Geochimica et Cosmochimica Acta最新文献

{"title":"Citation for Treibs award 2026 to Professor emeritus Steven John Rowland made by Associate Professor Maya Al Sid Cheikh (University of Edinburgh, Scotland)","authors":"","doi":"10.1016/j.gca.2026.08.008","DOIUrl":"https://doi.org/10.1016/j.gca.2026.08.008","url":null,"abstract":"","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"42 1","pages":""},"PeriodicalIF":5.0,"publicationDate":"2026-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148717645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystal defects drive gold remobilisation in arsenopyrite","authors":"Denis Fougerouse,&nbsp;Nicolas Thebaud,&nbsp;David W. Saxey,&nbsp;William D.A. Rickard,&nbsp;Laura Petrella,&nbsp;Siyu Hu,&nbsp;Tommaso Tacchetto,&nbsp;Laure Martin,&nbsp;Wess Edgar,&nbsp;Steven M. Reddy","doi":"10.1016/j.gca.2026.05.002","DOIUrl":"10.1016/j.gca.2026.05.002","url":null,"abstract":"<div><div>Arsenopyrite is a major host of refractory Au in ore deposits, and remobilisation of Au from this mineral has been proposed as a significant process leading to the formation of secondary native Au mineralisation. However, the processes for Au remobilisation in arsenopyrite remain poorly constrained. In this study, we apply state-of-the-art post-acquisition pattern matching algorithms to resolve artefacts associated with arsenopyrite pseudosymmetry. This approach improved data quality enabling robust crystallographic interpretations. By using a correlative approach including microstructural characterisation, geochemical, textural and nanoscale investigations from two orogenic Au deposits, we report two mechanisms for Au remobilisation, both controlled by dislocations. In the Obuasi Au deposit, arsenopyrite shows evidence of re-equilibration with a sharp reaction front between Au-rich and Au-poor arsenopyrite. Dislocations are systematically present in proximity to the front, suggesting that they act as fast diffusion pathways for mass exchange, instead of porosity as previously proposed. In the Fosterville Au deposit, a small amount of crystal-plastic deformation in arsenopyrite generated low-angle boundaries that are depleted in Au compared to undeformed arsenopyrite. Dislocations along the low-angle boundaries are enriched in trace elements such as Ni, but are depleted in Au, suggesting that the presence of dislocations may selectively remobilise Au. In summary, our results highlight the fundamental role of crystal defects in controlling Au remobilisation during coupled dissolution-reprecipitation and crystal-plastic deformation.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 213-224"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148541649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Substrate source and mineral protection synergistically govern the temperature response of lake sediment organic carbon","authors":"Beichen Wang,&nbsp;Xiaoxi Sun,&nbsp;Zhen Yang,&nbsp;Xinyi Li,&nbsp;Min Cai,&nbsp;Bingfu Yao,&nbsp;Li Liu,&nbsp;Tianran Sun,&nbsp;Jian Yang,&nbsp;Jibin Han,&nbsp;Xiying Zhang,&nbsp;Jianping Wang,&nbsp;Hongchen Jiang","doi":"10.1016/j.gca.2026.04.040","DOIUrl":"10.1016/j.gca.2026.04.040","url":null,"abstract":"<div><div>Lake sediments constitute a significant yet vulnerable component of the global carbon cycle. Nevertheless, the mechanisms controlling the temperature response of source-specific organic carbon (OC) remain unclear, limiting predictive capability of climate-carbon feedbacks. To address this, we investigated the decomposition of plant- and microbial-derived OC in Qinghai-Tibetan Plateau lake sediments via a 180-day microcosm incubation at 8 °C and 18 °C, integrating biomarker analysis, optical spectroscopy, and mass spectrometry. The results show that plant-derived OC forms the foundational component of the sediment OC pool, dominating total OC accumulation and exhibiting low temperature sensitivity, which facilitates its preservation under warming. In contrast, microbial-derived OC shows higher temperature sensitivity and is preferentially decomposed at elevated temperatures; its stability depends strongly on mineral protection, correlating positively with clay content, reactive calcium, and cation exchange capacity. We propose a synergistic framework wherein the substrate source establishes the baseline stability of sediment OC, while mineral protection modulates the temperature-sensitive microbial fraction. The overall OC response to warming is determined by the trade-off between these two mechanisms, implying a potentially diminishing climate-carbon feedback from lake ecosystems over time. This study provides a mechanistic basis for predicting OC fate in inland waters under warming.