Pub Date : 2026-01-01DOI: 10.1016/j.oregeorev.2025.107038
Zhenjiang Wang , Chao Wang , Yannan Wang , Zhenmin Jin
The world-class Jinchuan magmatic Ni-Cu sulfide deposit in China represents a globally significant source for nickel (Ni) and platinum-group elements (PGEs). However, the sulfur source and the magmatic evolution responsible for ore formation in the Jinchuan intrusion remain controversial. Field evidence for crustal marble assimilation, along with oxygen fugacity (relative to the fayalite–magnetite–quartz buffer, ΔFMQ) estimates from olivine-spinel (−2.1 – +2.4) and olivine-sulfide oxybarometry (−1.1 – +0.3), suggests a redox transition from reduced to oxidized conditions during early-stage magma evolution. This interpretation is further corroborated by thermodynamic modeling using rhyolite-MELTS. Major element compositional variations within the intrusion, combined with thermodynamic simulations, indicate that magma evolution was dominated by olivine, orthopyroxene, and clinopyroxene crystallization. Our modeling further implies that the lower crustal assimilation, followed by incorporation of ∼ 10 – 15 % marble, played a critical role in the deposit’s formation. NanoSIMS analyses of magmatic sulfide ores reveal a broad δ34S range (−5.3 ‰ to + 4.5 ‰; n = 56). We interpret this variability as resulting from the combined effects of magma redox state transition, magmatic-hydrothermal fluid activity, and potential incorporation of crustal sulfur during the main metallogenic stage. In contrast, Cr-spinel-hosted sulfide inclusions preserve mantle-like sulfur isotope signatures (δ34S = − 2.0 ‰ to + 2.1 ‰; n = 18) and restricted S/Se ratios (2,007 – 4,860). These observations suggest minimal external sulfur contribution during the early differentiation sequence of the Jinchuan parental magma. Numerical modeling reveals that during the redox state transition, the sulfur solubility contrast between magma liquidus and orthopyroxene crystallization temperatures increases dramatically from 0.01 wt% to 0.15 wt% (sulfide saturation), even 0.24 wt% (sulfate saturation). This significant enhancement in sulfur solubility substantially reduces the magma volume required for deposit formation. Collectively, our findings propose that redox state transitions in magmatic systems could serve as a critical mechanism for enhancing the mineralization potential of parental magmas to form Ni-Cu sulfide deposits.
{"title":"In situ sulfur isotopic and thermodynamic constraints on the magmatic evolution and Metallogenesis of the Jinchuan Ni–Cu sulfide Deposit, China","authors":"Zhenjiang Wang , Chao Wang , Yannan Wang , Zhenmin Jin","doi":"10.1016/j.oregeorev.2025.107038","DOIUrl":"10.1016/j.oregeorev.2025.107038","url":null,"abstract":"<div><div>The world-class Jinchuan magmatic Ni-Cu sulfide deposit in China represents a globally significant source for nickel (Ni) and platinum-group elements (PGEs). However, the sulfur source and the magmatic evolution responsible for ore formation in the Jinchuan intrusion remain controversial. Field evidence for crustal marble assimilation, along with oxygen fugacity (relative to the fayalite–magnetite–quartz buffer, ΔFMQ) estimates from olivine-spinel (−2.1 – +2.4) and olivine-sulfide oxybarometry (−1.1 – +0.3), suggests a redox transition from reduced to oxidized conditions during early-stage magma evolution. This interpretation is further corroborated by thermodynamic modeling using rhyolite-MELTS. Major element compositional variations within the intrusion, combined with thermodynamic simulations, indicate that magma evolution was dominated by olivine, orthopyroxene, and clinopyroxene crystallization. Our modeling further implies that the lower crustal assimilation, followed by incorporation of ∼ 10 – 15 % marble, played a critical role in the deposit’s formation. NanoSIMS analyses of magmatic sulfide ores reveal a broad δ<sup>34</sup>S range (−5.3 ‰ to + 4.5 ‰; n = 56). We interpret this variability as resulting from the combined