Applied Geochemistry最新文献

{"title":"Unraveling stress-mediated fluid-fault interactions in 2021–2022 seismic sequence: Insights from unsupervised machine learning and multiparametric hydrochemical anomalies in Xianshuihe fault zone","authors":"Yucong Yan ,&nbsp;Zheming Shi ,&nbsp;Xiaocheng Zhou ,&nbsp;Guangcai Wang ,&nbsp;Zuochen Zhang ,&nbsp;Yunfei Bai ,&nbsp;Zhaojun Zeng ,&nbsp;Bingyu Yao ,&nbsp;Yuwen Wang ,&nbsp;Miao He ,&nbsp;Jiao Tian ,&nbsp;Ruibin Li ,&nbsp;Han Yan","doi":"10.1016/j.apgeochem.2025.106635","DOIUrl":"10.1016/j.apgeochem.2025.106635","url":null,"abstract":"<div><div>Earthquake-related hydrochemical changes in thermal springs have been widely observed, yet the temporal dynamics and controlling mechanisms of pre- and post-seismic hydrochemical changes remains poorly constrained. By employing unsupervised machine learning (SOM-KM), this study investigates earthquake-induced changes of major elements, trace elements, and hydrogen-oxygen isotopes by high-frequency monitoring data in two thermal springs (XXX and LTG) along the Xianshuihe fault zone during the 2021–2022 Ms ≥ 6.0 earthquake sequence. The result shows that: the XXX spring (Moxi segment) exhibited consistent co-seismic dilution of major ions (Na⁺, K⁺, Cl⁻, HCO₃⁻) and trace elements, attributed to shallow fracture opening under low normal stress (200–400 MPa), thereby facilitating meteoric water recharge (81–89 % mixing ratio). Conversely, the LTG spring (Kangding segment) showed enrichment of deep-sourced constituents of pre-seismic major elements (Na⁺, K⁺, Cl⁻, HCO₃⁻) surges during the 2021 Luxian <em>M</em>s6.0 earthquake, and post-seismic trace element fluctuation in 2022 Ms ≥ 6.0 earthquake sequence, driven by high stress (400–600 MPa) enhancing deep fracture dilation, fluid ascent, and water-rock interaction (obvious δ¹⁸O drift). Cross-analysis of hydrogeochemical signatures with geological and geophysical evidence demonstrates that earthquake-induced hyrochemical anomalies are governed by (1) regional tectonics stress; (2) fault-segment heterogeneity; (3) fluid pathway reorganization and water-rock interaction dynamics. This work advances the understanding of fault-zone fluid response mechanisms to seismicity and offers novel insights into crustal fluid-tectonic interactions during earthquake cycles.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106635"},"PeriodicalIF":3.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570969","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 gradient on sediment microbial communities and the functions of carbon, nitrogen, and sulfur cycling in coastal zone","authors":"Dahai Wang ,&nbsp;Chuanshun Zhi ,&nbsp;Xiaonong Hu ,&nbsp;Zhen Wu ,&nbsp;Wei Song ,&nbsp;Jian Wang ,&nbsp;Xianrui Huang ,&nbsp;Fan Yang ,&nbsp;Yufei Jiao ,&nbsp;Yuxi Li","doi":"10.1016/j.apgeochem.2025.106609","DOIUrl":"10.1016/j.apgeochem.2025.106609","url":null,"abstract":"<div><div>Coastal sediments, located at the terrestrial–marine interfaces and subject to strong salinity gradients, harbor distinct microbial communities that play indispensable roles in sustaining carbon, nitrogen, and sulfur cycling, yet the responses to salinization remain insufficiently understood. This study aims to characterize microbial community structures within coastal sediments by employing high-throughput sequencing of the 16S rRNA gene. Furthermore, we utilized the FAPROTAX and PICRUSt2 prediction tools to elucidate microbial functions and biogeochemical cycling processes in these sediment ecosystems. The results revealed that increasing salinity significantly increased microbial α-diversity and promoted the expansion of salt-tolerant microbial populations. The salinity-driven increase in microbial network complexity was accompanied by more pronounced competitive interactions. Salinity variations also significantly altered the microbial functions associated with carbon, nitrogen, and sulfur cycling in the sediments. In low-salinity environments, the ability to decompose complex carbon sources was higher, while in high-salinity environments, microbial communities relied more on chitin degradation, starch degradation, and reductive acetogenesis to cope with the high-salinity, low-oxygen conditions. In the nitrogen cycle, mild salinization promoted denitrification, but in the later stages of salinization, high salinity suppressed denitrification, while nitrogen fixation was enhanced in high-salinity environments. The sulfur cycle, both sulfur oxidation and reduction processes were active in medium-salinity sediments, whereas sulfur oxidation was more pronounced and sulfur reduction was diminished in high-salinity sediments, particularly sulfide oxidation and thiosulfate oxidation were enhanced, while dissimilatory sulfate reduction was weakened. This study reveals the effects of salinity gradients on sediment microbial communities and their functions, providing theoretical support for future ecological restoration and environmental management.