xenon: Implications for noble gas incorporation in serpentine minerals and their transport to depth Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-15 A.D. Rosa, F. Zecchi, P. Condamine, M.A. Bouhifd, J.E.F.S. Rodrigues, E. Mijit, T. Irifune, O. Mathon, G. Garbarino, M. Mezouar, A. Dewaele, N. Ishimatsu
Isotopic signatures of heavy noble gases in the Earth's mantle contain a major component recycled by subduction. The experimental and field studies reported in the literature show increasing evidence that serpentine minerals can hold large quantities of noble gases, potentially serving as their primary vectors to depth. However, at present, their retention mechanism in these minerals is not fully understood
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Persistent organic alkalinity in the ocean Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-14 Chang-Ho Lee, Kitack Lee, Joon-Soo Lee, Kwang-Young Jeong, Young-Ho Ko
Ocean alkalinity (A) critically affects the buffering capacity and the precipitation and dissolution of calcium carbonate minerals in the ocean. However, our knowledge of A is still incomplete because of limited investigations into the contributions of dissolved organic matter (DOM) to alkalinity (A) across diverse ocean environments. Here, to improve the accuracy of seawater A measurements, we have
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Insights into stable strontium isotope fractionation in marine gypsum and its geochemical implications Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-14 Yana Kirichenko, Jörg D. Rickli, Tomaso R.R. Bontognali, Netta Shalev
The geochemical cycle of strontium is intimately linked to the long-term cycle of carbon, for instance, through their mutual involvement in continental weathering and marine carbonate sedimentation. Stable strontium isotopes (Sr) have recently emerged as a valuable tool, complementing radiogenic Sr isotope ratios (Sr/Sr), to further our understanding of the Sr cycle. Stable strontium isotopes are sensitive
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Reaction order of near equilibrium calcite dissolution: Uncertainties and ambiguities of isotopic tracer methods Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-14 Donald J. DePaolo, Shuo Zhang
Dissolution of calcite in water is fundamental to geochemistry. Laboratory methods generally give consistent dissolution rates under conditions far from equilibrium, but close to equilibrium the measurement of dissolution using isotopes is complicated by poorly understood calcite-fluid isotopic exchange processes. This near-equilibrium isotopic exchange occurs in laboratory experiments at rates of
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Identification of a primordial high D/H component in the matrix of unequilibrated ordinary chondrites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-14 Helen Grant, Romain Tartèse, Rhian Jones, Laurette Piani, Yves Marrocchi
Deuterium to hydrogen isotope ratios in unequilibrated ordinary chondrites (UOCs) which have undergone little-to-no thermal metamorphism pose an interesting problem when looking at water in the early Solar System. Bulk chondrite studies have shown that UOCs of the lowest subtypes have D/H ratios as high as comets from the outer Solar System, which, along with bulk UOC water abundances, decrease with
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Dual pathways of aragonite-to-calcite transformation in stalagmites: Implications for paleoclimate reconstructions Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-14 Rui Zhang, Haiwei Zhang, Christoph Spötl, Hai Cheng, Yanjun Cai, Carlos Pérez-Mejías, Xiyu Dong, Lijuan Sha, Youwei Li, Liangcheng Tan, Jingjie Zang, Xunlin Yang, Miaomiao Wang, Jiayu Lu, Youfeng Ning
Multiple geochemical proxies (e.g., trace elements, δO and δC) and precise Th ages in speleothems are crucial for conducting robust paleoclimatic reconstructions, but the impact of diagenesis on these proxies and Th ages is not well-established. In this study, we investigate the petrography and geochemical composition of six aragonite-calcite stalagmites from Shennong Cave in southeastern China to
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The primary abundance of chondrules in CI chondrites Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-14 Makoto Kimura, Motoo Ito, Akira Monoi, Akira Yamaguchi, Richard C. Greenwood
CI chondrites are the most significant extra-terrestrial samples for estimating the composition of primordial materials in the Solar System. However, CIs lose many primary features because of heavy parent body aqueous alteration. However, CI and CI-related Ryugu particles contain small amounts of relict anhydrous minerals, indicating primary occurrences of chondrules and refractory inclusions. In this
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Anthropogenic iodine-129 tracks iodine cycling in the Arctic Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-13 Yuanzhi Qi, Qiuyu Yang, Takeyasu Yamagata, Hiroyuki Matsuzaki, Hisao Nagai, Yuichiro Kumamoto, Motoyo Itoh
Global warming has accelerated the iodine cycle in the Arctic Ocean, amplifying its significance in the global iodine cycle. However, some intricacies of the iodine cycle in the Arctic marine environment remain unclear. In this study, we present concentrations of stable- and radio-iodine (I and I) in total iodine, iodide (I), and iodate (IO) in seawater from the Beaufort, Chukchi, and Bering Seas.
