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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 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 δCa) 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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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
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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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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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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
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The H-poor nature of incompletely melted planetesimals: The view from acapulcoites and lodranites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-10 Liam D. Peterson, Megan E. Newcombe, Conel M.O'D. Alexander, Jianhua Wang, Sune G. Nielsen
The abundance of H in planetary building blocks is of fundamental importance for constraining the evolution of the terrestrial planets. It is commonly assumed that chondrites are the principal sources of Earth’s H; however, recent studies have suggested that primitive achondrites and achondrites may retain a small complement of H. There are few constraints on the H budgets of primitive achondrites
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River-to-ocean pathways of beryllium-9 through estuaries Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-09 Chenyu Wang, Friedhelm von Blanckenburg, Ergang Lian, Shouye Yang, Jeffrey Paulo Perez, Hella Wittmann
Estuarine processes are key in modulating the riverine input of particle-reactive trace elements to the ocean. An important, but still under-utilized member of these elements is beryllium-9 (Be) that together with cosmogenic Be has been suggested to serve as a quantitative tracer of present and past continental weathering flux. This study investigates different pathways of terrigenous Be through coastal
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Ce and Eu anomalies in zircon as indicators of oxygen fugacity in subsolidus systems Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-07 Dustin Trail, Wriju Chowdhury, Nicholas D. Tailby, Michael R. Ackerson
Quantifying the oxygen fugacity (o) of high temperature lithospheric fluids, including hydrothermal systems, presents a challenge because these fluids are difficult to capture and measure in the same manner as quenched glasses of silicate melts. The chemical properties of fluids can however be inferred through mineral proxies that interacted with the fluids through precipitation or recrystallization
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BrGDGT lipids in cold regions reflect summer soil temperature and seasonal soil water chemistry Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-07 Jonathan H. Raberg, Sarah E. Crump, Greg de Wet, David J. Harning, Gifford H. Miller, Áslaug Geirsdóttir, Julio Sepúlveda
The distribution of brGDGT lipids produced by soil bacteria has been used to reconstruct temperatures in marine and terrestrial settings as far back as the Cretaceous period. However, modern calibrations of this proxy have primarily relied on air rather than in situ soil temperatures, which can differ by more than 10 °C. Furthermore, the influence of other parameters such as temperature seasonality
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Subducted serpentinite contributes to the formation of arc lavas with heavy Mo isotopic compositions Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-07 Fu-Qiang Dai, Yi-Xiang Chen, Ren-Xu Chen, Zi-Fu Zhao, Jie Li, Yu Wang
The petrogenesis of basaltic arc lavas with heavy Mo isotopic compositions is controversial. Given that oceanic crust preferentially loses isotopically heavy Mo during subduction at forearc depth and the remaining Mo is isotopically light and locked in rutile, fluids derived from such crust at subarc depth cannot account for the heavy Mo isotopic compositions of basaltic arc lavas. Serpentinites can
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Constraining the mass-dependent Ti isotope composition of the chondritic reservoir – An inter-laboratory comparison study Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-01 Merislava Anguelova, Nicolas Vilela, Sebastian Kommescher, Nicolas D. Greber, Manuela A. Fehr, Maria Schönbächler
Titanium isotopes are a promising tracer for planetary differentiation processes. The application of this tracer is, however, currently hampered by the lack of a robust estimate for the chondritic reservoir. Here, we conducted an inter-comparison Ti isotope study of three laboratories with the aim of providing an accurate and precise estimate for the chondritic reservoir. While previous estimates may
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Iron isotope fractionation during sulfide-promoted reductive dissolution of iron (oxyhydr)oxide minerals Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-03 Alison McAnena, Silke Severmann, Romain Guilbaud, Simon W. Poulton
Iron isotopes are a valuable tool for evaluating processes that control Fe redox cycling in modern and ancient environmental settings. However, robust evaluation of Fe isotope compositions in natural samples requires that fractionations associated with key (bio)geochemical reactions are well-defined. The reductive dissolution of Fe (oxyhydr)oxide minerals mediated by dissolved sulfide exerts a major
