Applied Geochemistry最新文献

{"title":"New perspectives on water chemistry classification of travertine/tufa","authors":"Qunwei Dai ,&nbsp;Ting Zhang ,&nbsp;Dejun An ,&nbsp;Jingwen He ,&nbsp;Jie Cui ,&nbsp;Qiongfang Li ,&nbsp;Ronglin Xu ,&nbsp;Faqin Dong ,&nbsp;Zheng Dang ,&nbsp;Qianxi Song","doi":"10.1016/j.apgeochem.2025.106386","DOIUrl":"10.1016/j.apgeochem.2025.106386","url":null,"abstract":"<div><div>If travertine/tufa is a solidified carrier of information records, karst water is the most important transport carrier of such information. In this study, we investigate the water chemistry of partial travertine/tufa around the world. Based on the better linear relationship between Ca²⁺ and HCO₃⁻, the classification view of Ca²⁺-biased and HCO₃⁻-biased types is proposed. Ca²⁺-biased is defined as a high Ca²⁺ concentration compared to the theoretical value of the chemical formula for Ca(HCO₃)₂, while HCO₃⁻-biased is defined as a high HCO₃⁻ concentration compared to the theoretical value of the chemical formula for Ca(HCO₃)₂. By comparing the concentrations of Ca²⁺ and HCO₃⁻ in hot and cold spring travertine/tufa around the world, the relationship between Ca²⁺-biased and HCO₃⁻-biased type is described, providing reference for the classification research of travertine/tufa.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106386"},"PeriodicalIF":3.1,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799875","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":"Combining sequential Gaussian co-simulation and Monte Carlo dropout-based deep learning models for geochemical anomaly detection and uncertainty assessment","authors":"Dazheng Huang ,&nbsp;Renguang Zuo ,&nbsp;Jian Wang ,&nbsp;Raimon Tolosana-Delgado","doi":"10.1016/j.apgeochem.2025.106385","DOIUrl":"10.1016/j.apgeochem.2025.106385","url":null,"abstract":"<div><div>Geochemical anomaly detection is crucial for guiding mineral exploration toward prospective mineral deposits. However, this task is inherently challenging due to uncertainties arising from sparse sampling, spatial variability of geochemical patterns, model limitations. To evaluate the uncertainties associated with spatial variability and model limitations, this study proposes an innovative approach that combines sequential Gaussian co-simulation (SGCS) with Monte Carlo (MC) Dropout-based Convolutional Neural Networks (CNNs) for geochemical anomaly detection and uncertainty quantification. The SGCS method generates multiple realizations of geochemical data, facilitating the quantification of uncertainty in geochemical patterns by considering potential distributions at unsampled locations. These realizations are utilized to augment the training dataset for CNNs, thereby enhancing the model's robustness in anomaly detection. The MC Dropout technique is integrated into the CNN model to evaluate prediction uncertainties, providing critical insights for decision-making under uncertainty. The proposed methodology was applied to the northwestern part of Sichuan Province, China, a region known for gold mineralization. Results indicate that all known gold deposits fall within areas where the anomaly probability exceeds 0.843. By integrating predicted probabilities with associated uncertainties, the spatial distribution of a confidence index is derived, offering a structured guide for subsequent exploration. This integrated framework enhances anomaly detection accuracy and provides robust uncertainty estimates, ultimately enabling more efficient and informed exploration strategies in high-uncertainty environments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106385"},"PeriodicalIF":3.1,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799874","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 effects of ecological restoration and sewage input on the carbonate system variability in an urban river on the Loess Plateau","authors":"Jiajia Dang ,&nbsp;Hong Yang ,&nbsp;Yunxiao Li ,&nbsp;Yunxiu Ma ,&nbsp;Xiao Wang ,&nbsp;Xiao Huang ,&nbsp;Fenwu Liu","doi":"10.1016/j.apgeochem.2025.106382","DOIUrl":"10.1016/j.apgeochem.2025.106382","url":null,"abstract":"<div><div>Intensive human disturbances have led to complex internal variations in the riverine CO₂ system, especially in the urbanized rivers in semi-arid areas. This study examines the factors controlling carbonate system in a river draining an urban ecological restoration area on the Loess Plateau, North China, where riverine dissolved inorganic carbon (DIC) and CO₂ partial pressure (<em>p</em>CO₂) exhibited pronounced variations influenced by land use changes. The most notable changes included a decrease in DIC (24.0 mg L⁻¹) and <em>p</em>CO₂ (280 μatm) in the urban restored area with damming, driven by strong aquatic photosynthesis, and a sharp increase in DIC (55.7 mg L⁻¹) and <em>p</em>CO₂ (6,222 μatm) in the urban downstream, attributed to sewage input. In contrast, in the upstream of the urban restored area, DIC (33.8 mg L⁻¹) and <em>p</em>CO₂ (723 μatm) were mainly controlled by carbonate weathering. Overall, this river acted as a strong atmospheric CO₂ source, with an average CO₂ emission of 450.1 mmol m⁻² d⁻¹, slightly higher than the global riverine average (359.4 mmol m⁻² d⁻¹), and exhibited pronounced spatial variability. A CO₂ sink (−11.2 mmol m⁻² d⁻¹) developed in the urban restoration area, whereas sewage input at urban downstream transformed the river into a strong CO₂ source (1,668.5 mmol m⁻² d⁻¹), highlighting the impact of anthropogenic perturbations on riverine CO₂ source - sink dynamics. Therefore, enhancing urban ecological restoration while effectively reducing CO₂ emission from sewage is crucial for achieving CO₂ neutrality in urban rivers, particularly in arid and semi-arid climates.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106382"},"PeriodicalIF":3.1,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785944","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":"Dissolution behavior of mechanical synthetic carbonate mixtures from the system ZnCO3–PbCO3–H2O in aqueous solution at 25 °C","authors":"Zongqiang Zhu ,&nbsp;Chengyou Ma ,&nbsp;Xiaoling Yu ,&nbsp;Xinghang Liu ,&nbsp;Peijie Nong ,&nbsp;Fei Luo ,&nbsp;Xiaoke Nong ,&nbsp;Lihao Zhang ,&nbsp;Shen Tang ,&nbsp;Zhiqiang Kang ,&nbsp;Yinian Zhu","doi":"10.1016/j.apgeochem.2025.106383","DOIUrl":"10.1016/j.apgeochem.2025.106383","url":null,"abstract":"<div><div>Understanding the ZnCO₃–PbCO₃–H₂O system is still a challenge for the thermodynamical modelling due to the different crystal structures of the two endmembers, rhombohedral smithsonite and orthorhombic cerussite. In the present work, a range of Pb-bearing smithsonite, Zn-bearing cerussite and their mixture having the bulk constituent Pb/(Zn + Pb) mole ratio (X_Pb) of 0.000–1.000 had been prepared and dissolved in water at 25 °C for 330 days. For dissolution in initially N₂-degassed water (NW) and CO₂-saturated water (CW), the average log IAPs (ion activity products) at the final stable state (≈log <em>K</em>_sp, solubility product constants) were computed to be −10.71 ± 0.07 ∼ −10.56 ± 0.06 and −10.88 ± 0.23 ∼ −10.89 ± 0.21 for smithsonite, −13.26 ± 0.04 ∼ −13.23 ± 0.08 and −12.72 ± 0.06 ∼ −12.69 ± 0.03 for cerussite, respectively. The incorporation of Pb into smithsonite would slightly increase the log IAPs for the Pb-smithsonite, while very small amount of the Zn incorporation into cerussite would significantly decrease the log IAPs for the Zn-cerussite. The Guggenheim parameters for the smithsonite (<em>R</em> <span><math><mrow><mover><mn>3</mn><mo>‾</mo></mover></mrow></math></span> <em>c</em>) – cerussite (<em>Pmcn</em>) solid solutions were estimated to be <em>a</em>₀ = 2.79 for the smithsonite-side and <em>a</em>₀ = 2.20 for the cerussite-side from the largest X_Pb in the Pb-smithsonite of 0.094 and the smallest X_Pb in the Zn-cerussite of 0.751. In the Lippmann diagrams for the smithsonite–cerussite–H₂O system, the (Zn_1-xPb_x)CO₃ solids dissolved incongruently, and the aqueous compositions evolved with time upward to the quasi-equilibrium curves for the Pb-smithsonite having a smaller X_Pb, and then along them from right to left, attained and intersected the <em>solutus</em> curve and the saturation curve for pure smithsonite, and finally moved upward to the saturation curve for cerussite. The Pb-poorer water solutions were finally at equilibrium with both the Zn-richer Pb-smithsonite and the Pb-richer Zn-cerussite. The result can offer a deep understanding of the geochemical and environmental behaviors of lead and zinc.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106383"},"PeriodicalIF":3.1,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768593","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":"Groundwater of the Eastern Egyptian Desert: age and salinity patterns","authors":"Manal Wannous ,&nbsp;Christian Siebert","doi":"10.1016/j.apgeochem.2025.106367","DOIUrl":"10.1016/j.apgeochem.2025.106367","url":null,"abstract":"<div><div>The increasing development of groundwater dependent irrigation projects and desalination activities along the Red Sea coast raises questions about its recharge mechanisms and the geochemical processes driving salinity variations. To address these questions, several wells and springs, along the Red Sea Hills have been sampled and analysed for radiocarbon, tritium, δ¹³C, δ¹⁸O, δ²H and their chemistry. For the same period between 2019-2021, rain and floodwater samples have been collected from sporadic rain events in the region. The sampling locations are geographically clustered and classified into six distinct groundwater types based on