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Accretion of warm chondrules in weakly metamorphosed ordinary chondrites and their subsequent reprocessing Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-04 Alex M. Ruzicka, Richard C. Hugo, Jon M. Friedrich, Michael T. Ream
To better understand chondrite accretion and subsequent processes, the textures, crystallography, deformation, and compositions of some chondrite constituents in ten lithologies of different cluster texture strength were studied in seven weakly metamorphosed (Type 3) and variably shocked ordinary chondrites (Ragland—LL3 S1, Tieschitz—H/L3 S1, NWA 5421—LL3 S2, NWA 5205—LL3 S2, NWA 11905—LL3-5 S3, NWA
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Cycling of fluid-mobile elements through the forearc: Insights from the Cl, B, and Li isotope composition of Costa Rican spring fluids Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-06-02 Jacob P. Helper, Jaime D. Barnes, J. Maarten de Moor, Alejandro Rodríguez, Samuele Agostini, George Segee-Wright, Rudra Chatterjee, Daniel F. Stockli
Loss of slab-derived volatile and fluid-mobile elements (FME) through the forearc may represent a large, unaccounted for flux out of convergent margins. To address volatile recycling through the forearc and potential changes in fluid source from the progressively dehydrating subducting slab, we collected water samples from 44 different cold and thermal (>40 °C) springs on a transect across the outer
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Step propagation controls pore shape evolution when mineral walls dissolve under saturation gradients Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-31 Nathann Teixeira Rodrigues, Ismael S.S. Carrasco, Fábio D.A. Aarão Reis
We study the shape evolution of pores with calcite surfaces that dissolve with rates linearly varying along the pore length due to saturation gradients. A reaction–diffusion equation predicts that the walls have uniform slope along the pore length, which corresponds to walls with equally separated monolayer steps in a microscopic scale. We also study a nanoscale model that represents the detachment
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Arsenic-poor fluids promote strong As partitioning into pyrite Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-28 Martin Kutzschbach, Frederik Dunkel, Christof Kusebauch, Ferry Schiperski, Frederik Börner, Henrik Drake, Kevin Klimm, Manuel Keith
Pyrite is a ubiquitous sulfide mineral found in diverse geological settings and holds great significance in the formation of Au deposits as well as the safe utilization of groundwater due to its remarkable ability to incorporate substantial amounts of As. However, despite its importance, there remains a dearth of fundamental data on the partitioning of As between pyrite and fluid, which is key for
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Multiple sulfur isotopes evidence deep intra-slab transport of sulfate-rich fluids Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-26 Isabelle Genot, Samuel Angiboust, Pierre Cartigny
Sub-arc mantle oxidation is often attributed to sulfates from seawater transported in aqueous fluids derived from slab dehydration, but sulfur speciation and origin(s) in high-pressure fluids remain weakly constrained. Here, we use the four sulfur stable isotopes (S, S, S, S) to decipher processes, e.g. mixing of two end-member reservoirs and open-system reaction occurring during sulfur devolatilization
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Corrigendum to “Different metal coordination in sub- and super-critical fluids: Do molybdenum(VI) chloride complexes contribute to mass transfer in magmatic systems?” [Geochim. Cosmochim. Acta 354 (2023) 240–251] Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-25 Qiushi Guan, Yuan Mei, Weihua Liu, Joël Brugger
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Corrigendum to “Origin of carbonatite-related niobium deposits: Insights from pyrochlore geochemistry” [Geochim. Cosmochim. Acta 366 (2024) 1–16] Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-25 Felipe Velásquez-Ruiz, Martin Reich, Sam Broom-Fendley, Charles D. Beard, Fernando Barra, Rurik Romero, Pedro Cordeiro
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Lower crustal control in the iron isotope systematics of plutonic xenoliths from Adak Island, Central Aleutians, with implications for arc magma geochemistry Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-25 Emma S. Sosa, Claire E. Bucholz, Juan David Hernández-Montenegro, Michael A. Kipp, François L.H. Tissot, Barbara C. Ratschbacher, Jennifer M. Jackson, Suzanne Mahlburg Kay, Robert W. Kay
