Pub Date : 2026-03-01Epub Date: 2025-12-27DOI: 10.1016/j.gexplo.2025.107965
Xianyi Huang , Ke Xiao , Changhai Luo , Xiaosheng Cui , Jiale Wang , Xiang Sun
Understanding the mechanisms of gold micro-enrichment is critical for resolving ore-forming processes in orogenic gold systems. The Qinglonggou deposit, on the northern margin of the Qaidam Basin (NMQB), has long been debated with respect to its genesis and gold enrichment. We combine ore microscopy with in situ trace-element analyses of sulfides to address this problem. LA-ICP-MS data show that early pyrite (Py1) hosts the highest concentrations of Au, Sb, Ag, and Te, which decrease systematically from Py1 to Py3. Arsenopyrite contains 1–2 orders of magnitude higher concentrations of most ore-forming elements than coeval pyrite, reflecting abundant As lattice sites and structural defects that enhance incorporation of Au and chalcophile elements. All sulfide generations display a positive AuAs correlation, consistent with As-driven invisible‑gold solid solution, whereas arsenopyrite exhibits a negative AuSb correlation, implying that high Sb contents reduce its capacity to host Au. Trace-element systematics indicate derivation from a single evolving fluid that cooled progressively, underwent boiling during stage I and II, and became stable and depleted at stage III. Precipitation of visible gold during stage II was mainly associated with extensive Sb incorporation into arsenopyrite.
{"title":"Geological characteristics and gold enrichment mechanism of the Qinglonggou gold deposit in the northern margin of the Qaidam Basin","authors":"Xianyi Huang , Ke Xiao , Changhai Luo , Xiaosheng Cui , Jiale Wang , Xiang Sun","doi":"10.1016/j.gexplo.2025.107965","DOIUrl":"10.1016/j.gexplo.2025.107965","url":null,"abstract":"<div><div>Understanding the mechanisms of gold micro-enrichment is critical for resolving ore-forming processes in orogenic gold systems. The Qinglonggou deposit, on the northern margin of the Qaidam Basin (NMQB), has long been debated with respect to its genesis and gold enrichment. We combine ore microscopy with in situ trace-element analyses of sulfides to address this problem. LA-ICP-MS data show that early pyrite (Py1) hosts the highest concentrations of Au, Sb, Ag, and Te, which decrease systematically from Py1 to Py3. Arsenopyrite contains 1–2 orders of magnitude higher concentrations of most ore-forming elements than coeval pyrite, reflecting abundant As lattice sites and structural defects that enhance incorporation of Au and chalcophile elements. All sulfide generations display a positive Au<img>As correlation, consistent with As-driven invisible‑gold solid solution, whereas arsenopyrite exhibits a negative Au<img>Sb correlation, implying that high Sb contents reduce its capacity to host Au. Trace-element systematics indicate derivation from a single evolving fluid that cooled progressively, underwent boiling during stage I and II, and became stable and depleted at stage III. Precipitation of visible gold during stage II was mainly associated with extensive Sb incorporation into arsenopyrite.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107965"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-23DOI: 10.1016/j.gexplo.2025.107963
Maria Vaňková , Aleš Vaněk , Anastasiia Shalabai , Martin Mihaljevič , Vojtěch Ettler , Martin Racek , Petr Drahota , Petr Fleissig , Petra Vokurková , Tereza Zádorová , Vít Penížek , Tomáš Hrdlička , Ryan Mathur
This study presents silver (Ag) stable isotope ratios (expressed as δ109Ag) combined with mineralogy and speciation data in Ag-contaminated anthropogenic soils from a historic mining area at Kutná Hora, Czech Republic. Results showed large variability of soil Ag, both in concentrations (~0.5–100 mg/kg) and isotopic patterns (δ109Ag from −0.5 to +1.2 ‰, ±0.1 ‰ 2σ), resulting from differences in the source substrates, i.e. the composition of the original mining waste or slag. In other words, the data do not reflect the fractionation of Ag isotopes during pedogenesis and weathering processes, but rather the inherited 109Ag/107Ag signature of the hydrothermal ore and its genesis history. Examining our endmembers and their potential quantities, a tendency for soils to become isotopically lighter (depleted in the heavy 109Ag isotope) as the concentration of Ag increases was identified, and vice versa. This finding suggests that Ag-rich sulfides, primarily galena, generally favor the light 107Ag isotope over Ag-poor phases being enriched in the heavy isotope (109Ag). Given the negligible post-depositional isotopic effects and the overall high stability of Ag in the studied soils, it is theorized that Ag isotopes can serve as sensitive indicators for monitoring the origin and nature of Ag-containing sulfides and their weathering products. From a general contamination perspective, which is important on many levels, the Ag isotopic and concentration data demonstrate the following: (i) the low mass migration of Ag, and (ii) the well-preserved Ag isotopic patterns in ancient anthropogenic soils (≤17th century).