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106609"},"PeriodicalIF":3.4,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555195","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":"Strontium isotopes and Rb/Sr tracers in surface soils for locating subsurface lithium pegmatites","authors":"Grace A. Hall ,&nbsp;Gordon D.Z. Williams ,&nbsp;Mona-Liza C. Sirbescu ,&nbsp;P. Louis Lu ,&nbsp;Gary S. Dwyer ,&nbsp;Daniel D. Richter ,&nbsp;Avner Vengosh","doi":"10.1016/j.apgeochem.2025.106631","DOIUrl":"10.1016/j.apgeochem.2025.106631","url":null,"abstract":"<div><div>Lithium-cesium-tantalum (LCT) pegmatites are a major source of global Li production. They typically occur as dike swarms intruded into metamorphic country rocks. The subsurface locations of these dikes can be difficult to identify from the surface. One common approach is to investigate geochemical anomalies in overlying soils and use these as indicators for the occurrence of subsurface pegmatite dikes. However, even with these methods, economically valuable pegmatites can be difficult to identify, and additional techniques can be beneficial for optimizing geological exploration. Here we present a new methodology for detecting subsurface pegmatites through the analysis of Rb/Sr and strontium isotope (⁸⁷Sr/⁸⁶Sr) variations in relatively shallow soils overlying LCT pegmatites. During their formation, pegmatites become enriched in Rb and depleted in Sr, resulting in distinctly high Rb/Sr ratios (typically ≫10), and with time, the decay of ⁸⁷Rb leads to high ⁸⁷Sr/⁸⁶Sr ratios (typically ≫1.0) far exceeding those of common regional host rocks (typically with Rb/Sr &lt; 10 and ⁸⁷Sr/⁸⁶Sr &lt; ∼0.75). Since soils primarily inherit the ⁸⁷Sr/⁸⁶Sr values of their underlying parent rocks, we propose using these distinctive geochemical fingerprints in site-specific soil geochemical surveys to detect subsurface LCT pegmatites. We demonstrate the potential and utility of this methodology using surface soils around and overlying buried LCT pegmatites in the Late Paleozoic Tin Spodumene Belt in North Carolina and the Proterozoic Animikie Red Ace in Wisconsin, USA. Soils directly overlying the LCT pegmatites inherit distinctly elevated Rb/Sr (∼10–120) and ⁸⁷Sr/⁸⁶Sr (∼1.0–6.8) ratios compared to background soils away from the buried LCT pegmatites (⁸⁷Sr/⁸⁶Sr ∼0.74–0.77, Rb/Sr ∼0.76–3.9), which can be used to identify and reconstruct the location of subsurface LCT pegmatite dikes. The common and uniquely elevated Rb/Sr and ⁸⁷Sr/⁸⁶Sr signatures of global pegmatites suggest that this method can be widely and globally applied to soils derived from LCT pegmatites.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106631"},"PeriodicalIF":3.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577392","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":"Contrasting cadmium isotope compositions in sediments from the eastern and western new Britain Trench: Implications for source tracing and marine geochemical cycling","authors":"Qiang Dong ,&nbsp;Cailing Xiao ,&nbsp;Yong Liang ,&nbsp;Jingqian Xie ,&nbsp;Min Luo ,&nbsp;Yanwei Liu ,&nbsp;Yingying Guo ,&nbsp;Yingming Li ,&nbsp;Yongguang Yin ,&nbsp;Yong Cai ,&nbsp;Guibin Jiang","doi":"10.1016/j.apgeochem.2025.106632","DOIUrl":"10.1016/j.apgeochem.2025.106632","url":null,"abstract":"<div><div>Trench sediments are recognized as a major sink in the marine cadmium (Cd) budget, however, the sources and biogeochemical cycling of Cd in hadal environments remain poorly constrained. This study investigated Cd concentrations and isotope compositions (δ^114/110Cd) in surface sediments (1553–8931 m water depth) from the western and eastern New Britain Trench. Cd concentrations ranged from 105 to 245 μg kg⁻¹, with δ^114/110Cd from −0.26 ‰ to −1.34 ‰, significantly lighter than deep seawater. Isotope tracing reveals that detrital Cd (in the crystalline mineral matrix) accounts for 34–84 % in the western and 64–87 % in the eastern transect. The δ^114/110Cd_non-detrital in shallow sediments differed markedly between western (−0.39 ‰) and eastern (−2.18 ‰) trenches, suggesting distinct sources. Terrigenous inputs, relatively enriched heavy Cd isotopes, dominate in the west, while biogenic particles sinking are likely dominant source in the east. Sedimentary δ^114/110Cd increased in the eastern transect with depth due to stepwise scavenging of light isotopes, whereas in the western transect it first decreased and then increased, reflecting variations in sediment components and redox conditions. These findings underscore the combined effects of source heterogeneity and depositional processes on Cd isotopes composition in trench sediments, offering new insights into deep-ocean metal cycling.