Applied Geochemistry最新文献

{"title":"Biogenic sphalerite signatures and pH-dependent precipitation pathways","authors":"Chris Ingles ,&nbsp;John Mavrogenes ,&nbsp;Yue Wang ,&nbsp;Maria Cherdantseva ,&nbsp;David Saxey ,&nbsp;Denis Fougerouse","doi":"10.1016/j.apgeochem.2026.106677","DOIUrl":"10.1016/j.apgeochem.2026.106677","url":null,"abstract":"<div><div>Biogenic ore formation has long required clarification of depositional mechanisms and textural characteristics such as carbonate dissolution and ‘snow on the roof’. This research explored evidence for microbial sulfate reduction and biogenic mineralisation associated with sulfide ore deposits, using sphalerite from eight locations. Sulfur isotopic and microtextural analyses were conducted on sphalerites from Navan (Ireland), Wiesloch (Germany), Broken Hill supergene, Century and Cadjebut (Australia), Pomorzany (Poland), Balmat (USA) and Geco (Canada), using Sensitive High-Resolution Ion Microprobe, X-ray Fluorescence Microscopy, fluorination, cathodoluminescence, and atom probe tomography. Results correlated microbial sulfate reduction to stromatolitic zonation accompanied by strongly negative δ³⁴S (−10 to −40) and δ³³S (−5 to −20). Mississippi Valley-type sphalerites were classified as either MVTa (abiotic) or MVTb (biotic). The colloform banding suggest cyclic ore deposition, which led to the construction of pH dependent precipitation pathways that begin with acidic fluids and evolve into alkaline conditions with ongoing microbial activity. While sulfate reducing bacteria are the most likely organisms associated with sulfide mineralisation, syntrophic microbial communities are also suggested as avenues to process organic compounds such as hydrocarbons and aid sulfate reduction. The distinct isotopic signatures indicate that sphalerite from Navan, Wiesloch and the supergene Broken Hill ores formed from biogenic sulfate reduction. Rayleigh-type closed system isotopic fractionation was identified in abiotic sphalerite from Pomorzany and mass-independent fractionation (resemblant of pre-Great Oxidation Event conditions) in sphalerite from Geco.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106677"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chromium isotope fractionation in the redox-stratified Chesapeake Bay","authors":"Debbrota Mallick ,&nbsp;Xiangli Wang ,&nbsp;Marzia Miletto ,&nbsp;Jeffrey W. Krause ,&nbsp;Daniel C. Ohnemus ,&nbsp;Noah J. Planavsky ,&nbsp;George W. Luther ,&nbsp;Timothy W. Lyons ,&nbsp;Bradley M. Tebo","doi":"10.1016/j.apgeochem.2025.106671","DOIUrl":"10.1016/j.apgeochem.2025.106671","url":null,"abstract":"<div><div>The chromium (Cr) stable isotope compositions of sedimentary rocks have been used to track the evolution of oxygen levels in Earth's ocean-atmosphere system. However, the Cr isotope fractionation during transfer of dissolved Cr to sediments is still unclear. The Chesapeake Bay is a seasonally redox-stratified estuary (oxic surface water overlying euxinic, or sulfide-bearing, deep water) and thus provides a good opportunity to investigate Cr isotope fractionation in euxinic systems. Here we report total dissolved Cr concentrations and stable isotope compositions (δ⁵³Cr) of a water column in this estuary. As salinity increases from 7.51 in the oxic surface water to 19.22 in the euxinic deep water, total dissolved Cr concentration decreases from 1.21 nmol kg⁻¹ to 0.51 nmol kg⁻¹, while δ⁵³Cr decreases from 0.60 ‰ to −0.41 ‰. Explaining these data requires partial reduction of Cr(VI) to Cr(III) followed by incomplete scavenging of Cr(III) from solution, which leads to isotope fractionation during removal of Cr from seawater to anoxic sediments. An extensive compilation of redox-stratified systems suggests that Cr isotope fractionation during removal from anoxic water column is a common phenomenon. This has major implications for using the δ⁵³Cr of anoxic sediments to reconstruct paleo-seawater δ⁵³Cr values. Correcting for such fractionation will require better understanding of its governing factors, which would need more data for sediment trap, porewater, and redox-specific water column samples from anoxic settings.