geochemical composition and isotopic signatures. The distinguished types exhibits a diverse range of geochemical and isotopic characteristics, reflecting variable flow paths, recharge periods, and lithological interactions. Freshwater springs in Wadi Araba are characterized by minimal salinization and light stable isotopes, suggesting Pleistocene recharge. These springs, emerge from fractures and are influenced by the weathering of Na-bearing minerals in the underlying Nubian Sandstone. In contrast, groundwater from the coastal plain shows significant contributions from seawater evaporation brines, with isotopic signatures following an evaporation trend. These waters vary widely in age, from recent to Pleistocene, indicating similar lithological interactions despite differing flow paths. Another group of groundwater is influenced primarily by the weathering of halite, gypsum, and dolostone, showing no significant brine contribution. Highly saline groundwater are rare and stands out with extreme brine contributions likely sourced from deep crustal formations. Groundwater with elevated Na/Cl ratios, found in regions of Wadi Araba and the Red Sea Hills, reflects the weathering of Na-bearing minerals such as feldspars in magmatic rocks or clastic sandstones. These waters contrast sharply with those influenced by seawater or evaporation brines, highlighting the complex interplay of lithology, recharge processes, and tectonic activity in shaping the region’s groundwater systems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106367"},"PeriodicalIF":3.1,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Evaluating the applicability of the VERHIB model to a 2600-year peat sequence from Central Germany","authors":"Carrie L. Thomas ,&nbsp;Boris Jansen ,&nbsp;E. Emiel van Loon ,&nbsp;Guido L.B. Wiesenberg","doi":"10.1016/j.apgeochem.2025.106338","DOIUrl":"10.1016/j.apgeochem.2025.106338","url":null,"abstract":"<div><div>Plant-derived biomarkers have been used extensively for source identification of organic matter in soil, peat, and sediments. These are chemical components, primarily of leaf waxes, that are naturally more resistant to degradation than most organic molecules and can be preserved in depositional archives for hundreds to thousands of years. However, using biomarkers for vegetation reconstruction can be complicated because individual compounds or compound classes do not necessarily indicate specific plant sources. The composition across multiple compounds must be holistically evaluated to develop accurate reconstructions. The VERHIB model was developed to enable a range of <em>n</em>-alkane and <em>n</em>-alkanol data to be evaluated simultaneously and estimate past vegetation development using the biomarker signature of leaves and roots from present-day specimens of the plant species of interest compared to the preserved, mixed signature of a soil or peat core. In this study, we have applied the VERHIB model to data gathered from the Beerberg peatland in Central Germany. A previous study characterized plant macrofossils, pollen, <em>n</em>-alkane, <em>n</em>-alkanol, and <em>n</em>-fatty acid composition in the Beerberg peat. We have collected modern plant samples from the peatland and measured their biomarker composition to use as input for the model. Despite many overlapping biomarker signatures across plant species and parts, our results show that the model could recreate a reasonable vegetation development pattern for most of the peat core if <em>n</em>-fatty acid data were included alongside <em>n</em>-alkane data. The model had difficulty recreating the transition from poor fen vegetation to <em>Sphagnum</em> bog, which was evident in the plant macrofossil records, so further calibration is needed. This was the first attempt at considering <em>n</em>-fatty acid data in a reconstruction using the VERHIB model; previous reconstructions only included <em>n</em>-alkanes or a combination of <em>n</em>-alkanes and <em>n</em>-alkanols. Our study shows that <em>n</em>-fatty acids are a valuable compound class to add to the VERHIB model and provides recommendations for future development.