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106632"},"PeriodicalIF":3.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577442","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":"Qualitative impact of hypersaline wetland on adjacent aquifers: Hydrochemical and isotopic perspectives","authors":"Marzieh Kabe,&nbsp;Mohsen Rezaei","doi":"10.1016/j.apgeochem.2025.106628","DOIUrl":"10.1016/j.apgeochem.2025.106628","url":null,"abstract":"<div><div>Disruption of the natural interaction between groundwater and the Tashk-Bakhtegan Wetland (TBW) has disturbed the dynamic balance of groundwater-surface water systems, increasing the salinity of adjacent groundwater resources. This study investigates the mechanisms of water flow interactions between the TBW in southern Iran and its surrounding aquifers. To investigate the hydrogeochemical processes and salinity mechanisms influencing groundwater near the TBW, 47 water samples were collected from deep and semi-deep wells and the wetland. In situ parameters, including electrical conductivity, temperature and pH, major constituents, and stable isotopes (δ¹⁸O and δ²H) were analyzed in these samples. The spatial distribution of electrical conductivity indicates increasing salinity near the hypersaline wetland. Within a short distance within the aquifers, the water type shifts from Ca–Mg–HCO₃ in recharge boundaries to the domnant water types of Na–Cl. The results indicate that groundwater salinization is driven primarily by reverse ion exchange, mixing with brine, and geological interactions. Hydrogeochemical facies evolution (HFE) models and SO₄/Cl ratios confirm saltwater intrusion into freshwater aquifers. Heavier δ¹⁸O and δ²H ratios in surface water ratios collected from the TBW suggest mixing processes between hypersaline wetland water and meteoric freshwater. The present study may serve as a warning about the vulnerability of adjacent aquifers to salinity intrusion and emphasize the need for sustainable water resource management in the region.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106628"},"PeriodicalIF":3.4,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518710","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":"Biased selection and incomplete characterization of feedstock materials in enhanced rock weathering experiments","authors":"Benjamin Möller ,&nbsp;Xavier Dupla","doi":"10.1016/j.apgeochem.2025.106630","DOIUrl":"10.1016/j.apgeochem.2025.106630","url":null,"abstract":"<div><div>Terrestrial Enhanced Rock Weathering (ERW) – the application of crushed rocks to soils to accelerate CO₂ removal – has emerged as a promising climate mitigation strategy to complement emission reduction efforts. One of the key factors controlling the efficacy of ERW is the composition of the utilized rock powder, ultimately constraining the achievable CO₂ removal potential and rate in a given environment. In this article, we highlight that experimental research on ERW is dominated by a narrow range of commercially available rock powders, arguably often selected more for convenience than for relevance. These materials are often poorly characterized, neglecting core methods and principles of petrography. In combination, these shortcomings are detrimental to our understanding of ERW's potential and our ability to guide its successful implementation. We call for a systematic and detailed evaluation of all potential feedstocks, going beyond readily available products. In doing so, we hope to better constrain experimental results and inform on ERW's overall CO₂ removal capacity.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106630"},"PeriodicalIF":3.4,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518711","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":"Reconstructing coalbed methane accumulation history in the Qinshui Basin using noble gas isotopes","authors":"Zhelin Zhang ,&nbsp;Biying Chen ,&nbsp;Yi Liu ,&nbsp;Zhanjie Xu ,&nbsp;Finlay M. Stuart ,&nbsp;Sheng Xu","doi":"10.1016/j.apgeochem.2025.106629","DOIUrl":"10.1016/j.apgeochem.2025.106629","url":null,"abstract":"<div><div>Coalbed methane (CBM) is an unconventional natural gas resource that supports low-carbon energy demand and mitigates greenhouse gas emissions during coal mining. It is a key natural gas resource in China. Understanding how CBM is produced and accumulates is critical for exploration. Qinshui Basin is the largest and most productive CBM basin in China. This study uses the light noble gas compositions (He, Ne and Ar) of CBM from five blocks in the Qinshui Basin to provide a comprehensive view of gas accumulation