{"title":"Silver is immobile in Ag-rich mine waste: Isotopic evidence from anthropogenic soils","authors":"Maria Vaňková , Aleš Vaněk , Anastasiia Shalabai , Martin Mihaljevič , Vojtěch Ettler , Martin Racek , Petr Drahota , Petr Fleissig , Petra Vokurková , Tereza Zádorová , Vít Penížek , Tomáš Hrdlička , Ryan Mathur","doi":"10.1016/j.gexplo.2025.107963","DOIUrl":"10.1016/j.gexplo.2025.107963","url":null,"abstract":"<div><div>This study presents silver (Ag) stable isotope ratios (expressed as δ<sup>109</sup>Ag) combined with mineralogy and speciation data in Ag-contaminated anthropogenic soils from a historic mining area at Kutná Hora, Czech Republic. Results showed large variability of soil Ag, both in concentrations (~0.5–100 mg/kg) and isotopic patterns (δ<sup>109</sup>Ag from −0.5 to +1.2 ‰, ±0.1 ‰ 2σ), resulting from differences in the source substrates, i.e. the composition of the original mining waste or slag. In other words, the data do not reflect the fractionation of Ag isotopes during pedogenesis and weathering processes, but rather the inherited <sup>109</sup>Ag/<sup>107</sup>Ag signature of the hydrothermal ore and its genesis history. Examining our endmembers and their potential quantities, a tendency for soils to become isotopically lighter (depleted in the heavy <sup>109</sup>Ag isotope) as the concentration of Ag increases was identified, and <em>vice versa</em>. This finding suggests that Ag-rich sulfides, primarily galena, generally favor the light <sup>107</sup>Ag isotope over Ag-poor phases being enriched in the heavy isotope (<sup>109</sup>Ag). Given the negligible post-depositional isotopic effects and the overall high stability of Ag in the studied soils, it is theorized that Ag isotopes can serve as sensitive indicators for monitoring the origin and nature of Ag-containing sulfides and their weathering products. From a general contamination perspective, which is important on many levels, the Ag isotopic and concentration data demonstrate the following: (i) the low mass migration of Ag, and (ii) the well-preserved Ag isotopic patterns in ancient anthropogenic soils (≤17th century).</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107963"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-22DOI: 10.1016/j.gexplo.2025.107964
Yang Lan , Yan Li , Ke Liu , Long Chen , Haoran Huang , Xinyu Cheng , Zi Ye , Yujie Jiang , Meixian Wang
Heavy metal contamination in urban soils poses a significant threat to sustainable development and public health. Therefore, a systematic evaluation of the sources and risks of heavy metals in urban soils is essential. This study applies an improved Nemerow index, the matter-element extension model, and a Monte Carlo-based health risk model. In addition, it integrates lead isotope analysis, correlation analysis, Self-Organising Maps (SOM), Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR), and the MixSIAR isotopic mixing model. These methods are combined to enable accurate source apportionment and source-specific risk assessment. The results indicate that the high-value zones of all eight heavy metals are mainly distributed in the south-eastern part of the city. The overall ecological risk remains at a controllable level. Carcinogenic and non-carcinogenic risks for adults are negligible, whereas those for children reach 27.30 % and 3.14 %, respectively. Lead-isotope signatures indicate that coal combustion and traffic emissions are the principal sources of lead in soil. Source-health risk analysis suggests that coal combustion is likely an important contributor to overall pollution, with arsenic (As, a metalloid) and its coal-related inputs likely warranting greater attention in control strategies. Children appear to be a more vulnerable group requiring targeted protection. This study provides policy recommendations for preventing and controlling soil pollution in Lanzhou. It also bridges the gap in precise source identification and source-based risk assessment for urban soils.
{"title":"Isotopic tracing of lead for source-specific probabilistic health risk assessment of heavy metals in soils of Lanzhou, China","authors":"Yang Lan , Yan Li , Ke Liu , Long Chen , Haoran Huang , Xinyu Cheng , Zi Ye , Yujie Jiang , Meixian Wang","doi":"10.1016/j.gexplo.2025.107964","DOIUrl":"10.1016/j.gexplo.2025.107964","url":null,"abstract":"<div><div>Heavy metal contamination in urban soils poses a significant threat to sustainable development and public health. Therefore, a systematic evaluation of the sources and risks of heavy metals in urban soils is essential. This study applies an improved Nemerow index, the matter-element extension model, and a Monte Carlo-based health risk model. In addition, it integrates lead isotope analysis, correlation analysis, Self-Organising Maps (SOM), Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR), and the MixSIAR isotopic mixing model. These methods are combined to enable accurate source apportionment and source-specific risk assessment. The results indicate that the high-value zones of all eight heavy metals are mainly distributed in the south-eastern part of the city. The overall ecological risk remains at a controllable level. Carcinogenic and non-carcinogenic risks for adults are negligible, whereas those for children reach 27.30 % and 3.14 %, respectively. Lead-isotope signatures indicate that coal combustion and traffic emissions are the principal sources of lead in soil. Source-health risk analysis suggests that coal combustion is likely an important contributor to overall pollution, with arsenic (As, a metalloid) and its coal-related inputs likely warranting greater attention in control strategies. Children appear to be a more vulnerable group requiring targeted protection. This study provides policy recommendations for preventing and controlling soil pollution in Lanzhou. It also bridges the gap in precise source identification and source-based risk assessment for urban soils.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107964"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-15DOI: 10.1016/j.gexplo.2025.107959
Amirreza Bitaraf , Reza Ghezelbash
This study presents an advanced and reproducible geochemical targeting workflow that integrates multiple unsupervised machine learning algorithms with multifractal modeling to improve early-stage prospectivity analysis in greenfield terrains. We evaluate and systematically compare DBSCAN, Self-Organizing Maps (SOM), and K-series clustering (K-means, K-medians, and K-medoids) using 800 stream-sediment samples from the Hashtjin district located in the Urumieh–Dokhtar Magmatic Belt (UDMB), NW Iran—an important region for porphyry-epithermal copper systems. To address the inherent closed-nature problem in compositional geochemical data, Isometric Log-Ratio (ILR) transformation was applied to ensure valid multivariate analysis, and the BoxCox transformation was subsequently used for normalizing purposes. Multi-fractal CN modeling was then employed to derive anomaly thresholds and delineate anomalous sample catchment basins (SCBs). PCA detected a strong Cu–Au–Mo–As correlation reflecting porphyry-style mineralization, and these elements were used as inputs for clustering.