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106671"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Negligible isotope ratio variation assumption: Significant errors in mixing model but minimal impact on Rayleigh distillation model","authors":"Yuyang He","doi":"10.1016/j.apgeochem.2025.106668","DOIUrl":"10.1016/j.apgeochem.2025.106668","url":null,"abstract":"<div><div>Isotope geochemistry examines the geochemical properties of isotopes within the same element, which are influenced by subtle mass differences. A common assumption in traditional isotope theories is that variations in isotope ratio (<em>R</em>) are sufficiently small to be considered negligible, expressed as 1+<em>R</em>_X ≈ 1+<em>R</em>_Y, named Negligible Isotope Ratio Variation Assumption. Here, X and Y represent sample and standard in the <em>delta</em> notations, distinct endmembers in mixing models, or residual components at progressive stages in Rayleigh distillation models. While this assumption simplifies theoretical models, it may fail when dealing with isotopically enriched or depleted samples, such as synthetic tracers (e.g., ¹⁸O-enriched water), or extraterrestrial samples (e.g., hydrogens in solar wind). Moreover, in Rayleigh distillation processes, the <em>R</em> value of residual phases can theoretically approach infinity, significantly deviating from the initial <em>R</em>₀ value, rendering an important simplification in classical Rayleigh distillation model invalid. To quantify errors arising from this assumption, this study conducted rigorous mathematical analyses. The results demonstrate that the error in binary mixing models depends on the <em>R</em> value differences between endmembers, while Rayleigh distillation models exhibit a maximum error of ∼1‰ under isotope fractionation factors of 0.9 to 1.1, independent of isotope abundance. These findings highlight the robustness of certain approximations while emphasizing the need to consider model limitations in specific scenarios.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106668"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogical constraints on carbon deportment in phosphate ores: Implications for decarbonizing ore processing","authors":"Abdelaziz Zine ,&nbsp;Abdellatif Elghali ,&nbsp;Radouan El Bamiki ,&nbsp;Nouhaila Attalir ,&nbsp;Mustapha Mouflih ,&nbsp;Jérémie Aubineau ,&nbsp;Fleurice Parat ,&nbsp;Manuel Munoz ,&nbsp;Oussama Khadiri Yazami ,&nbsp;Jean-Louis Bodinier","doi":"10.1016/j.apgeochem.2025.106672","DOIUrl":"10.1016/j.apgeochem.2025.106672","url":null,"abstract":"<div><div>The release of CO₂ from carbon-bearing minerals during phosphate ore processing contributes to industrial emissions but remains poorly quantified. This study examines the Bouchane phosphate deposit, part of the Gantour Basin in Morocco, which consists of Upper Cretaceous–Paleogene sedimentary phosphates. The objective is to constrain the proportions and deportment of carbon within its mineral phases and assess their contribution to CO₂ release during beneficiation and acidulation. For this purpose, 20 representative samples from a stratigraphic section of the deposit were analyzed for petrographic composition, bulk mineralogy by X-ray diffraction, bulk geochemistry by inductively coupled plasma optical emission spectroscopy (ICP-OES), and total carbon by induction furnace, complemented by in-situ microanalyses using an electron probe micro-analyzer (EPMA) and quantitative automated mineralogy with a TESCAN Integrated Mineral Analyzer (TIMA). Moreover, the modal composition of the studied samples was determined using various approaches such as quantitative X-ray diffraction (QXRD), quantitative automated mineralogy (QAM), element-to-mineral conversion (EMC), and total inversion (TI). The studied samples were predominantly composed of phosphatic coated grains, peloids, coprolites, and skeletal particles. The chemistry of these sediments varied along the stratigraphic section, marked by a dominance of inorganic carbon compared to organic carbon, with a mean content of 11.38 ± 4.58 wt% and 0.68 ± 0.03 wt%, respectively. The developed calculated mineralogy techniques (EMC, TI) proved successful in accurate quantification of the modal composition of the phosphate sediments. Automated mineralogy by TIMA provided a quantification of the percentage of problematic locked carbonates within phosphatic grains, with values below 3 %. These grains were predicted to hold 11 % of the CO₂ in carbonate fluorapatite (CFA), and 0.3 % and 0.1 % in calcite and dolomite, respectively. The remaining carbonate phases are removed during washing and flotation. This study shows that adopting holistic approaches in phosphate mining is efficient for developing rapid, low-cost techniques for mineralogical characterization (EMC, TI) and indicates that phosphate rock processing results in limited in situ CO₂ release from carbonate minerals.