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 187-199"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148541751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraining deformation timing of orogenic systems by fluid inclusion 40Ar/39Ar geochronology of syn-kinematic tourmaline","authors":"Ming Xiao,&nbsp;Xiujuan Bai,&nbsp;Wanfeng Zhang,&nbsp;Huaning Qiu,&nbsp;Jérémie Soldner,&nbsp;Wenyong Duan,&nbsp;Ming Chen,&nbsp;Han Zheng,&nbsp;Kang Xu,&nbsp;Yang Wu,&nbsp;Guochun Zhao","doi":"10.1016/j.gca.2026.06.015","DOIUrl":"10.1016/j.gca.2026.06.015","url":null,"abstract":"<div><div>Dating discrete deformation events is essential for reconstructing orogenic histories but is often hindered by polyphase tectonism, thermal overprinting, and a lack of suitable geochronometers. This study evaluates the feasibility of applying ⁴⁰Ar/³⁹Ar geochronology to fluid inclusions within syn-kinematic tourmaline, a chemically and thermally robust borosilicate. We systematically compared ⁴⁰Ar/³⁹Ar stepwise crushing and step-heating on tourmaline from leucogranite dykes and quartz veins from the Chinese Altai, which formed during the Chinese Altai-Junggar arc convergence (termed D3 phase). Stepwise crushing on tourmaline samples oriented parallel to D3 fold axial planes, randomly oriented within syn-D3 leucogranite dykes, and occurring as undeformed crystals in late-D3 quartz veins, yielded ⁴⁰Ar/³⁹Ar ages of 322 Ma, 274 Ma, and 261 Ma, respectively, from their primary fluid inclusions. These ages, in line with the regional tectonic framework, tightly constrain the initiation, peak melting, and termination of D3 reworking. In contrast, conventional step-heating of tourmaline grains and crushed tourmaline powders can be compromised by contamination from non-radiogenic argon or by potential mixing with secondary sources, leading to geologically inconsistent results. Our findings validate the ⁴⁰Ar/³⁹Ar stepwise crushing of fluid inclusions within syn-kinematic tourmaline as a robust geochronological tool to date deformation time. Compared to accessory mineral U-Pb systems that reflect broader magmatic histories, the ⁴⁰Ar/³⁹Ar ages derived from tourmaline fluid inclusions prove to be more sensitive recorders of discrete deformation events. This approach overcomes the problems of excess argon and thermal resetting, offering a direct window into dating fluid-mediated deformation and deciphering the evolution of reworked crustal terranes.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 99-115"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148289449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of sulfur-iron redox systematics during mantle wedge metasomatism by slab fluids","authors":"Patrick Beaudry,&nbsp;Dimitri A. Sverjensky","doi":"10.1016/j.gca.2026.06.009","DOIUrl":"10.1016/j.gca.2026.06.009","url":null,"abstract":"<div><div>Chemical mass transfer in subduction zones is a fundamental aspect of plate tectonics on Earth, driving arc magmatism and the recycling of subducted materials to the surface. The reactive mechanisms between aqueous fluids released by slab dehydration and mantle minerals are not well understood, but are likely associated with the transfer of redox potential, which may explain the generally oxidized character of arc magmas. Here we use the Deep Earth Water (DEW) model to perform mass transfer calculations of sulfur-saturated slab fluids at variably oxidized conditions (FMQ + 1 to FMQ + 2) reacting with garnet lherzolite assemblages. Fe³⁺-bearing multi-component phases are considered in DEW calculations for the first time, including Fe-Ti-Cr-Mg-Al oxides (ilmenite and spinel solid solutions), as well as clinopyroxene (acmite, NaFe³⁺Si₂O₆; esseneite, CaFe³⁺AlSiO₆) and