DBSCAN, optimized using the Silhouette index (ε = 0.110, MinPts = 2), demonstrated the best performance by accurately defining coherent spatial anomalies and effectively distinguishing noise, with the highest success-rate and AUC values among all tested algorithms. SOM captured element-zoning patterns associated with alteration halos, while K-series methods showed lower reliability due to sensitivity to outliers and skewed value distributions. A novel about the weighted-hybrid integration of DBSCAN and SOM and K-Series methods was developed to combine spatial robustness with multivariate pattern recognition. This hybrid approach significantly reduced the initial ~2500 km2 study area to ~1.85 % for very strong anomalies and ~ 12 % when including strong anomalies—representing an efficient regional screening scale for prioritizing follow-up surveys. Therefore, three high-priority target zones were identified: (1) a southeastern zone near the Gollujeh Cu ± Au occurrence with strong geochemical and structural–subvolcanic controls, (2) a central-northern CuMo prospective zone associated with intrusive contacts, and (3) scattered anomalies aligned with fault-controlled hydrothermal pathways. The spatial agreement of anomalies with magmatic units, major faults, and hydrothermal alteration strengthens the exploration significance of the results. This study highlights the effectiveness of a transparent and repeatable unsupervised learning workflow for geochemical exploration in data-limited regions, providing a valuable decision-support tool for future prospectivity modeling across similar metallogenic belts worldwide.
{"title":"Evaluation of SOM, DBSCAN, and K-series clustering algorithms for CuAu anomaly exploration in sample catchment basins: A case study from Hashtjin district, NW Iran","authors":"Amirreza Bitaraf , Reza Ghezelbash","doi":"10.1016/j.gexplo.2025.107959","DOIUrl":"10.1016/j.gexplo.2025.107959","url":null,"abstract":"<div><div>This study presents an advanced and reproducible geochemical targeting workflow that integrates multiple unsupervised machine learning algorithms with multifractal modeling to improve early-stage prospectivity analysis in greenfield terrains. We evaluate and systematically compare DBSCAN, Self-Organizing Maps (SOM), and K-series clustering (K-means, K-medians, and K-medoids) using 800 stream-sediment samples from the Hashtjin district located in the Urumieh–Dokhtar Magmatic Belt (UDMB), NW Iran—an important region for porphyry-epithermal copper systems. To address the inherent closed-nature problem in compositional geochemical data, Isometric Log-Ratio (ILR) transformation was applied to ensure valid multivariate analysis, and the BoxCox transformation was subsequently used for normalizing purposes. Multi-fractal C<img>N modeling was then employed to derive anomaly thresholds and delineate anomalous sample catchment basins (SCBs). PCA detected a strong Cu–Au–Mo–As correlation reflecting porphyry-style mineralization, and these elements were used as inputs for clustering.</div><div>DBSCAN, optimized using the Silhouette index (ε = 0.110, MinPts = 2), demonstrated the best performance by accurately defining coherent spatial anomalies and effectively distinguishing noise, with the highest success-rate and AUC values among all tested algorithms. SOM captured element-zoning patterns associated with alteration halos, while K-series methods showed lower reliability due to sensitivity to outliers and skewed value distributions. A novel about the weighted-hybrid integration of DBSCAN and SOM and K-Series methods was developed to combine spatial robustness with multivariate pattern recognition. This hybrid approach significantly reduced the initial ~2500 km<sup>2</sup> study area to ~1.85 % for very strong anomalies and ~ 12 % when including strong anomalies—representing an efficient regional screening scale for prioritizing follow-up surveys. Therefore, three high-priority target zones were identified: (1) a southeastern zone near the Gollujeh Cu ± Au occurrence with strong geochemical and structural–subvolcanic controls, (2) a central-northern Cu<img>Mo prospective zone associated with intrusive contacts, and (3) scattered anomalies aligned with fault-controlled hydrothermal pathways. The spatial agreement of anomalies with magmatic units, major faults, and hydrothermal alteration strengthens the exploration significance of the results. This study highlights the effectiveness of a transparent and repeatable unsupervised learning workflow for geochemical exploration in data-limited regions, providing a valuable decision-support tool for future prospectivity modeling across similar metallogenic belts worldwide.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107959"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-02DOI: 10.1016/j.gexplo.2025.107966
Hongtao Zhao , Liuan Duan , Yu Zhang , Xiaomeng Han , Yongjun Shao , Yuanming Pan , Yuzhou Feng , Xu Wang , Shuling Song , Hongjie Shen