history. The noble gases are derived from air and deep crustal sources. Gases from these sources were mixed in formation water prior to methane extraction. Subsequent degassing followed open-system Rayleigh fractionation, enabling the crustal ⁴He and ⁴⁰Ar accumulation ages and the gas-water interaction volume to be determined, as well as the proportion of desorbed methane released during production. The coal seams have incorporated the flux of ⁴He and ⁴⁰Ar from the deep crust. Despite this, the crustal ⁴He and ⁴⁰Ar accumulation ages are considerably younger than the Permo-Carboniferous coal deposition age, revealing widespread gas loss. Adsorbed methane was released during gas extraction. The proportion of desorbed methane in the produced gas shows a strong relationship with crustal ⁴⁰Ar accumulation ages, indicating that the noble gases serve as a proxy for the preservation of adsorbed methane. The interacted gas/water ratios derived from air-sourced noble gases reflect the extent of gas extraction. Low extraction efficiency is indicated by low gas/water ratios, high dilution ratios and low gas production rates, while prolonged high extraction rates lead to a decline in the dilution ratio. These findings demonstrate the value of measuring trace noble gases for understanding gas accumulation and guiding CBM production strategies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106629"},"PeriodicalIF":3.4,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518740","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":"Estimation of flow dynamics of saline groundwater in a coastal geothermal region based on B–Li–Cl classification and geochemical measurements","authors":"Tsuyoshi Shintani ,&nbsp;Keiichi Tomita ,&nbsp;Noritoshi Morikawa","doi":"10.1016/j.apgeochem.2025.106625","DOIUrl":"10.1016/j.apgeochem.2025.106625","url":null,"abstract":"<div><div>Coastal geothermal saline groundwater (SGW) in Quaternary volcanic regions represents an important geothermal resource, but its complex chemical compositions often obscure its origin and dynamics. This study aims to elucidate the SGW dynamics in the coastal plain of Hakodate, Hokkaido, in Japan using the B–Li–Cl to delineate water-rock interactions and diagenesis, and to classify SGW type. Major dissolved components and stable isotopes (δ²H, δ¹⁸O) are susceptible to freshwater dilution, limiting their diagnostic utility. The B–Li–Cl composition allowed for the classification of SGW into three types (Type 1, 2, and 3). Types 1 and 2 were influenced by direct seawater contributions and other origins such as diagenesis and volcanic gas, respectively. Type 3, with higher B (Boron) and Li (Lithium) concentrations than the other SGW, is distributed in the geothermal region, and reflects seawater modified by interaction with rocks at 175 ± 25 °C. Integration of chemical equilibrium modeling and geothermometer supports this geochemical evolution of the SGWs. Additionally, hydrogeological analyses have estimated that the flow dynamics of Type 3 waters are recharged through fractures near offshore submarine volcanic vents that migrate to deeper subsurface regions. These findings offer new insights into coastal hydrothermal systems in the study area. The Li and B concentrations serve as effective tracers for elucidating the origin of SGW in coastal geothermal regions, and their application is expected to lead to a more comprehensive understanding of SGW flow dynamics.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106625"},"PeriodicalIF":3.4,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577443","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":"Molybdenum and Antimony immobilization by iron oxalate salt in contaminated soils","authors":"Amandine Dumas ,&nbsp;Laurent De Windt ,&nbsp;Ivan Serclerat ,&nbsp;David S. Kosson ,&nbsp;Bruno Huet ,&nbsp;Florence Sanchez ,&nbsp;Nouffou Tapsoba","doi":"10.1016/j.apgeochem.2025.106626","DOIUrl":"10.1016/j.apgeochem.2025.106626","url":null,"abstract":"<div><div>This study introduces iron oxalate dihydrate (FeOx) as an innovative and highly effective treatment for the chemical stabilization of trace levels of Mo and Sb in soils. The effectiveness of the FeOx treatment was evaluated for a Mo-contaminated limestone tunnel sludge (LTS) and Mo/Sb-contaminated industrial wasteland soil (IWS) with organic matter. FeOx reactivity and oxyanion retention were investigated using TGA, XRD, optical microscopy and standardized US/EU leaching tests. Mineralogical changes and the pH-dependence on Mo sorption were further analyzed by geochemical modeling. Under near-neutral pH and oxidizing conditions, FeOx dissociates, releasing Fe²⁺ and C₂O₄²⁻ ions. The Fe²⁺ is subsequently oxidized to Fe³⁺, forming poorly crystallized hydrous ferric