garnet (andradite, Ca₃Fe³⁺₂Si₃O₁₂) components. Fluid-rock reaction heating paths are calculated at fixed pressure (2 and 3 GPa) and temperature increasing from 650 to 950°C. At those subarc conditions, sulfate is very efficient at oxidizing iron and producing overall oxidized mineral products after reaction with the depleted mantle, whereas CO₂-rich fluids cause only marginal oxidation. Modeled Fe₂O₃ contents in spinel, clinopyroxene and garnet match those of natural data from variably metasomatized xenoliths. Modeled bulk rock Fe₂O₃ contents are also similar to those of oxidized arc xenoliths. Furthermore, despite oxidizing significant quantities of mantle iron, predicted fluids remain sulfate-rich owing to very high initial sulfur solubilities. This implies that mantle metasomatism with sulfur-rich, oxidized slab fluids could lead to arc magmas with sulfur budgets and isotopic compositions dominated by recycled subducted sulfur. We further show that our predicted concentrations of sulfur in slab fluids are generally consistent with the global fluxes of water and sulfur in and out of subduction zones.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 82-98"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148289475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A hybrid mantle source for Chang’E-5 basalt: insights from ultra-trace element ratios of olivine","authors":"Cheng-Yu Du,&nbsp;Shao-Bing Zhang,&nbsp;Hejiu Hui,&nbsp;Ting Liang,&nbsp;Wan-Cai Li,&nbsp;Yong-Fei Zheng","doi":"10.1016/j.gca.2026.05.006","DOIUrl":"10.1016/j.gca.2026.05.006","url":null,"abstract":"<div><div>China’s Chang’E-5 (CE-5) lunar mission retrieved the youngest known mare basalt with low magnesium number (Mg#) and high incompatible element contents. However, the nature of its mantle source remains debated. Here we carried out <em>in-situ</em> analyses of major and trace element contents in olivine and pyroxene for CE-5 basalt clasts to constrain the petrogenetic process and mantle source of CE-5 basalt. The results indicate that the pyroxene Ti# (molar Ti/(Ti + Cr)) rose sharply at an early stage into the high-Ti basalt field and subsequently remained constant, implying extensive fractional crystallization of the CE-5 basalt. The near constant Ti content in olivine records an early crystallization of ilmenite at an olivine Mg# of approximately 60. Calculated TiO₂ and Cr₂O₃ contents of the melt equilibrated with the most forsteritic olivine yielded TiO₂ content of 6.06 ± 0.77 wt% and Cr₂O₃ content of 0.516 ± 0.089 wt%. Pyroxene exhibits concurrent decreases in LREE/HREE ratios, Zr/Y ratio and Al content as its Mg# decreases, whereas the early decrease of olivine Zr/Y ratio indicates a primitive melt with high Zr/Y ratio. Integrating these findings with previously reported isotopic data, theoretical modelling supports a hybrid mantle source dominated by orthopyroxene cumulate, with a small proportion of ilmenite-bearing cumulate (IBC, 0.40–0.55%) and KREEP (0.11–0.15%). Such a source region supports a geodynamic mechanism for the young mare magmatism that the IBC-rich hot plume rises from the core-mantle boundary heating the upper mantle that contains small amounts of IBC and KREEP to melt.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 225-240"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148291666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of metasomatism on halogen distribution in the North American sub-continental lithospheric mantle","authors":"George Segee-Wright,&nbsp;John C. Lassiter,&nbsp;Jaime D. Barnes,&nbsp;Véronique Le Roux,&nbsp;Brian D. Monteleone,&nbsp;Matthew K. Riley","doi":"10.1016/j.gca.2026.04.042","DOIUrl":"10.1016/j.gca.2026.04.042","url":null,"abstract":"<div><div>Fluorine (F) and chlorine (Cl) in the mantle are useful tracers of subduction processes. Recent work has suggested that F and Cl can be sequestered in the Sub-Continental Lithospheric Mantle (SCLM) through interactions with subduction- or mantle-derived fluids and melts. Yet, the distribution of metasomatic halogens in the SCLM is unclear. In this study, we examine the effects of metasomatism and melt depletion on the halogen abundances in nominally anhydrous minerals (NAMs; olivine, orthopyroxene, and clinopyroxene), as well as in hydrous minerals (antigorite, chlorite, amphibole) in variably metasomatized SCLM peridotite xenoliths from the Colorado Plateau (USA) and the southern Rio Grande Rift (USA). We find that F and Cl are dominantly hosted in hydrous minerals in modally hydrated xenoliths, but H₂O and Cl are variably enriched in NAMs resulting from recent metasomatism via a Cl-rich fluid. Fluorine shows no such enrichment in NAMs, likely due to the F-poor nature of the fluid in this region. In modally anhydrous xenoliths, Cl hosted in NAMs show no correlations with indices of metasomatism. Instead, the majority of Cl and variable amounts of other incompatible trace elements are likely hosted along grain boundaries, resulting from metasomatic enrichment of the SCLM. Grain boundaries may be an important host of metasomatic Cl in the modally anhydrous SCLM, potentially altering the calculated quantity of Cl in global SCLM and impacting the extent of Cl released during intraplate magmatism.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 200-212"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148541750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heavy tungsten isotopes in sulfidic seep sediments linked to carbonate precipitation","authors":"Xiaoming Miao,&nbsp;Jiangong Wei,&nbsp;Davide Oppo,&nbsp;Xiting Liu,&nbsp;Jingrui Li,&nbsp;Hangyu Nan,&nbsp;Xi Yu,&nbsp;Ziyao Fang,&nbsp;Zhiwei He,&nbsp;Jiangtao Li,&nbsp;Hongxiang Guan,&nbsp;Nengyou Wu,&nbsp;Thomas J. Algeo","doi":"10.1016/j.gca.2026.04.033","DOIUrl":"10.1016/j.gca.2026.04.033","url":null,"abstract":"<div><div>Tungsten isotopes (δ¹⁸⁶/¹⁸⁴W) are a promising proxy for reconstructing the evolution of marine redox conditions over geological time. Conventional understanding posits that under sulfidic conditions – in contrast to oxic environments – tungsten predominantly remains in dissolved form within seawater. Consequently, marine sulfidic sediments are thought to lack authigenic W enrichment and to typically display isotopic signatures comparable to upper continental crustal values. Here, we present new <em>δ</em>^186/184W data from sulfidic methane-seep sediments at the Haima Cold Seep (South China Sea) that reveal unexpectedly elevated isotopic compositions (to +0.43‰). These markedly heavy W isotopic signatures contrast with the near-homogeneous values documented in other sulfidic marine environments, including Black Sea sapropels (+0.05‰ to +0.07‰) and globally distributed analogues. The positive correlations between carbonate content, <em>δ</em>^186/184W, and W enrichment factor are indicative of authigenic carbonate precipitation as the principal control on the W isotopic compositions of sediments in these systems. Methane-derived carbonates exhibit particularly heavy <em>δ</em>^186/184W values (+0.40‰ to +0.48‰), supporting this hypothesis and unequivocally identifying such carbonates as a significant sink for heavy W isotopes. These findings demonstrate that some sulfidic sediments host authigenic W burial, and highlight the role of carbonate phases as an archive for reconstructing marine redox evolution. Our results further extend the utility of W isotopes as a proxy for paleoenvironmental reconstruction.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 289-300"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148542124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal monitoring of serpentinization in peridotite: mineral replacement, volume change and hydrogen production","authors":"Zhao Xia,&nbsp;D.Nicolas Espinoza,&nbsp;Carl Steefel,&nbsp;Michael Manga,&nbsp;Mengsu Hu","doi":"10.1016/j.gca.2026.04.029","DOIUrl":"10.1016/j.gca.2026.04.029","url":null,"abstract":"<div><div>The growing demand for hydrogen necessitates innovative production strategies beyond conventional fossil fuel-derived methods. Stimulated geologic hydrogen generation through serpentinization of ultramafic rock is a promising alternative. However, the feedback mechanisms between fluid transport, mineral reactions, and rock deformation that govern the kinetics and evolution of serpentinization remain poorly constrained. This study investigates hydrogen yields and mineral phase