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106672"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 salinity on nitrogen cycling and microbial community functional potential in groundwater of the Yellow river delta","authors":"Huan Wang ,&nbsp;Chuanshun Zhi ,&nbsp;Yufei Jiao ,&nbsp;Dan Xu ,&nbsp;Wenfeng Gao ,&nbsp;Yawei Kou ,&nbsp;Xiancang Wu ,&nbsp;Jing Bai ,&nbsp;Hui Mu ,&nbsp;Houliang Lu ,&nbsp;Xiaonong Hu","doi":"10.1016/j.apgeochem.2025.106669","DOIUrl":"10.1016/j.apgeochem.2025.106669","url":null,"abstract":"<div><div>Microorganisms in shallow groundwater of river deltas play a key role in nitrogen cycling, yet little is known about this process in high-salinity regions. This study examines how salinity affects nitrogen cycling and microbial function in the Yellow River Delta's high-salinity groundwater. Through combined hydrochemical, microbial, and genetic analyses, the study reveals that groundwater is high saline, mainly of the Na–Cl type, with ammonium as the dominant nitrogen form under reducing conditions. Microbial communities vary with salinity and redox conditions, and nitrogen cycling is mainly driven by DNRA and denitrification. Functional genes related to nitrogen metabolism strongly correlate with ammonium levels, emphasizing ammonium's regulatory role. Different hydrochemical factors shape nitrogen cycling at varying salinities: pH, I⁻, and Mg²⁺ at low salinity; K⁺ and sulfide at medium salinity; and TDS, Cl⁻, SO₄²⁻, and Na⁺ at high salinity. Overall, reductive pathways dominate, with denitrification (35.88 %) and DNRA (31.03 %) as the main processes. Under varying salinity conditions, nitrogen cycling pathways shift significantly: low-salinity favors nitrogen fixation, nitrification and DNRA, promoting both nitrogen input and loss; medium-salinity supports active nitrogen turnover through enhanced nitrification, denitrification, and ANRA; while high salinity leads to DNRA dominance, ammonium accumulation, and reduced nitrogen removal due to suppressed nitrification and denitrification. High-salinity selects for DNRA-performing, salt-tolerant microbes, enriching DNRA genes (<em>narGHI, nirBD</em>), while denitrification genes (<em>nosZ, nirK</em>) are more abundant at lower salinities.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106669"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resolving false positive Eu anomaly in seep carbonates with high Ba/Sm ratio using DGA resin separation","authors":"Xudong Wang ,&nbsp;Lanlan Zhang ,&nbsp;Tongtong Bai ,&nbsp;Jean-Alix Barrat ,&nbsp;Zhaoyang Wang ,&nbsp;Zice Jia ,&nbsp;Dong Feng","doi":"10.1016/j.apgeochem.2025.106670","DOIUrl":"10.1016/j.apgeochem.2025.106670","url":null,"abstract":"<div><div>The contents and distribution patterns of rare earth elements (REEs) are powerful tools for reconstructing fluid sources and redox conditions in marine sedimentary environments. However, their accurate determination in carbonate rocks is often complicated by low REE abundances and high barium (Ba) contents, which cause severe isobaric interference with europium (Eu) during conventional ICP-MS analysis due to the formation of BaO⁺ or BaOH⁺ polyatomic ions. In this study, we applied a validated DGA resin separation technique to analyze REEs from 30 Ba-rich authigenic carbonate samples from nine seep sites in the Gulf of Mexico. Before and after DGA separation, REE analyses were conducted on both bulk carbonate rock and carbonate fraction of carbonate rock (hereafter carbonate fraction). Ba contents ranged from 201 ppm to 91200 ppm in the bulk carbonate rock, and from 28 ppm to 1700 ppm in the carbonate fraction. Prior to separation, Eu/Eu∗ values ranged from 1.40 to 80.49 in bulk rock and from 1.44 to 17.65 in the carbonate fraction, with strong correlation to Ba/Sm ratios, indicating Ba-induced analytical artifacts. After DGA resin separation, Eu/Eu∗ values decreased to 1.10–1.16 in bulk rock and 1.11–1.22 in the carbonate fraction, confirming the elimination of false Eu anomaly. These results demonstrate that Ba-related interference can lead to substantial misinterpretation of REE data in Ba-rich samples. We advocate for routine chemical separation of REEs from matrix elements prior to ICP-MS analysis to ensure accurate paleoenvironmental reconstructions in seep and other Ba-enriched sedimentary settings.