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106338"},"PeriodicalIF":3.1,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143740074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Mineralogical and geochemical characterization of mine tailings in the King river delta, Western Tasmania: Implications for long-term stability of trace elements","authors":"Sibele C. Nascimento ,&nbsp;David R. Cooke ,&nbsp;Matthew J. Cracknell ,&nbsp;Clare B. Miller ,&nbsp;Anita Parbhakar-Fox","doi":"10.1016/j.apgeochem.2025.106366","DOIUrl":"10.1016/j.apgeochem.2025.106366","url":null,"abstract":"<div><div>Nearly a century of mining activities at the Mount Lyell Cu-Zu-Au mine has resulted in the accumulation of ∼14 Mt of fine-grained tailings at the mouth of the King River, Western Tasmania. The tailings consist primarily of sulfides (<em>i.e.,</em> pyrite, chalcopyrite, molybdenite, galena), silicates, and amorphous phases such as Fe-oxyhydroxides and sulphates. The long-term weathering of these anthropogenic-deltaic sediments has influenced the geochemical distribution and mineralogical hosts of trace metal(loid)s that are of both environmental concern and economic interest (i.e., Cu, Co, Au, Ag, Mo, As). In this study, the mineralogy, element deportment, and metal(loid) enrichment of variably altered delta sediments were investigated to understand how natural weathering processes influenced the environmental mobility and amenability to reprocessing these waste products.</div><div>Micro-scale compositional and textural domains were assessed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), where metal(loid) relationships revealed a complex multi-stage diagenesis within the sediment. Generation of grain-scale geochemical domains through machine learning cluster analysis support the interpretation of in-situ mineralogical growth zones that influence the distribution of trace metal(loid)s. Eight clusters were identified by their unique mineralogical and chemical composition, revealing that metal(loids), initially bound to primary sulfides, have been remobilized and sequestered by authigenic material. This study demonstrates that the complex hydrodynamic and geochemical processes within the delta continue to influence the mobility and long-term stability of legacy contaminants within this deposit. Results demonstrate that machine learning cluster analysis provides a robust tool to understand the distribution of trace metal(loid)s within unconsolidated mining-impacted sediment that have been altered by complex hydrodynamic and geochemical processes. Knowledge generated in this study is relevant for assessing the feasibility of various remediation strategies, including reprocessing of tailings as an alternative management option.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106366"},"PeriodicalIF":3.1,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Mechanistic model for the cotransport of colloids and radionuclides in saturated porous systems based on the interaction forces between colloids","authors":"Qi Tan ,&nbsp;Qingfeng Tang ,&nbsp;Xinyi Shi ,&nbsp;Hongjie Zhao ,&nbsp;Shuyang Li ,&nbsp;Yuan Chen ,&nbsp;Xiaoyan Wei ,&nbsp;Zhen Xu ,&nbsp;Duoqiang Pan ,&nbsp;Wangsuo Wu","doi":"10.1016/j.apgeochem.2025.106381","DOIUrl":"10.1016/j.apgeochem.2025.106381","url":null,"abstract":"<div><div>The presence of colloids in groundwater can enhance radionuclide transport by adsorbing them. In general, colloid transport dominates the process of cotransport. Ripening and site-blocking are two common behaviors in the colloid transport process that are essentially affected by intercolloid forces. In this work, a finite difference model was constructed to describe the cotransport behaviors of radionuclides and colloids in saturated porous media by focusing on the forces between colloids. The proposed model was formulated based on the assumption that the presence of nuclides did not influence colloid transport and ignored the decay of radionuclides in a short period. The one-dimensional advection-dispersion transport of nuclides was coupled with the transport of nuclides in the form of pseudo-colloids. The adsorption and desorption processes of nuclides on media, as well as on mobile or filtered colloids, were considered. Moreover, ripening in the presence of attractive forces between colloids and site-blocking in the presence of repulsive forces between colloids were investigated. The distribution ratios of nuclides in the free solute and in colloidal states during cotransport were reported, and the ripening and site-blocking mechanisms were unified through the force field between colloids. The model was verified by comparing the calculated results with the experimental data. In addition, a parameter sensitivity study was carried out to explore the influence of each parameter on the cotransport process. The model proposed in this paper could be helpful to predict the transport and retention risks of nuclides in porous media containing many colloids.