effects of magma redox state transition, magmatic-hydrothermal fluid activity, and potential incorporation of crustal sulfur during the main metallogenic stage. In contrast, Cr-spinel-hosted sulfide inclusions preserve mantle-like sulfur isotope signatures (δ<sup>34</sup>S = − 2.0 ‰ to + 2.1 ‰; n = 18) and restricted S/Se ratios (2,007 – 4,860). These observations suggest minimal external sulfur contribution during the early differentiation sequence of the Jinchuan parental magma. Numerical modeling reveals that during the redox state transition, the sulfur solubility contrast between magma liquidus and orthopyroxene crystallization temperatures increases dramatically from 0.01 wt% to 0.15 wt% (sulfide saturation), even 0.24 wt% (sulfate saturation). This significant enhancement in sulfur solubility substantially reduces the magma volume required for deposit formation. Collectively, our findings propose that redox state transitions in magmatic systems could serve as a critical mechanism for enhancing the mineralization potential of parental magmas to form Ni-Cu sulfide deposits.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"188 ","pages":"Article 107038"},"PeriodicalIF":3.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925510","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 : 2026-01-01DOI: 10.1016/j.oregeorev.2025.107090
Cun Zhang , Fan Yang , Leon Bagas , Xuhuang Zhang , Nan Ma , Xinyi Zhu , Rongbin Zhang
<div><div>The Luanchuan jade deposit in the East Qinling Orogen, central China provides crucial clues to the tectonic evolutionary processes of the southern margin of the North China Block (NCB). The jade is primarily composed of serpentine jade with subordinate associated nephrite/tremolite jade, where the former is distinctly in contact with metamorphosed gabbro. Significant debate remains, however, regarding the jade types’ spatial and temporal distribution and genesis. In this study, we integrate petrography, X-ray powder diffraction, geochemistry, S-Sr isotopes, and zircon U-Pb geochronology to elucidate the mineralogy, mineralisation processes, and tectonic setting of major serpentine jade occurrences. Our findings indicate that the ore bodies primarily underwent serpentine alteration, characterised by the mineral assemblage serpentine (antigorite)–dolomite–calcite–diopside–chlorite–pyrite. Pyrite shows a narrow range of δ<sup>34</sup>S value from 3.4 to 5.6 ‰, coupled with a Co/Ni ratio varying between 1.83 and 12.6, indicative of a magmatic-hydrothermal origin. Whole-rock geochemistry of the jade samples is characterised by a strongly negative Eu anomaly, a slight Ce anomaly, enrichment in light rare earth elements (LREEs), flat heavy rare earth elements (HREEs) patterns, along with significant U and Th enrichments, but depletion in Rb, Ba, Nb, and other trace elements. These characteristics indicate a close genetic link between the serpentine jade and its host dolomitic marble. Geochemical characteristics (Th/U, δU, and δCe ratios) indicate that the jade was formed in an oxidized environment, while the whole-rock Sr/Ba, Zr/Hf, and Nb/Ta ratios depict its formation in an alkaline formation environment. The <sup>87</sup>Sr/<sup>86</sup>Sr values in the jade samples range from 0.706459 to 0.709109, typical of marine Sr components pointing to inheritance from metasedimentary components. Zircon U-Pb dating of the metagabbro yields a concordant age of 860 ± 8 Ma (interpreted as the crystallisation age) revealing a significant mid-Neoproterozoic magmatic event. In contrast, U-Pb dating of metamorphic zircon (with Th/U ratios of 0.02–0.24) from the jade (serpentinised marble) yields an upper intercept age of 1924 ± 14 Ma. The date is interpreted as corresponding to a Paleoproterozoic tectono-thermal event that triggered the regional metamorphism of marine carbonate rocks into dolomitic marble. Integrated geological investigations reveal that the Mg and Ca at the Luanchuan serpentine jade were primarily derived from dolomitic marble. While the sources of SiO<sub>2</sub> and H<sub>2</sub>O were associated with both metamorphic fluids and mafic magmatism, further confirmed by the comparatively close ratios of Eu/Sm and Sm/Nd between the metagabbro and samples of the Luanchuan serpentine jade. Our study emphasizes that the serpentine jade deposit primarily formed through multiple tectonic episodes, during which basic magmatic-hydrothermal fluids int