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Post-cumulus control on copper isotopic fractionation during oceanic intra-crustal magmatic differentiation Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-03 Wei-Qi Zhang, Chuan-Zhou Liu, C. Johan Lissenberg, Xiao-Ni Li
Unlike their eruptive counterparts, plutonic rocks often experience post-cumulus evolution prior to their final solidification. These processes have the potential to exert significant control on the distributions of elements and their isotopic compositions of plutonic rocks. However, our understanding in these effects remains limited, particularly for metal stable isotopes. Here, we carried out high-precision
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Role of the crystal chemistry on the dissolution kinetics of Fe(III)-rich smectites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-01 D. Masson, V. Robin, E. Joussein, E. Tertre, F. Baron
Smectites are reactive minerals that are present in surface environments. Most of the smectite dissolution kinetics reported in the literature are related to Al-rich smectites, whereas Fe(III)-rich smectites, which are commonly found in soils, have not been well studied. In this study, the impact of structural Fe(III) in smectites on the dissolution kinetics is determined under acidic conditions. The
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Equilibrium indium isotope fractionation between indium-bearing minerals: Insights from first-principles calculations Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-02-02 Haochen Duan, Fang Huang
Indium (In) is a critical element for electronics and catalysis industries and a volatile metal during planet accretion. Indium isotopes can be used to study cosmochemical and geochemical processes, but no equilibrium indium isotope fractionation factor is available, which restricts our knowledge of indium enrichment and incorporation during geological processes. Here, we investigate the reduced partition
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High CO2 in the mantle source of ocean island basanites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-26 Francesco Maria Lo Forte, Federica Schiavi, Estelle F. Rose-Koga, Silvio G. Rotolo, Maximilien Verdier-Paoletti, Alessandro Aiuppa, Vittorio Zanon
Some of the most CO2-rich magmas on Earth are erupted by intraplate ocean island volcanoes. Here, we characterise olivine-hosted melt inclusions from recent (< 10 ky) basanitic tephra erupted by Fogo, the only active volcano of the Cape Verde Archipelago in the eastern Atlantic Ocean. We determine H2O, S, Cl, F in glassy melt inclusions and recalculate the total (glass+shrinkage bubbles) CO2 budget
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Silicon isotopes in an Archaean migmatite confirm seawater silicification of TTG sources Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-24 Madeleine E. Murphy, Jane E. Macdonald, Sebastian Fischer, Nicholas J. Gardiner, Richard W. White, Paul S. Savage
Unraveling ancient melting processes is key to understanding how the earliest, tonalite-trondhjemite-granodiorite (TTG)-dominated continental crust formed from partial melting of amphibolite. Application of silicon isotope analysis to ancient crust reveals that Archaean TTGs exhibit consistently high Si isotope values (δ30Si) compared to modern granitoids, attributed to seawater-derived silica introduced
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Apportioning the molybdenum budget in shales to improve paleoenvironmental interpretations Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-28 Haolin Zhou, Mark A. Torres, Nicholas B. Harris, Gelu Costin, Tanguy Terlier
Molybdenum (Mo) abundance in marine shales/mudstones has been widely used to reconstruct depositional redox conditions. Prior laboratory experiments have observed Mo association with iron-sulfide and organic matter in the presence of aqueous H2S (euxinic conditions). The results of these experiments imply that sulfide minerals and organic matter are the primary hosts of Mo in the rock record, and this
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Apparent Isotope Effects of Reversible Enzymatic Reactions Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-26 Yuyang He, Martin Thullner, Rui Qin
Accurately predicting apparent isotope effects of biogeochemical processes can aid the interpretation of laboratory batch experiments and field observations. It has been observed that the apparent instantaneous isotope fractionation factor changes with residual substrate concentration during a reaction process. The change can be attributed to the reversibility of a biogeochemical reaction, which is
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Clumped isotope and Δ17O measurements of carbonates in CM carbonaceous chondrites: New insights into parent body thermal and fluid evolution Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-28 Matthieu Clog, Paula Lindgren, Sevasti Modestou, Alex McDonald, Andrew Tait, Terry Donnelly, Darren Mark, Martin Lee
The CM carbonaceous chondrites are key archives for understanding the earliest history of the solar system. Their C-complex asteroid parent body(ies) underwent aqueous alteration, among the products of which are carbonate minerals that can faithfully record the conditions of their formation. In this study we report carbon, triple oxygen and clumped isotope compositions of carbonates in six CM chondrites