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106670"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance of oilfield brines and vertical connectivity of Middle to Upper Jurassic sequence in eastern Saudi Arabia","authors":"Peter Birkle ,&nbsp;Ahmed J. Zayer","doi":"10.1016/j.apgeochem.2025.106673","DOIUrl":"10.1016/j.apgeochem.2025.106673","url":null,"abstract":"<div><div>Knowledge of reservoir connectivity is crucial for optimizing oil recovery, accurately estimating reserves, planning well placement, and improving economics of an oil field. This study combines hydrochemical (major, minor, trace elements) and multi-isotopic techniques (δ²H, δ¹¹B, δ¹³C, ¹⁴C, δ¹⁸O_H2O, δ¹⁸O_SO4, δ³⁷Cl, δ⁸¹Br, δ³⁴S_SO4, ⁸⁷Sr/⁸⁶Sr) on oilfield brines to define reservoirs dynamics by tracing fluid provenance and migration. As case study, preserved bottom-hole water samples were recovered along a 1930’ vertical column of seven groundwater horizons from a Middle to Upper Jurassic carbonate-anhydrite sequence in an exploratory well in the eastern region of Saudi Arabia. Geochemical fluid homogeneities reveal hydraulic connectivity between the Lower Tithonian and Upper Kimmeridgian sequence, suggesting the presence of a single reservoir. Isotopic heterogeneities reveal sealing conditions between underlying Lower Kimmeridgian, Oxfordian (Hanifa), and Bathonian (Upper Dhruma) groundwater systems. Interlayered anhydrite strata resulted in possessing ambivalent hydrodynamic functionalities, either as conduits or seals. Studied formation waters are composed of Na–Cl to Na–Ca–Cl water type with a descending salinity from 210,500 mg/L (Tithonian) to 147,800 mg/L (Bathonian). Measured ¹⁴C concentrations from 2.01 pmC to 18.77 pmC point to recharge of the Jurassic sequence by infiltrating surface water during Late Pleistocene and Early Holocene, causing the mixing and partial replacement between 37 % and 55 % of fossil oilfield brine. A positive vertical trend of δ¹⁸O_SO4 - δ³⁴S_SO4 ratios, δ¹³C_PDB values between +8.4 ‰ and +16.2 ‰, and depleted δ¹¹B ratios reveal thermocatalytic sulfate reduction, methane production, and desorption of clay material, respectively, as major secondary water-rock interaction processes. As practical benefit, formation water analyses provide a low-cost and low-risk complementary tool to expensive and failure-prone production logging tools for evaluating reservoir conditions. The geochemical detection of hydraulic connectivity or compartmentalization between stratigraphic units represents a complimentary tool to trace the analogue migration of hydrocarbons within single or multiple pay zones.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106673"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"H–O–B–Li isotope systematics for assessing slab-derived fluids: Importance of postdehydration processes","authors":"Rofiqul Umam ,&nbsp;Ikuya Adachi ,&nbsp;Tsutomu Yamanaka","doi":"10.1016/j.apgeochem.2025.106667","DOIUrl":"10.1016/j.apgeochem.2025.106667","url":null,"abstract":"<div><div>In this study, the isotopic alteration of boron (B) and lithium (Li) in slab-derived fluids after they undergo dehydration processes is investigated using deep groundwater samples from the eastern Kii Peninsula of Japan. Isotopic and elemental analyses of hydrogen (H), oxygen (O), B, and Li reveal complex subsurface fluid mixing and geochemical interactions that exceed simple meteoric recharge. Three distinct groundwater groups were identified on the basis of δ²H–δ¹⁸O–Cl relationships: Group I has strong slab-derived water signatures, particularly along the Median Tectonic Line and near 34°50′N, with up to 60 % slab-derived contributions; Group II reflects mixing between meteoric water and ocean water; and Group III is predominantly meteoric. Spatial variations in δ¹¹B and δ⁷Li isotopes suggest that local geochemical processes such as clay adsorption, silicate weathering, and igneous rock contributions significantly alter the original slab-derived isotopic signals. Rayleigh-type fractionation models explain the increased isotopic values in some wells, whereas low δ¹¹B and δ⁷Li values elsewhere indicate localized sources. Notably, high Li values with low δ⁷Li values in the southwest indicate a Li supply from Miocene igneous intrusions beneath the Mesozoic accretionary complex. These findings highlight the need for an integrated multi-isotope approach to accurately trace fluid origins and reconstruct the geochemical pathways of slab-derived fluids in forearc groundwater systems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106667"},"PeriodicalIF":3.