We present bulk-rock and mineral Fe isotope data of ultramafic to mafic xenoliths and basaltic to andesitic lavas from Adagdak Volcano (Adak Island, Central Aleutians) to study the effects of early differentiation on the Fe isotopic evolution of island arc basalts and their crystallization products. The Fe isotope composition of ultramafic cumulate xenoliths increases from dunite (δFe = –0.09 to –0
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Characterizing sulfur redox state and geochemical implications in deep-time using mineral chemistry network analysis Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-25 Eli K. Moore, Joseph E. Diedolf IV, Shaunna M. Morrison, Daniel R. Hummer
Sulfur (S) is a central element in global biogeochemical cycling and Earth’s redox evolution. Minerals that contain S are an important record of local environmental conditions at the time of their formation based on chemical speciation and redox. However, the oxidation state of S for hundreds of different S-containing minerals and thousands of S-containing mineral localities is unknown, largely sulfides
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Hydrological dynamics and manganese mineralization in the wake of the Sturtian glaciation Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-25 Yuntao Ye, Xiaomei Wang, Huajian Wang, Haifeng Fan, Zhigang Chen, Qingjun Guo, Ziteng Wang, Chaodong Wu, Donald E. Canfield, Shuichang Zhang
The Cryogenian Sturtian and Marinoan glaciations stand as the most extreme climate events in Earth history. Intriguingly, large-scale Mn carbonates characterize the nonglacial interlude of this period in South China. The formation mechanism of Mn carbonates and the potential correlation underlying this temporal association remain elusive. Here, we present an integrated petrographic and geochemical
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Uranium-series and strontium isotope systematics in soil carbonates from dryland Critical Zones: Implications for soil inorganic carbon storage and transformation Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-24 Syprose K. Nyachoti, Victor H. Garcia, Curtis Monger, Craig Tweedie, Thomas E. Gill, Lixin Jin, Lin Ma
Soil carbonates are dominantly present in dryland Critical Zone (CZ) and their formation could lead to important long-term carbon sequestration in arid to semiarid soils if the Ca ions were derived from silicate weathering or other non-carbonate sources. In managed CZ systems such as agricultural areas converted from natural drylands, irrigation has profound effects on the dryland CZ inorganic carbon
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A process-based geochemical framework for carbonate sediments during marine diagenesis Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-24 Mohammed S. Hashim, Stephen E. Kaczmarek, Gemakrisindo Wolfram Naa, David L. Bish, Adam V. Subhas
A significant proportion of marine calcium carbonate sediments are comprised of metastable minerals that are susceptible to diagenetic alterations during burial. These reactions can reset the geochemical signature of sediments and pore fluids and influence elemental cycling in the ocean. However, the timing and mechanisms by which these reactions take place are poorly constrained. This study uses cores
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Volatile budgets and gold mobilization in metasomatized sub-continental lithospheric mantle Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-23 Yanning Wang, Qingfei Wang, David I. Groves, Shengchao Xue, Tingyi Wang, Lin Yang, Jun Deng
Metasomatized sub-continental lithospheric mantle (SCLM) is increasingly proposed to control the formation of giant hydrothermal gold provinces. However, the key budgets for gold and volatile components in the SCLM under gold provinces remain poorly constrained, thus hindering definitive genetic models of gold metallogenesis. The Cenozoic hydrothermal orogenic gold deposits in the Ailaoshan gold belt
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Microbially-mediated reductive dissolution of Fe-bearing minerals during freeze-thaw cycles Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-19 Jinwook Kim, Young Kyu Park, Tae-hee Koo, Jaewoo Jung, Insung Kang, Kitae Kim, Hanbeom Park, Kyu-Cheul Yoo, Brad E. Rosenheim, Tim M. Conway