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The response of riverine Mg isotope to hydrology and implications for continental weathering Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-28 Long Ma, Kang-Jun Huang, Pan Zhang, Zhangdong Jin, Yan Zhao, Yuanqiang Guo
The magnesium isotopic composition (δMg) of river water is a promising indicator of continental chemical weathering. While many studies have investigated the factors that influence riverine δMg, the impact of hydrology remains unclear. In this study, we collected eighty-four samples of stream water with nearly diurnal resolution in 2018 from a well-monitored, carbonate-rich catchment on the Chinese
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Diffusion of H-bearing species in anorthite-diopside glass below and across the glass transition Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-26 Thilo Bissbort, Hans-Werner Becker, Sumit Chakraborty
Diffusion of hydrogen (H) in silicate glasses plays a critical role in many applications because already at small concentrations the presence of H and its mobility have significant effects on the physical and chemical properties of materials. Although many of these applications such as weathering and alteration occur at low temperatures (e.g., < 600 °C), a quantification of diffusion rates at associated
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Transformation of vivianite in intertidal sediments with contrasting sulfide conditions Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-26 L. Joëlle Kubeneck, Luiza Notini, Katherine A. Rothwell, Giulia Fantappiè, Thomas Huthwelker, Laurel K. ThomasArrigo, Ruben Kretzschmar
Vivianite, a ferrous phosphate mineral, can be a significant phosphorus (P) burial phase in non-sulfidic, reducing coastal sediments. Expected sea level rise may increase sulfide production in currently non-sulfidic sediments containing vivianite, leading to conditions under which vivianite is thermodynamically unstable. Here, we compared the mineral transformation processes of two different vivianites:
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Sulfide compositions of young Chang’e-5 basalts and implications for sulfur isotopes in lunar basalt sources Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-24 Zaicong Wang, Yiheng Li, Wen Zhang, Qi He, Fabin Pan, Zhaochu Hu, Keqing Zong, Yantong Feng, Harry Becker, James M.D. Day, Wenlei Song, Hejiu Hui, Frédéric Moynier, Yun Jiang, Xiaojing Zhang, Zhenbing She, Xiang Wu, Long Xiao, Lu Wang
Sulfides are accessory phases in lunar rocks but are important for understanding lunar interior processes as well as impacts on the lunar surface. Whether or not the lunar mantle had achieved sulfide saturation during magma ocean evolution and displays homogeneous sulfur isotopes remains under debate. The Chang’e-5 (CE-5) mission returned young (2.0 Ga) basalts from a mare terrain in the northern Oceanus
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Shock features in carbonates from CM carbonaceous chondrites Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-22 E. Dobrica, K.A. McCain, A.J. Brearley
We have investigated different carbonate minerals (calcite, aragonite, and ankerite) from two meteorites with different shock metamorphic stages (Boriskino, CM2 − ∼S3-S4 and Murchison CM2.5-2.2 − S1-S2) using various electron microscope techniques. Our detailed transmission electron microscopy study shows that carbonates are valuable recorders of the shock metamorphic environment and help interpret
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Dissolved carbon dynamics and exchange in a high permeability beach aquifer Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-21 Yan Zhang, Yifan Guo, Junjian Wang, Damien T. Maher, Xiaolong Geng, Qianqian Wang, Kai Xiao, Hu Ding, Hailong Li, Chunmiao Zheng, Zhenyan Wang, Xuejing Wang
The biogeochemical transformation of dissolved carbon in tidal beaches affects the coastal carbon cycle and budget. Yet, the influence of groundwater flow on the behavior of dissolved carbon and CO2 flux across the different interfaces in these dynamic beach systems remains poorly understood, especially in deep beach aquifers. In this study, we investigated the biogeochemical reactions and origins
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Variations in isoprenoid tetraether lipids through the water column of the Western Pacific Ocean: Implications for sedimentary TEX86 records Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-22 Jinqiang Guo, Zongyue Wang, Eric P. Achterberg, Huamao Yuan, Jinming Song, Yuning Wang, Xuegang Li, Liqin Duan, Baoxiao Qu
The TetraEther indeX of 86 carbon atoms (TEX86) is widely used as a proxy to reconstruct past sea surface temperatures. Most current applications of TEX86 are primarily based on analyzing the composition of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) that comprise TEX86 in sediments, with the assumption that the sedimentary isoGDGTs are mainly derived from the surface mixed layer. Here
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Tracing DUPAL anomaly evolution in the Tethyan-Indian oceanic mantle Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-22 Chao Wang, Shuguang Song, Guochun Zhao, Mark B. Allen, Li Su, Lukáš Ackerman, Jiří Sláma, Donghai Zhang, Tao Wen, Di Feng, Ladislav Strnad