The Jiaodong Peninsula is a globally significant region for lode gold deposits, characterized by disseminated-stockwork mineralization and auriferous quartz-sulfide vein, but recently-discovered auriferous carbonate-sulfide vein mineralization exhibits considerable exploration potential. This study investigates the Qianchuiliu carbonate-sulfide vein gold deposit (13.5 t @ 3.02 g/t) in Jiaodong. It is characterized by three mineralization stages: quartz-K-feldspar (Stage I), dolomite-polymetallic sulfide-native gold stage (Stage II, the primary mineralization stage), and quartz-calcite (Stage III). Integrated SWIR spectral analysis and petrographic observations indicate that the Qianchuiliu deposit contains white micas (58.7 %), carbonates (35.1 %), and chlorites (6.1 %) as predominant alteration minerals. The illite crystallinity (IC) value of white micas is spatially associated with gold mineralization, with IC values ≥1.2 serving as a reliable exploration indicator. Conversely, the Al-OH absorption peak wavelength (Pos2200) of white micas shows a weak spatial correlation with orebodies. On this basis, a three-dimensional parameter model identifies the northern zone at depths of −300 to −400 m in the mining area as a priority exploration target. Regional comparisons show differences in white mica spectral parameters among disseminated-stockwork, quartz-sulfide vein, and carbonate-sulfide vein deposits, effectively distinguished using partial least squares discriminant analysis (PLS-DA). The most significant spectral parameter is white mica Pos2200 (VIP > 1.5), reflecting variations in their forming physicochemical conditions such as pH and oxygen fugacity. This study develops a SWIR-based exploration indicator system for carbonate-sulfide vein gold deposits, highlighting the effectiveness of spectral parameters in identifying mineralization and differentiating deposit types.
{"title":"Optimizing short-wave infrared (SWIR) indications of alteration minerals for deep mineralization exploration in the Qianchuiliu lode gold deposit, Jiaodong Peninsula","authors":"Hongtao Zhao , Liuan Duan , Yu Zhang , Xiaomeng Han , Yongjun Shao , Yuanming Pan , Yuzhou Feng , Xu Wang , Shuling Song , Hongjie Shen","doi":"10.1016/j.gexplo.2025.107966","DOIUrl":"10.1016/j.gexplo.2025.107966","url":null,"abstract":"<div><div>The Jiaodong Peninsula is a globally significant region for lode gold deposits, characterized by disseminated-stockwork mineralization and auriferous quartz-sulfide vein, but recently-discovered auriferous carbonate-sulfide vein mineralization exhibits considerable exploration potential. This study investigates the Qianchuiliu carbonate-sulfide vein gold deposit (13.5 t @ 3.02 g/t) in Jiaodong. It is characterized by three mineralization stages: quartz-K-feldspar (Stage I), dolomite-polymetallic sulfide-native gold stage (Stage II, the primary mineralization stage), and quartz-calcite (Stage III). Integrated SWIR spectral analysis and petrographic observations indicate that the Qianchuiliu deposit contains white micas (58.7 %), carbonates (35.1 %), and chlorites (6.1 %) as predominant alteration minerals. The illite crystallinity (IC) value of white micas is spatially associated with gold mineralization, with IC values ≥1.2 serving as a reliable exploration indicator. Conversely, the Al-OH absorption peak wavelength (Pos2200) of white micas shows a weak spatial correlation with orebodies. On this basis, a three-dimensional parameter model identifies the northern zone at depths of −300 to −400 m in the mining area as a priority exploration target. Regional comparisons show differences in white mica spectral parameters among disseminated-stockwork, quartz-sulfide vein, and carbonate-sulfide vein deposits, effectively distinguished using partial least squares discriminant analysis (PLS-DA). The most significant spectral parameter is white mica Pos2200 (VIP > 1.5), reflecting variations in their forming physicochemical conditions such as pH and oxygen fugacity. This study develops a SWIR-based exploration indicator system for carbonate-sulfide vein gold deposits, highlighting the effectiveness of spectral parameters in identifying mineralization and differentiating deposit types.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107966"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pyrite, a prevalent mineral in gold deposits, records valuable information about fluid evolution and physicochemical conditions through its textures and composition. The Xiaoyingpan Au deposit in the North China Craton, characterized by multistage mineralization and deformation, provides an ideal setting to investigate these processes. This study integrates electron back-scattered diffraction (EBSD), trace element analysis, and S isotopes to decipher the paragenesis of three pyrite generations (Py1, Py2, Py3) and their implications for fluid evolution and gold endowment at Xiaoyingpan. Petrographic and EBSD results reveal that euhedral Py1 underwent plastic deformation and was subsequently altered to porous and inclusion-rich Py2 via deformation-assisted coupled dissolution-reprecipitation (CDR) reactions. Foam-like Py3 aggregates formed by deformation-induced dynamic recrystallization of Py1. Trace element compositions demonstrate contrasting behaviors during CDR and deformation: lattice-bound elements (Co, Ni) remained immobile, while inclusion-hosted elements (Au, Ag, Te, Cu, Pb) were extensively remobilized and enriched in Py2b domains, highlighting the critical role of deformation microstructures in controlling element redistribution. Consistent S isotope values across all pyrite types suggest a homogeneous S source, with later fluids primarily remobilizing pre-existing metals. We propose a multi-fluid model wherein a metal-rich fluid precipitated Py1 with tellurides and native gold, establishing the primary mineralization. Subsequent reactive and metal-poor fluids drove the dissolution-reprecipitation (forming Py2) and recrystallization (forming Py3) of Py1, respectively, modifying textures and locally upgrading gold grades without introducing significant new metals. This study highlights the importance of EBSD and trace element analyses to decipher formation mechanisms of complex textures in pyrite, which can be used to reveal mineralization and overprinting events in Au deposits.