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106381"},"PeriodicalIF":3.1,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746344","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":"Exploring abiotic non-catalytic polyphenol-Maillard humification in light-limited environment","authors":"Afzaal Ashraf ,&nbsp;Wu Haoyu ,&nbsp;Zhang Baijia ,&nbsp;Chu Aodan ,&nbsp;Yang Yue ,&nbsp;Fanping Zhu ,&nbsp;Zhifeng Li ,&nbsp;Shengli Lian ,&nbsp;Zhen Hu ,&nbsp;Yang Zeng","doi":"10.1016/j.apgeochem.2025.106368","DOIUrl":"10.1016/j.apgeochem.2025.106368","url":null,"abstract":"<div><div>Abiotic humification involving polyphenol-maillard precursors leads to the formation of Humic-like substances (HLSs). Previous research has been conducted on catalytic or mineral-associated pathways, although the physicochemical role of noncatalytic abiotic pathway in light-limited environments remains unexplored. Current study investigates the noncatalytic polycondensation reaction between catechol (free polyphenol) and Maillard precursors (glucose &amp; glycine) to synthesize HLSs. In the presence of catechol, singlet oxygen (¹O₂) production solely derived the reaction at mild temperature and light-limited conditions, independent of photochemical or Fenton-type reactions. Spectroscopic analyses revealed a dominant presence of aliphatic moieties, consistent with ultra-high-resolution mass spectrometry (UHRMS) data. Polycondensation reaction released elevated CO₂ levels and decline in pH, indicating aromatic ring cleavage, carboxyl group formation and transformation of aromatics into aliphatic fragments. Additionally, Van Krevelen analysis showed increased O/C ratio in HLS. Notably, the key components included acidic and glucose oxidation products, along with some Maillard reaction intermediates (confirmed with Kendrick Mass analysis). This study provides a novel noncatalytic abiotic humification pathway, corroborating with environments where light-assisted and photochemical processes are minimal such as subsurface soils and underground water.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106368"},"PeriodicalIF":3.1,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725988","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":"Properties of solid bitumen formed during hydrous, anhydrous, and brine pyrolysis of oil shale: Implications for solid bitumen reflectance in source-rock reservoirs","authors":"Paul C. Hackley ,&nbsp;Justin E. Birdwell ,&nbsp;Ryan McAleer","doi":"10.1016/j.apgeochem.2025.106365","DOIUrl":"10.1016/j.apgeochem.2025.106365","url":null,"abstract":"<div><div>Solid bitumen reflectance (BR_o in %) is widely used as a thermal maturity proxy in source-rock reservoirs, yet solid bitumen texture and physical attributes may be affected by varying environmental constraints during its formation, e.g., water saturation, mineral catalysis, or salinity. Herein we investigated the development of solid bitumen properties during artificial maturation using three diverse (lacustrine to marine) oil shale samples containing abundant amorphous H-rich sedimentary organic matter (bituminite). The oil shales were treated via pyrolysis (320 °C, 72 h) using hydrous, anhydrous, and brine conditions, causing the development of a newly formed solid bitumen in the experiment residues from the thermal conversion of bituminite. The properties of the newly formed solid bitumen then were evaluated via geochemical screening tests, optical and electron microscopy, and infrared spectroscopy. Experimental residues also were treated via solvent extraction, allowing characterization of the effects of extraction on solid bitumen. Results showed that bituminite with higher resin and asphaltene components evolved to a solid bitumen with higher reflectance (as a percentage of the original value) when exposed to the same heat treatment, relative to bituminite with higher saturate and aromatic components. Aromatization of solid bitumen also was generally more pronounced in the presence of deionized water relative to anhydrous conditions, supporting prior observations. These results suggest the compositions of primary sedimentary organic matter, and the local concentration of water, affect the development of solid bitumen during thermal advance, potentially explaining the origin of multiple solid bitumen populations with varying reflectance in source-rock reservoir samples or in a single microscope field. Experiments using brine were inconclusive regarding enhanced/decreased aromatization, which could be attributed to the salinities of the brines used in the tests. Extraction of residues caused a consistent increase in BR_o values, suggesting that migrating or expelled oils could cause an increase in BR_o via natural solvation and absent an increase in temperature. This work provides insights into the development and evolution of BR_o in source-rock reservoirs as a function of the composition of the original bituminite and changing environmental conditions, with potentially broad application for petroleum prospecting and resource estimation.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"185 ","pages":"Article 106365"},"PeriodicalIF":3.1,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826356","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}