It is well established that Indian- and Pacific-type mantle domains observed in the present-day upper mantle are both long-lived and can be traced back to at least the Early Paleozoic, with their contrasting isotopic compositions inherited from mantle beneath the Tethys and Panthalassic oceans, respectively. But, the long-term evolution of the Tethyan-Indian oceanic mantle remains loosely constrained
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Electrochemical/computational analysis and the derivation of Pourbaix diagrams of redox-active structural and adsorbed species in uranyl peroxide clusters (U60) Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-21 Benjamin B. Gebarski, Udo Becker
Electrochemical analysis of U60 nanoclusters (Li40K20[UO2(O2)(OH)]60(H2O)214) and their natural analog, the mineral studtite (UO2)O2(H2O)2·(H2O)2, was carried out using cyclic voltammetry with a powder microelectrode setup. Voltammetric analysis was supplemented by ab initio quantum mechanical modeling to understand the mechanism, thermodynamics, and structural changes during redox transition (with
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Lithium isotopes in water and regolith in a deep weathering profile reveal imbalances in Critical Zone fluxes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-18 Di Cai, Michael J. Henehan, David Uhlig, Friedhelm von Blanckenburg
To trace Critical Zone processes and to quantify Li fluxes from one Critical Zone compartment into another, we investigated the Li concentration and isotopic composition (δLi) of time-series water samples (including subsurface flow, groundwater and creek water), vegetation, bedrock (including separated minerals from bedrock), and regolith (including exchangeable fraction and clay-sized fraction of
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Fractionation of iron and titanium isotopes by ilmenite and the isotopic compositions of lunar magma ocean cumulates Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-12 Kelsey B. Prissel, Michael J. Krawczynski, Nicole X. Nie, Nicolas Dauphas, Sarah M. Aarons, Andy W. Heard, Michael Y. Hu, E. Ercan Alp, Jiyong Zhao
Basaltic volcanism on the Moon produced low- and high-Ti mare basalt suites that are also distinct with respect to their iron, titanium, and magnesium isotopic compositions. Here, the equilibrium fractionation of Fe and Ti isotopes between ilmenite and melt was experimentally investigated in order to evaluate the role of ilmenite in generating the isotopic compositional variability among the lunar
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Acceptance of the 2021 Alfred E. Treibs Award by Stuart Wakeham Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-12 Stuart Wakeham
Abstract not available
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Productivity and organic carbon loading control uranium isotope behavior in ancient reducing settings: Implications for the paleoredox proxy Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-12 Randolph L. Rutledge, Geoffrey J. Gilleaudeau, Mariano N. Remírez, Alan J. Kaufman, Timothy W. Lyons, Steven Bates, Thomas J. Algeo
Uranium isotopes in ancient sedimentary rocks have emerged as a powerful proxy for the oxygenation history of Earth surface environments. Proper quantitative interpretation of δ238U data hinges, however, on an understanding of isotopic fractionation associated with uranium removal to sediments under different redox conditions. Whereas oxygenated environments are plentiful in the modern ocean, euxinic
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Citation for the 2021 Alfred E. Treibs Award to Stuart Wakeham Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-12 Elizabeth A. Canuel
Abstract not available
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Tungsten stable isotope composition of the upper continental crust Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-12 Sarah E. Mazza, Richard M. Gaschnig, Roberta L. Rudnick, Thorsten Kleine
Tungsten (W) stable isotope data for twenty-four composites made from the fine-grained matrix of glacial diamictites, deposited between the Mesoarchean and the Paleozoic, as well as two Archean tonalite-trondhjemite-granodiorites (TTG) are used to refine the W isotope compositions (expressed as δ186W deviations from the NIST 3163 W standard) of the upper continental crust (UCC). To do this we evaluate
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A volatile sulfur sink aids in reconciling the sulfur isotope mass balance of closed basin lakes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-12 Antoine Crémière, Christopher J. Tino, Maxwell E. Pommer, Xingqian Cui, Matthew Roychowdhury, Roger E. Summons, Alex Sessions, J. Fredrick Sarg, Timothy W. Lyons, Jess F. Adkins
Sedimentary rocks from the early Eocene Green River Formation comprise the largest known lacustrine oil shale deposits, contain remarkably well-preserved fossils, and provide a unique record of climate evolution across the Early Eocene Climate Optimum, a period of high atmospheric CO. The depositional environment of these intermountain lakes spanned from relatively fresh and fluvially influenced to
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Surface ocean biogeochemistry and deep ocean circulation control relationships between nutrient-type trace metals (Cd, Ni, Cu, and Zn) and nutrients in the South Atlantic Ocean near the subtropical front Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-08 Xue-Gang Chen, Martha Gledhill, Maeve C. Lohan, Angela Milne, Eric P. Achterberg