{"title":"Mobilization of trace elements associated with deformation of pyrite from the Xiaoyingpan Au deposit, North China: Implications for fluid evolution and gold mineralization","authors":"Dazhao Wang , Chaojian Qin , Shimin Zhen , Cheng-Biao Leng","doi":"10.1016/j.gexplo.2025.107954","DOIUrl":"10.1016/j.gexplo.2025.107954","url":null,"abstract":"<div><div>Pyrite, a prevalent mineral in gold deposits, records valuable information about fluid evolution and physicochemical conditions through its textures and composition. The Xiaoyingpan Au deposit in the North China Craton, characterized by multistage mineralization and deformation, provides an ideal setting to investigate these processes. This study integrates electron back-scattered diffraction (EBSD), trace element analysis, and S isotopes to decipher the paragenesis of three pyrite generations (Py1, Py2, Py3) and their implications for fluid evolution and gold endowment at Xiaoyingpan. Petrographic and EBSD results reveal that euhedral Py1 underwent plastic deformation and was subsequently altered to porous and inclusion-rich Py2 via deformation-assisted coupled dissolution-reprecipitation (CDR) reactions. Foam-like Py3 aggregates formed by deformation-induced dynamic recrystallization of Py1. Trace element compositions demonstrate contrasting behaviors during CDR and deformation: lattice-bound elements (Co, Ni) remained immobile, while inclusion-hosted elements (Au, Ag, Te, Cu, Pb) were extensively remobilized and enriched in Py2b domains, highlighting the critical role of deformation microstructures in controlling element redistribution. Consistent S isotope values across all pyrite types suggest a homogeneous S source, with later fluids primarily remobilizing pre-existing metals. We propose a multi-fluid model wherein a metal-rich fluid precipitated Py1 with tellurides and native gold, establishing the primary mineralization. Subsequent reactive and metal-poor fluids drove the dissolution-reprecipitation (forming Py2) and recrystallization (forming Py3) of Py1, respectively, modifying textures and locally upgrading gold grades without introducing significant new metals. This study highlights the importance of EBSD and trace element analyses to decipher formation mechanisms of complex textures in pyrite, which can be used to reveal mineralization and overprinting events in Au deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107954"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-04DOI: 10.1016/j.gexplo.2025.107955
Thais Caroline Murer , Carlos Roberto de Souza Filho
The P-REE-Th Nolans Bore deposit is located in the Northern Territory of Australia and is one of the few known deposits where rare earth elements (REE) are hosted in monomineralic fluorapatite veins. The formation of these REE-fluorapatite veins occurred due to the interaction of carbonatite magma with granulite facies rocks during the peak of metamorphism. In this study, we utilized spectral data from the visible to shortwave infrared (VNIR-SWIR) region, collected at specific points along the drill core, to identify diagnostic parameters of REE host minerals. These data, combined with geochemical analysis, allowed us to estimate the total concentration of rare earth elements (TREE) in the deposit rocks. Our results demonstrated that absorption features indicative of REE could be detected at wavelengths of 580, 744, 804, and 872 nm. Reflectance spectroscopy confirmed the presence of REE in the fluorapatite veins and rocks rich in kaolinite and smectite. Machine learning models were tested to predict TREE concentrations from spectral data. Among the tested models, PLSR and LightGBM achieved comparable overall accuracy, though LightGBM provided more reliable interval predictions. The Multiple-instance learning (MIL) model exhibited higher dispersion, particularly at intermediate TREE values. These findings suggest that reflectance spectroscopy, in conjunction with geochemical data and machine learning algorithms, can be employed to develop models for quantifying REE based on a sample's spectral signature. The predictions made by this model can help determine the spatial distribution of ore content throughout drill cores, reducing reliance on large samples for geochemical testing and decreasing the time required for core analysis.