Constraining the role of microbes in the structural iron (Fe) reduction of iron-bearing minerals improves our understanding of sediments and ice sheets as a source of dissolved Fe (dFe) to the oceans. However, bio-mediated structural Fe-reduction has yet to be studied in cryospheric environments. Here, we show that the Fe reducing psychrophile bacterium isolated from sea ice in Antarctica, reduced
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Uranium(VI) hydrolysis up to 250 °C and its geological implications Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-18 Alexander Kalintsev, Artas Migdisov, Joël Brugger, Hongwu Xu
The hydrolysis of uranium(VI) has been investigated by solubility experiments conducted on sodium uranate (NaUO) over a pH range of 4.5–8 at 200 and 250 °C. Equilibrium constants for the , , and complexes have all been derived at both temperatures. Alongside this investigation a comprehensive literature review has been conducted to document previous investigations into U(VI) hydrolysis at temperatures
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Influence of structural Fe content in clay minerals on selenite redox reactions: Kinetics and structural transformations Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-17 Yanting Qian, Andreas C. Scheinost, Sylvain Grangeon, Alwina Hoving, Sergey V. Churakov, Maria Marques Fernandes
Redox reactions control the environmental fate of selenium, an element of concern due to its small gap between beneficial and detrimental effects on human health and due to the longevity of the radionuclide Se produced in nuclear reactors. Fe-bearing clay minerals are major redox-active ingredients of Earth’s critical zone and constitute an important component of the barrier in (radioactive and other)
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Nitrogen sequestration in the core at megabar pressure and implications for terrestrial accretion Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-16 Dongyang Huang, Julien Siebert, Paolo Sossi, Edith Kubik, Guillaume Avice, Motohiko Murakami
Nitrogen (N) is the most abundant element in Earth’s atmosphere, but is extremely depleted in the silicate Earth. However, it is not clear whether core sequestration or early atmospheric loss was responsible for this depletion. Here we study the effect of core formation on the inventory of nitrogen using laser-heated diamond anvil cells. We find that, due to the simultaneous dissolution of oxygen in
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Constraints on the source of Siberian Trap magmas from Mo isotope evidence Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-16 Aleksandr E. Marfin, Michael Bizimis, Peter C. Lightfoot, Gene Yogodzinski, Alexei Ivanov, Matthew Brzozowski, Anton Latyshev, Tatiyana Radomskaya
The relative contributions of asthenospheric mantle, lithospheric mantle, and continental crust in the genesis of the Siberian Traps Large Igneous Province (ST-LIP) remain poorly constrained. Most models invoke partial melting of asthenospheric mantle within a mantle plume with an inventory of recycled crustal material, with or without melting of subcontinental lithospheric mantle, and crustal contamination
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HED zircons as a window into the solar system’s first crust: Decoupling primordial differentiation, metamorphism and impact events through textural and chemical studies Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-14 Melanie Barboni, Madeline Marquardt, Nicholas E. Timms, Elizabeth Ann Bell
The study of Howardite-Eucrite-Diogenite (HED) meteorites provides unique insights into early planet formation and the impact events that shaped the early Solar System. However, unraveling the complex history of the HED parent body (hypothesized to be the asteroid 4 Vesta) from whole-rock samples is challenging since most HEDs are impact-related breccias comprising mixed lithic and mineral fragments
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Nitrogen isotopes as a robust tracer of fluid activities and mineral reactions in regional metamorphism Geochim. Cosmochim. Acta (IF 4.5) Pub Date : 2024-05-14 Yingzhou Li, Kan Li, Yunzhe Chen, Thomas Chacko, Thomas Stachel, Long Li
Regional metamorphism is characterized by complicated mineral-mineral reactions and fluid-mineral interactions, which may promote elemental migration and ore genesis. A robust tracer of metamorphic reactions and fluid activities is a key for identifying material sources and quantifying mass flow along metamorphic pathways. Here, through examinations of not only bulk-rock nitrogen (N) isotopic variation