oxides (HFOs) that are uniformly distributed. This process induces acidification, partially dissolving calcite and releasing Ca²⁺, which reacts with C₂O₄²⁻ to form calcium oxalate monohydrate (whewellite). Mo and Sb immobilization occurs through sorption onto HFOs, achieving effective retention at ≥1 wt% FeOx for LTS and ≥5 wt% for IWS, meeting European inert waste standards. The fast transformation of FeOx into HFOs and whewellite enables Mo and Sb retention within 6 h. Overall, leaching decreased by 67 % for Mo in LTS with 2 wt% FeOx, and by 88 % for Sb and 90 % for Mo in IWS with 6 wt% FeOx. Retention stability was observed at pH ≤ 8, with no significant competition with sulfate or acetate ions. These results highlight FeOx as a promising solution for industrial applications requiring rapid chemical stabilization of contaminants. However, further research is needed to assess long-term stability under variable redox conditions.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106626"},"PeriodicalIF":3.4,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577444","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":"Hydrothermal experiments at in-situ conditions to identify Li release reactions by water-mineral interactions in deep sedimentary basins of the North German Basin and Upper Rhine Graben","authors":"Kevin Schmidt ,&nbsp;Martin Oeser ,&nbsp;André Stechern ,&nbsp;Christian Ostertag-Henning","doi":"10.1016/j.apgeochem.2025.106622","DOIUrl":"10.1016/j.apgeochem.2025.106622","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Lithium (Li) production from brines circulating in deep sedimentary basins as a byproduct of deep geothermal energy use could contribute to cover a significant proportion of the increasing global Li demand. Additionally, co-produced formation waters from the oil and gas industry represent another potential source of Li that could be utilized in a similar manner. Feasibility assessments for these operations require estimates for a possible Li replenishment by the recirculation of the Li-depleted brine after aboveground Li extraction. Currently, information about Li contents in reservoir rocks, the main Li carrier mineral phases of the respective reservoirs and possible Li release reactions are scarce.&lt;/div&gt;&lt;div&gt;In this study, drill core material from two geothermal wells, Groβ Buchholz Gt1 (Triassic Bunter sandstone) in the North German Basin (NGB) and Soultz-sous-Forêts EPS1 (granitic basement) in the Upper Rhine Graben (URG), as well as from the gas well Unterlüß T1 (Triassic Bunter sandstone) in the NGB, were investigated for both Li contents and Li release behavior. The bulk rock Li concentrations of the sample collection vary slightly in the range of 47–79 ppm. The main Li-bearing minerals were identified to be (i) chlorite (575 ppm) and illite (68 ppm) for Bunter sandstone samples and (ii) biotite for the Soultz sous forêts granite with maximum concentrations of up to 597 ppm. By grain-size fraction analysis phyllosilicates in the clay fraction were confirmed to exhibit the highest Li concentrations for the sandstones. To explore the Li release behavior, hydrothermal experiments were conducted at conditions of low enthalpy geothermal reservoirs (100–160 °C, 370 bar) for 14–60 days. The above described core samples were investigated by using ground rock powder and for one example the clay fraction. These solids were mixed with either bi-dist. H&lt;sub&gt;2&lt;/sub&gt;O or synthetic brine in Au capsules or in flexible Au–Ti reaction cells and installed in high pressure reactors. Results of the experiments show that a nearly constant Li concentration was attained after 6–12 days in all experiments with the bi-dist. H&lt;sub&gt;2&lt;/sub&gt;O. In these experiments, a total of 0.2–0.7 % of the Li contained in the granitic sample and 0.9–3.2 % of the Li contained in the Bunter sandstone samples were leached into the solution. It was found that different reaction mechanisms involving silicate minerals, as well as halogenide and carbonate minerals, contribute to the Li release. The experiment conducted with a clay fraction consisting mainly of illite and chlorite showed an enhanced leach of 6.9 % Li, indicating that Li is preferentially released by illite and chlorite in all experiments. Variations in temperature point only to a minor influence on the amount of Li released in the experiments. Experiments conducted with a synthetic brine instead of bi-dist. H&lt;sub&gt;2&lt;/sub&gt;O stimulated the release of Li by a factor of up to 2 for the Bunter sandstone samples and by a","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106622"},"PeriodicalIF":3.4,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577393","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}