{"title":"Genesis of the Luanchuan serpentine jade, East Qinling, China: Insights from petrology, geochemistry, and U-Pb geochronology","authors":"Cun Zhang , Fan Yang , Leon Bagas , Xuhuang Zhang , Nan Ma , Xinyi Zhu , Rongbin Zhang","doi":"10.1016/j.oregeorev.2025.107090","DOIUrl":"10.1016/j.oregeorev.2025.107090","url":null,"abstract":"<div><div>The Luanchuan jade deposit in the East Qinling Orogen, central China provides crucial clues to the tectonic evolutionary processes of the southern margin of the North China Block (NCB). The jade is primarily composed of serpentine jade with subordinate associated nephrite/tremolite jade, where the former is distinctly in contact with metamorphosed gabbro. Significant debate remains, however, regarding the jade types’ spatial and temporal distribution and genesis. In this study, we integrate petrography, X-ray powder diffraction, geochemistry, S-Sr isotopes, and zircon U-Pb geochronology to elucidate the mineralogy, mineralisation processes, and tectonic setting of major serpentine jade occurrences. Our findings indicate that the ore bodies primarily underwent serpentine alteration, characterised by the mineral assemblage serpentine (antigorite)–dolomite–calcite–diopside–chlorite–pyrite. Pyrite shows a narrow range of δ<sup>34</sup>S value from 3.4 to 5.6 ‰, coupled with a Co/Ni ratio varying between 1.83 and 12.6, indicative of a magmatic-hydrothermal origin. Whole-rock geochemistry of the jade samples is characterised by a strongly negative Eu anomaly, a slight Ce anomaly, enrichment in light rare earth elements (LREEs), flat heavy rare earth elements (HREEs) patterns, along with significant U and Th enrichments, but depletion in Rb, Ba, Nb, and other trace elements. These characteristics indicate a close genetic link between the serpentine jade and its host dolomitic marble. Geochemical characteristics (Th/U, δU, and δCe ratios) indicate that the jade was formed in an oxidized environment, while the whole-rock Sr/Ba, Zr/Hf, and Nb/Ta ratios depict its formation in an alkaline formation environment. The <sup>87</sup>Sr/<sup>86</sup>Sr values in the jade samples range from 0.706459 to 0.709109, typical of marine Sr components pointing to inheritance from metasedimentary components. Zircon U-Pb dating of the metagabbro yields a concordant age of 860 ± 8 Ma (interpreted as the crystallisation age) revealing a significant mid-Neoproterozoic magmatic event. In contrast, U-Pb dating of metamorphic zircon (with Th/U ratios of 0.02–0.24) from the jade (serpentinised marble) yields an upper intercept age of 1924 ± 14 Ma. The date is interpreted as corresponding to a Paleoproterozoic tectono-thermal event that triggered the regional metamorphism of marine carbonate rocks into dolomitic marble. Integrated geological investigations reveal that the Mg and Ca at the Luanchuan serpentine jade were primarily derived from dolomitic marble. While the sources of SiO<sub>2</sub> and H<sub>2</sub>O were associated with both metamorphic fluids and mafic magmatism, further confirmed by the comparatively close ratios of Eu/Sm and Sm/Nd between the metagabbro and samples of the Luanchuan serpentine jade. Our study emphasizes that the serpentine jade deposit primarily formed through multiple tectonic episodes, during which basic magmatic-hydrothermal fluids int","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"188 ","pages":"Article 107090"},"PeriodicalIF":3.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925786","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 : 2025-12-31DOI: 10.1016/j.oregeorev.2025.107092