{"title":"VNIR-SWIR Spectroscopy and Machine Learning: A new approach for Rare Earth Element detection and quantification in fluorapatite veins (Nolans Bore Deposit, Australia)","authors":"Thais Caroline Murer , Carlos Roberto de Souza Filho","doi":"10.1016/j.gexplo.2025.107955","DOIUrl":"10.1016/j.gexplo.2025.107955","url":null,"abstract":"<div><div>The P-REE-Th Nolans Bore deposit is located in the Northern Territory of Australia and is one of the few known deposits where rare earth elements (REE) are hosted in monomineralic fluorapatite veins. The formation of these REE-fluorapatite veins occurred due to the interaction of carbonatite magma with granulite facies rocks during the peak of metamorphism. In this study, we utilized spectral data from the visible to shortwave infrared (VNIR-SWIR) region, collected at specific points along the drill core, to identify diagnostic parameters of REE host minerals. These data, combined with geochemical analysis, allowed us to estimate the total concentration of rare earth elements (TREE) in the deposit rocks. Our results demonstrated that absorption features indicative of REE could be detected at wavelengths of 580, 744, 804, and 872 nm. Reflectance spectroscopy confirmed the presence of REE in the fluorapatite veins and rocks rich in kaolinite and smectite. Machine learning models were tested to predict TREE concentrations from spectral data. Among the tested models, PLSR and LightGBM achieved comparable overall accuracy, though LightGBM provided more reliable interval predictions. The Multiple-instance learning (MIL) model exhibited higher dispersion, particularly at intermediate TREE values. These findings suggest that reflectance spectroscopy, in conjunction with geochemical data and machine learning algorithms, can be employed to develop models for quantifying REE based on a sample's spectral signature. The predictions made by this model can help determine the spatial distribution of ore content throughout drill cores, reducing reliance on large samples for geochemical testing and decreasing the time required for core analysis.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107955"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-08DOI: 10.1016/j.gexplo.2025.107958
Haowei Gu , Xiheng He , Hayden Dalton , Yanshuang Wu , Xiaohua Deng
The Jingerquan rare-metal deposit is the only known pegmatite-type LiBe rare-metal deposit in the Eastern Tianshan. However, the age of Jingerquan deposit remains poorly constrained due to limited studies. In this study we use ArAr and RbSr dating for micas from different pegmatite zones to determine the mineralization age. The electron probe microanalysis (EPMA) results indicate that the chemical composition of muscovite shows a significant variation trend from the barren pegmatite zone to the Li-Be-rich pegmatite zone. Muscovite coexisting with spodumene in the mineralized zone has relatively high contents of Al₂O₃, MnO, Li₂O, and F, whereas muscovite in the barren zone has relatively high contents of FeO and MgO. Other elements such as SiO₂, TiO₂, K₂O, and Na₂O show minor differences in content. Both muscovite and biotite from the barren pegmatite zone are characterized by FeO enrichment. In-situ RbSr dating of muscovite from the barren pegmatite zone yielded an age of 234.2 ± 9.3 Ma (all ages reported to 2σ). The ArAr ages of muscovite in the barren zone are 242.5 ± 0.9 Ma, 242.8 ± 0.8 Ma, 240.9 ± 0.9 Ma and 239.5 ± 1.6 Ma, the ArAr ages of biotite are 239.8 ± 1.0 Ma, 238.6 ± 1.1 Ma, and the muscovite coexisting with spodumene yielded the ArAr ages of 236.3 ± 1.5 Ma and 237.2 ± 1.2 Ma. Through the geochronological study of mica, the metallogenic age of the Jingerquan rare-metal deposit is constrained to approximately 237–236 Ma, while the formation of the pegmatite occurred between 250 and 234 Ma. This study demonstrates that the Jingerquan LiBe rare-metal deposit formed during the Triassic period in a stable intraplate environment through prolonged slow cooling and crystallization.
{"title":"Mica ArAr and in-situ RbSr geochronology for the Jingerquan rare-metal pegmatite deposit, Eastern Tianshan","authors":"Haowei Gu , Xiheng He , Hayden Dalton , Yanshuang Wu , Xiaohua Deng","doi":"10.1016/j.gexplo.2025.107958","DOIUrl":"10.1016/j.gexplo.2025.107958","url":null,"abstract":"<div><div>The Jingerquan rare-metal deposit is the only known pegmatite-type Li<img>Be rare-metal deposit in the Eastern Tianshan. However, the age of Jingerquan deposit remains poorly constrained due to limited studies. In this study we use Ar<img>Ar and Rb<img>Sr dating for micas from different pegmatite zones to determine the mineralization age. The electron probe microanalysis (EPMA) results indicate that the chemical composition of muscovite shows a significant variation trend from the barren pegmatite zone to the Li-Be-rich pegmatite zone. Muscovite coexisting with spodumene in the mineralized zone has relatively high contents of Al₂O₃, MnO, Li₂O, and F, whereas muscovite in the barren zone has relatively high contents of FeO and MgO. Other elements such as SiO₂, TiO₂, K₂O, and Na₂O show minor differences in content. Both muscovite and biotite from the barren pegmatite zone are characterized by FeO enrichment. In-situ Rb<img>Sr dating of muscovite from the barren pegmatite zone yielded an age of 234.2 ± 9.3 Ma (all ages reported to 2σ). The Ar<img>Ar ages of muscovite in the barren zone are 242.5 ± 0.9 Ma, 242.8 ± 0.8 Ma, 240.9 ± 0.9 Ma and 239.5 ± 1.6 Ma, the Ar<img>Ar ages of biotite are 239.8 ± 1.0 Ma, 238.6 ± 1.1 Ma, and the muscovite coexisting with spodumene yielded the Ar<img>Ar ages of 236.3 ± 1.5 Ma and 237.2 ± 1.2 Ma. Through the geochronological study of mica, the metallogenic age of the Jingerquan rare-metal deposit is constrained to approximately 237–236 Ma, while the formation of the pegmatite occurred between 250 and 234 Ma. This study demonstrates that the Jingerquan Li<img>Be rare-metal deposit formed during the Triassic period in a stable intraplate environment through prolonged slow cooling and crystallization.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107958"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-10DOI: 10.1016/j.gexplo.2025.107957