The ocean region along the latitude of 40oS in the South Atlantic, characterized by enhanced primary productivity, forms a transition zone between the nutrient replete but iron depleted Southern Ocean, and the nitrate and iron depleted Subtropical Gyre. Here, we present distributions of nutrient-type dissolved and particulate trace metals (dTMs and pTMs) including cadmium (Cd), nickel (Ni), copper
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Potassium isotopes as a tracer of hydrothermal alteration in ore systems Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-07 Kun-Feng Qiu, Rolf L. Romer, Zheng-Yu Long, Hao-Cheng Yu, Simon Turner, Ruo-Qi Wan, Xiao-Qiang Li, Zi-Yue Gao, Jun Deng
Hydrothermal alteration is crucial in the formation of many ore deposits, with potassium (K) mobilization and cycling being prevalent. Potassic metasomatism of wall rocks generally forms K-bearing minerals, such as hydrothermal feldspar and mica. However, determining the source and redistribution of K (and other elements transported by the same fluid) in hydrothermal systems is challenging. K isotopes
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A dolomite-based record of seawater calcium isotope composition over the Neogene Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-07 Xiao-Feng Liu, Xiao-Ming Liu, Shikui Zhai, Zhaofeng Zhang, Dongjie Bi, Xi-Kai Wang, Cheng Cao, Xinyu Liu
The calcium isotope composition of seawater (δ44/40Casw) records important information on the evolution of the calcium and carbon cycles over geologic time. Over the past two decades, many attempts have been made to reconstruct the Neogene δ44/40Casw variation using various calcium isotope records of seawater or seawater-like pore fluids. Nonetheless, large discrepancies still exist among these Neogene
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Compositional Analysis of Apollo 12 Granitic Breccia 12013: Insights into Protoliths and Formation Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-04 S.N. Valencia, R.L. Korotev, B.L. Jolliff
We report bulk rock composition and mineral chemistry of previously unstudied fragments and thin sections of lunar granitic breccia 12013. Instrumental Neutron Activation Analysis data on 25 fragments indicate that the 12013 breccia can be described as a three-component system comprising granitic, rare earth element (REE)-rich, and mafic components. The granitic component is low in FeO and REE but
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Lipid composition, caloric content, and novel oxidation products from microbial communities within seasonal pack ice cores Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2024-01-05 Henry C. Holm, Helen F. Fredricks, Shavonna M. Bent, Daniel P. Lowenstein, Kharis R. Schrage, Benjamin A.S. Van Mooy
Sea ice is a critical feature of polar environments with importance for coastal ecosystems. Along the West Antarctic Peninsula (WAP), climate change is causing decreases in seasonal sea ice duration and extent. Organic carbon within sea ice is an important aspect of southern ocean carbon cycling but less studied than water column or sedimentary carbon reservoirs. Though conditions within sea ice can
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Growing Diamonds in the Laboratory to investigate Growth, Dissolution, and Inclusions Formation processes Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2023-12-29 Hélène Bureau, Imène Estève, Caroline Raepsaet, Geeth Manthilake
Replicating lithospheric diamonds experimentally helps reveal their histories at depth, which may be complicated by successive growth and dissolution episodes. Here, we present diamond growth and dissolution experiments to constrain the conditions of diamond formation and residence in the Earth’s lithosphere before their transport to the surface. Experiments were performed on mixtures of carbonates
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Calcium isotopic compositions of eclogite melts and negligible modification during reaction with lithospheric mantle Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2023-12-30 Zongqi Zou, Zaicong Wang, Xiao-Jun Wang, Yi-Gang Xu, Li-Hui Chen, Meiling Wang, Lanping Feng, Ming Li, Yongsheng Liu
Subduction-driven recycling of crustal materials plays a substantial role in the generation of geochemical and lithological heterogeneities in the Earth’s mantle. Because the distinct compositions and/or mineral-specific equilibrium isotopic fractionation effects are present in eclogitized crustal materials, stable isotopes of major elements that exert significant impacts on geochemical and petrologic
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Sulfur geochemistry of the Salitre Formation phosphorites: Implications for the role of microbial ecology and sulfur cycling in phosphogenesis on an Ediacaran carbonate platform Geochim. Cosmochim. Acta (IF 5.0) Pub Date : 2023-12-30 Cecilia Sanders, Theodore Present, Selva Marroquin, John Grotzinger
The distribution and activity of polyphosphate-accumulating sulfide oxidizing bacteria within marine sediments control the spatial distribution of sedimentary phosphorite formation in the modern ocean. In modern phosphogenetic settings, the concerted effect of microbial sulfide oxidation and microbial sulfate reduction in sediment pore waters is preserved in the sulfur isotope composition of trace