Ying Wang , Zhaochong Zhang , Shu Zhang , Zhiguo Cheng , He Huang
Sediment-hosted Zn-Pb deposits are the most important global source of Pb and Zn, yet their genesis and timing remain central questions in economic geology. Direct geochronological constraints are often difficult to obtain due to the general absence of suitable datable minerals, hindering the understanding of ore-forming processes and regional metallogenic models. The Hoxbulak Zn-Pb deposit in Xinjiang, a typical sediment-hosted Zn-Pb deposit in the southwestern Tianshan Mountains of the Central Asian metallogenic domain, has long been controversial with respect to its genetic type and mineralization age, primarily focusing on whether it is related to adjacent Permian magmatism and whether it formed syngenetically or epigenetically. In this study, we conducted precise Sm-Nd isochron dating of sphalerite, galena, and associated calcite/dolomite from the main mineralization stage, yielding a mineralization age of 55 ± 2 Ma. This result indicates that the deposit formed during the Paleogene and shows no genetic relationship with the neighboring Permian Hoxbulak pluton (261.5 ± 2.7 Ma; 273.6 ± 2.0 Ma and 274.8 ± 1.5 Ma), supporting its classification as an epigenetic Mississippi Valley-type (MVT) deposit. Integrated regional structural analysis suggests that this mineralization event was likely controlled by transpression tectonics triggered during the initial India-Eurasia collision (∼60–50 Ma). Our findings demonstrate that the Hoxbulak deposit represents a critical northwestern extension of the Tethyan MVT metallogenic belt (spanning Yunnan-Tibet-Xinjiang) and serves as its easternmost component within the Central Asian metallogenic domain—linking the classic Tethyan MVT system with the interior of the Central Asian Orogenic Belt. This study provides important constraints for exploring Paleogene MVT-type Zn-Pb deposits in Late Paleozoic carbonate formations of the South Tianshan, offering significant insights into the metallogenic patterns of Zn-Pb deposits in the junction zone between the Tethyan and Central Asian orogenic belts.
{"title":"Sm-Nd geochronology of the Hoxbulak Zn-Pb deposit in Xinjiang (NW China) and its link to Paleogene Mississippi Valley-type mineralization in the Tethyan domain","authors":"Ying Wang , Zhaochong Zhang , Shu Zhang , Zhiguo Cheng , He Huang","doi":"10.1016/j.oregeorev.2025.107092","DOIUrl":"10.1016/j.oregeorev.2025.107092","url":null,"abstract":"<div><div>Sediment-hosted Zn-Pb deposits are the most important global source of Pb and Zn, yet their genesis and timing remain central questions in economic geology. Direct geochronological constraints are often difficult to obtain due to the general absence of suitable datable minerals, hindering the understanding of ore-forming processes and regional metallogenic models. The Hoxbulak Zn-Pb deposit in Xinjiang, a typical sediment-hosted Zn-Pb deposit in the southwestern Tianshan Mountains of the Central Asian metallogenic domain, has long been controversial with respect to its genetic type and mineralization age, primarily focusing on whether it is related to adjacent Permian magmatism and whether it formed syngenetically or epigenetically. In this study, we conducted precise Sm-Nd isochron dating of sphalerite, galena, and associated calcite/dolomite from the main mineralization stage, yielding a mineralization age of 55 ± 2 Ma. This result indicates that the deposit formed during the Paleogene and shows no genetic relationship with the neighboring Permian Hoxbulak pluton (261.5 ± 2.7 Ma; 273.6 ± 2.0 Ma and 274.8 ± 1.5 Ma), supporting its classification as an epigenetic Mississippi Valley-type (MVT) deposit. Integrated regional structural analysis suggests that this mineralization event was likely controlled by transpression tectonics triggered during the initial India-Eurasia collision (∼60–50 Ma). Our findings demonstrate that the Hoxbulak deposit represents a critical northwestern extension of the Tethyan MVT metallogenic belt (spanning Yunnan-Tibet-Xinjiang) and serves as its easternmost component within the Central Asian metallogenic domain—linking the classic Tethyan MVT system with the interior of the Central Asian Orogenic Belt. This study provides important constraints for exploring Paleogene MVT-type Zn-Pb deposits in Late Paleozoic carbonate formations of the South Tianshan, offering significant insights into the metallogenic patterns of Zn-Pb deposits in the junction zone between the Tethyan and Central Asian orogenic belts.