Zhiliang Wang , Xuebing Zhang , Yaochao Sun , Yanjie Geng , Guanghuan Huang , Miaomiao Zhang , Chenlong Li , Zeling Wang
The Wuzunbulake gold deposit, located in the eastern section of the South Tianshan Orogenic Belt, is an important orogenic gold deposit discovered in the southern part of the Kumishi region. Although previous studies have revealed the development of pyrite-sericite alteration proximal to ore bodies in orogenic gold deposits, research on short-wavelength infrared (SWIR) exploration indicators from alteration minerals and its controlling mechanisms remain limited. The Wuzunbulake gold deposit exhibits well-developed host rock alteration. Through microscopic observation and SWIR spectroscopy, 14 alteration minerals, including muscovite, phengite, illite, and chlorite, have been identified. Petrographic observations reveal that muscovite, occurring as coarse-grained scaly aggregates with bright interference colors, predominantly develops in host rocks proximal to the ore bodies. In contrast, phengite occurs as fine-grained aggregates with oriented arrangements in distal metamorphic sandstones. SWIR studies have revealed that muscovite with lower Al-OH (Pos2200) absorption peak values is predominantly developed in mineralized bodies, while phengite with higher Pos2200 is widely distributed across various lithologies. Additionally, the Pos2200 values of the white mica group show negative correlations with AlIV and AlVI, and positive correlations with Si and Fe + Mg. The gold ore bodies of Wuzunbulake gold deposit are spatially consistent with the transition zone from high to low IC values, indicating that gold mineralization occurred in an environment transitioning from high to low temperatures. This is consistent with the geological characteristics of orogenic gold deposits formed within ductile-brittle shear zones. For white mica group minerals, the Pos2200 values of hydrothermal muscovite is lower than the corresponding median values, and can serve as an approximate boundary distinguishing hydrothermal muscovite from metamorphic phengite. The white mica group minerals with Pos2200 ≤ 2216.5 nm (median values for Line 0 and 07 of Zone I) and Pos2200 ≤ 2216.3 nm (median values for Line 31 and 47 of Zone II), and IC values ranging from 7 to 12, can be used as new exploration indicators for the Wuzunbulake gold deposit.
{"title":"Application of white mica minerals to exploration of orogenic gold deposit: A case study of Wuzunbulake gold deposit, South Tianshan (NW China)","authors":"Zhiliang Wang , Xuebing Zhang , Yaochao Sun , Yanjie Geng , Guanghuan Huang , Miaomiao Zhang , Chenlong Li , Zeling Wang","doi":"10.1016/j.gexplo.2025.107957","DOIUrl":"10.1016/j.gexplo.2025.107957","url":null,"abstract":"<div><div>The Wuzunbulake gold deposit, located in the eastern section of the South Tianshan Orogenic Belt, is an important orogenic gold deposit discovered in the southern part of the Kumishi region. Although previous studies have revealed the development of pyrite-sericite alteration proximal to ore bodies in orogenic gold deposits, research on short-wavelength infrared (SWIR) exploration indicators from alteration minerals and its controlling mechanisms remain limited. The Wuzunbulake gold deposit exhibits well-developed host rock alteration. Through microscopic observation and SWIR spectroscopy, 14 alteration minerals, including muscovite, phengite, illite, and chlorite, have been identified. Petrographic observations reveal that muscovite, occurring as coarse-grained scaly aggregates with bright interference colors, predominantly develops in host rocks proximal to the ore bodies. In contrast, phengite occurs as fine-grained aggregates with oriented arrangements in distal metamorphic sandstones. SWIR studies have revealed that muscovite with lower Al-OH (Pos2200) absorption peak values is predominantly developed in mineralized bodies, while phengite with higher Pos2200 is widely distributed across various lithologies. Additionally, the Pos2200 values of the white mica group show negative correlations with Al<sup>IV</sup> and Al<sup>VI</sup>, and positive correlations with Si and Fe + Mg. The gold ore bodies of Wuzunbulake gold deposit are spatially consistent with the transition zone from high to low IC values, indicating that gold mineralization occurred in an environment transitioning from high to low temperatures. This is consistent with the geological characteristics of orogenic gold deposits formed within ductile-brittle shear zones. For white mica group minerals, the Pos2200 values of hydrothermal muscovite is lower than the corresponding median values, and can serve as an approximate boundary distinguishing hydrothermal muscovite from metamorphic phengite. The white mica group minerals with Pos2200 ≤ 2216.5 nm (median values for Line 0 and 07 of Zone I) and Pos2200 ≤ 2216.3 nm (median values for Line 31 and 47 of Zone II), and IC values ranging from 7 to 12, can be used as new exploration indicators for the Wuzunbulake gold deposit.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107957"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-01DOI: 10.1016/j.gexplo.2025.107946