transformations during laboratory serpentinization of peridotite. Experiments conducted at 90 °C and 0.1 MPa, and 200 °C and 6 MPa, show hydrogen yields of 0.5 to 0.9 μmol/g rock and 20.8 to 31.2 μmol/g rock after 30 days, respectively. High-resolution X-ray computed tomography captures the spatiotemporal (4D) evolution of serpentine vein networks during serpentinization, revealing serpentine growth primarily along pre-existing veins and sustaining fluid-mineral interactions through submicron vein permeability. Quantitative volume analyses show that serpentine volume fraction increases by 6.7 ± 0.93 to 10.2 ± 1.42 vol% from an initial value of 38 to 39 vol%, resulting in a volumetric strain of + 0.005 ± 0.00025 to + 0.006 ± 0.00012 (positive for volume increase) under zero effective stress. These results indicate that serpentine vein growth during serpentinization is primarily driven by mineral replacement at olivine-serpentine interfaces rather than by stress-induced fracturing followed by mineral infill, with fluid transport playing an important role in reaction progression. Overall, the findings highlight serpentinization as a coupled hydro-thermo-chemo-mechanical process that can occur over short timescales and at relatively low temperatures in peridotite, features that are desirable for scalable geologic hydrogen stimulation and production.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 116-130"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148542157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early diagenetic alteration of sediment porewater in Indian Ocean basins and its controls on rare earth elements enrichment","authors":"Fangyu Shen,&nbsp;Li Li,&nbsp;Xuefa Shi,&nbsp;Xiaojing Wang,&nbsp;Mu Huang,&nbsp;Hongna Liu,&nbsp;Miao Yu,&nbsp;Dongjie Bi,&nbsp;Jihua Liu","doi":"10.1016/j.gca.2026.04.006","DOIUrl":"10.1016/j.gca.2026.04.006","url":null,"abstract":"<div><div>Rare earth elements and Yttrium (REY) are widely found enriched in deep-sea sediment, yet the accumulation mechanisms remain debated. A lack of constraints on how early diagenesis overprints original seawater signals also limits the reliable application of REY proxies in the geological record. Here we present integrated geochemical analyses of sediments, porewater, and overlying seawater of two short sediment cores (24–36 cm) collected from the central Indian Ocean basins where REY-rich sediments developed. Despite generally oxic sedimentary conditions, early diagenetic alteration of porewater is characterized by elevated dissolved REY concentrations (18–103 nM) and pronounced middle REY enrichment, which is inferred to derive mainly from reductive or non-reductive dissolution of Fe-Mn (oxyhydr)oxides. Variations in porewater shale-normalized REY patterns reflect competitive partitioning of REY among various geochemical compositions in sediments, highlighting strong coupling between porewater and reactive sediment components. The high porewater REY concentrations may be attributed to relatively low phosphate contents in sediments, and to the stabilization of dissolved REY in colloidal phases, as indicated by the flat patterns when normalizing leachable REY fractions by porewater. Combining the data obtained in this study and previous studies, substantial REY enrichment in deep-sea sediments requires a combination of specific conditions, including limited carbonate dilution, oxic bottom water, low sedimentation rate, sufficient REY-bearing phases and moderate hydrothermal inputs. Overall, porewater acts as a dynamic reservoir and transfer medium during early diagenesis, facilitating REY redistribution and eventual fixation into REY-hosting minerals. These findings provide crucial insights into the mechanisms of REY enrichment in deep-sea sediments and demonstrate that porewater REY serve as sensitive recorders of early diagenetic processes, with important implications for interpreting REY signals preserved in sedimentary archives.</div></div>","PeriodicalId":327,"journal":{"name":"Geochimica et Cosmochimica Acta","volume":"425 ","pages":"Pages 251-265"},"PeriodicalIF":5.2,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147629818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}