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrate aerosol and dust pollution evidence from a non-central-heating county in China","authors":"Mingya Wang ,&nbsp;Wenju Wang ,&nbsp;Mingshi Wang ,&nbsp;Xuechun Zhang ,&nbsp;Baoxian Jia","doi":"10.1016/j.apgeochem.2025.106675","DOIUrl":"10.1016/j.apgeochem.2025.106675","url":null,"abstract":"<div><div>As urbanization in China has shifted from major cities to surrounding counties, the study of PM_2.5 in these areas has gained significant attention. However, the pollution characteristics and sources of winter PM_2.5 in noncoal-heating counties in China remain unclear. In this study, PM_2.5 samples were collected from both urban and suburban functional areas in Xixian County, China. The mean PM_2.5 concentrations at the Xizhou Hotel (urban) and Primary School (suburban) sites were 81.4 ± 28.2 and 97.1 ± 35.7 μg/m³, respectively, with higher concentrations observed at the suburban site than at the mixed commercial and residential site. Two distinct haze types were identified: the first, dominated by Ca and Al, was primarily caused by windblown dust, including construction dust and soil dust from abandoned farmlands. The second, dominated by NO₃⁻, SO₄²⁻, and NH₄⁺, resulted from the secondary oxidation of primary gaseous precursors. Secondary pollutants (53.0 %) and vehicular traffic (24.9 %) were the major contributors. This study provides valuable data on the chemical characteristics and sources of winter haze in noncoal heating counties, providing a scientific basis for global PM_2.5 control strategies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106675"},"PeriodicalIF":3.4,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145904063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability of barite in thermochemical sulfate reduction: implications for primeval organic component preservation and metal sulfide mineralization","authors":"Yuan Wei ,&nbsp;Qian Wan ,&nbsp;Wenxuan Hu ,&nbsp;Xiaolin Wang","doi":"10.1016/j.apgeochem.2025.106666","DOIUrl":"10.1016/j.apgeochem.2025.106666","url":null,"abstract":"<div><div>Thermochemical sulfate reduction (TSR) is a common organic-inorganic interaction where sulfates react with hydrocarbons at elevated temperatures, producing reduced sulfur and oxidized carbon. The stability of barite in TSR is a critical scientific question because barite-hosted inclusions are reported to record primeval organic matters and barite can be involved in the formation of Sedimentary Exhalative and Mississippi-Valley type deposits. Here we performed systematic hydrothermal experiments and thermodynamic simulations to identify the key factors controlling TSR between barite and hydrocarbons. Results show that in anhydrous and neutral aqueous environments, barite and hydrocarbons can coexist stably at temperatures below 150 °C. Such condition is comparable with that reported for the formation of ∼3.5 Ga barite in Pilbara Craton, Western Australia, indicating that barite-hosted inclusions can record original information for Archean life evolution. At higher temperature and low pH conditions, barite can react with hydrocarbon to generate H₂S and CO₂. Fluid acidity (i.e., H⁺ concentration) and temperature are the most prominent factors controlling the involvement of barite in TSR. Therefore, consumption of preexisting H₂S (either TSR or other origin) by precipitation of metal sulfides (e.g., sphalerite and galena) can generate excess H⁺, which favors the involvement of barite in TSR. Obviously, barite can serve as a sulfur source for the formation of metal sulfide deposits. In conclusion, our findings offer new insights into researches of early Earth environments and the mineralization mechanisms of metal deposits.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"197 ","pages":"Article 106666"},"PeriodicalIF":3.4,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}