Liangjie Cui , Qihai Shu , Yue He , Di Zhao , Fan Yu , Litian Zhang , Qingfei Wang , Jun Deng
The Yu'erya gold deposit is located in eastern Hebei along the northern margin of the North China Craton, which is one of the typical gold deposits associated with Mesozoic granitic intrusions in the region. A systematic characterization on the gold occurrence and sulfide geochemistry are critical for understanding the mineralization process and guiding recovery strategy. However, such information is still lacking for Yu'erya. In this study, the automated mineralogy mapping using TESCAN Integrated Mineral Analyzer (TIMA) and sulfide compositional determination using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) have been conducted to investigate the gold occurrence and the coupled substitution behavior of Au with other trace elements in pyrite. The results indicate that embedded features of visible gold can be classified as fracture-hosted gold, included gold, and intergranular gold, with fracture-hosted gold being the dominant type, accounting for 57.32 % of the total. Based on the spatial distribution, visible gold is further classified into free gold (spatially independent) and intergrown gold (associated with other minerals), with free gold being the predominant type (67.78 %). In terms of grain size, visible gold can be further divided into four categories: micro-grained gold (1–5 μm), fine-grained gold (5–10 μm), medium-grained gold (10–20 μm), and coarse-grained gold (20–50 μm). Their proportions in terms of area are 8.10 %, 36.45 %, 37.21 %, and 18.24 %, respectively, and by quantity, the corresponding proportions are 38.91 %, 43.52 %, 15.06 %, and 2.51 %. The invisible gold primarily occurs as solid solutions or mineral inclusions, with its content varying among different sulfide minerals. The average concentrations are 0.92 ppm in pyrite, 1.11 ppm in chalcopyrite, and 0.49 ppm in sphalerite. Notably, tetrahedrite exhibits the highest average value (4.17 ppm), occurring exclusively as solid solutions. The Au content shows strong positive correlations with chalcophile elements (Ag, Bi, Cu, Pb, Sb, and Te) in pyrite, strongly indicating that Au-Cu-Sb-Ag-Bi complexes are incorporated into the pyrite lattice through coupled substitution of Fe2+ ions or as micro-mineral inclusions. These findings provide key insights into gold mineralization mechanisms and offer essential mineralogical constraints for ore beneficiation and metallurgical processing.
{"title":"Sulfide geochemistry and gold occurrence in the Yu'erya deposit, Eastern Hebei, China: Implications for mineralization and metallurgy","authors":"Liangjie Cui , Qihai Shu , Yue He , Di Zhao , Fan Yu , Litian Zhang , Qingfei Wang , Jun Deng","doi":"10.1016/j.gexplo.2025.107946","DOIUrl":"10.1016/j.gexplo.2025.107946","url":null,"abstract":"<div><div>The Yu'erya gold deposit is located in eastern Hebei along the northern margin of the North China Craton, which is one of the typical gold deposits associated with Mesozoic granitic intrusions in the region. A systematic characterization on the gold occurrence and sulfide geochemistry are critical for understanding the mineralization process and guiding recovery strategy. However, such information is still lacking for Yu'erya. In this study, the automated mineralogy mapping using TESCAN Integrated Mineral Analyzer (TIMA) and sulfide compositional determination using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) have been conducted to investigate the gold occurrence and the coupled substitution behavior of Au with other trace elements in pyrite. The results indicate that embedded features of visible gold can be classified as fracture-hosted gold, included gold, and intergranular gold, with fracture-hosted gold being the dominant type, accounting for 57.32 % of the total. Based on the spatial distribution, visible gold is further classified into free gold (spatially independent) and intergrown gold (associated with other minerals), with free gold being the predominant type (67.78 %). In terms of grain size, visible gold can be further divided into four categories: micro-grained gold (1–5 μm), fine-grained gold (5–10 μm), medium-grained gold (10–20 μm), and coarse-grained gold (20–50 μm). Their proportions in terms of area are 8.10 %, 36.45 %, 37.21 %, and 18.24 %, respectively, and by quantity, the corresponding proportions are 38.91 %, 43.52 %, 15.06 %, and 2.51 %. The invisible gold primarily occurs as solid solutions or mineral inclusions, with its content varying among different sulfide minerals. The average concentrations are 0.92 ppm in pyrite, 1.11 ppm in chalcopyrite, and 0.49 ppm in sphalerite. Notably, tetrahedrite exhibits the highest average value (4.17 ppm), occurring exclusively as solid solutions. The Au content shows strong positive correlations with chalcophile elements (Ag, Bi, Cu, Pb, Sb, and Te) in pyrite, strongly indicating that Au-Cu-Sb-Ag-Bi complexes are incorporated into the pyrite lattice through coupled substitution of Fe<sup>2+</sup> ions or as micro-mineral inclusions. These findings provide key insights into gold mineralization mechanisms and offer essential mineralogical constraints for ore beneficiation and metallurgical processing.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"282 ","pages":"Article 107946"},"PeriodicalIF":3.3,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145683201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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