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"189 ","pages":"Article 107092"},"PeriodicalIF":3.6,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039412","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 : 2025-12-28DOI: 10.1016/j.oregeorev.2025.107085
Liang Li , Shucheng Tan , Zheng Liu , Jingxian Meng , Jianyu Yang , Yuguo Zhou , Xiaohu He , Jiang Zhu , Hailong He , Qinghe Yan , Hui Ye
As a representative deposit of indium (indium)-rich skarn mineralization systems, the Dulong world-class Sn-Zn-In deposit offers an ideal natural laboratory for investigating the occurrence patterns, spatial distribution, and substitution mechanisms of indium through systematic in-situ analysis using EPMA and LA-ICP-MS. Our analytical results reveal significant and selective enrichment of indium in minerals, governed by complex substitution mechanisms. Indium preferentially concentrates in sphalerite, cassiterite, and chalcopyrite, while other minerals (e.g., magnetite, arsenopyrite, and pyrrhotite) exhibit anomalously elevated indium contents. However, the predominance of sphalerite in the deposit inhibits the formation of discrete indium mineral phases. The incorporation of indium primarily occurs through isomorphic substitution involving multiple coupled mechanisms, including: (i) (Cu, Ag)+ + In3+ ↔ 2(Zn, Fe)2+ in sphalerite and chalcopyrite; (ii) In3+ ↔ Fe3+ in cassiterite and chalcopyrite; (iii) In3+ + Sn4+ ↔ Fe2+ + (Nb, Ta)5+ in cassiterite; (iv) Ag+ + Sn2+ + In3+ ↔ 3Zn2+ in chalcopyrite. During skarn mineralization processes, the distribution and enrichment of indium are principally controlled by four key factors: (i) crystallographic constraints of host minerals, (ii) physicochemical properties of ore-forming fluids, (iii) thermodynamic conditions, and (iv) specific substitution mechanisms. Indium preferentially partitions into minerals with tetrahedral coordination sites and those formed under high-temperature conditions. Furthermore, sulfur-rich hydrothermal systems with elevated sulfur fugacity demonstrate enhanced indium enrichment capacity. Temporally, indium enrichment exhibits distinct stage-specific characteristics, with principal concentration occurring in oxide-stage cassiterite and early sulfide-stage Fe-rich sphalerite and chalcopyrite developed under high sulfur fugacity conditions. We provide critical insights into the microscale occurrence states and atomic-scale substitution mechanisms of indium in the Dulong deposit. By systematically elucidating the geochemical behavior and enrichment processes of indium during skarn mineralization, our findings advance the understanding of critical metal enrichment mechanisms and expand the theoretical framework of skarn deposit formation.
{"title":"Indium distribution and substitution mechanisms in the skarn mineralization process of world-class Dulong Sn–Zn–In deposit, Yunnan Province (Southwest China)","authors":"Liang Li , Shucheng Tan , Zheng Liu , Jingxian Meng , Jianyu Yang , Yuguo Zhou , Xiaohu He , Jiang Zhu , Hailong He , Qinghe Yan , Hui Ye","doi":"10.1016/j.oregeorev.2025.107085","DOIUrl":"10.1016/j.oregeorev.2025.107085","url":null,"abstract":"<div><div>As a representative deposit of indium (indium)-rich skarn mineralization systems, the Dulong world-class Sn-Zn-In deposit offers an ideal natural laboratory for investigating the occurrence patterns, spatial distribution, and substitution mechanisms of indium through systematic <em>in-situ</em> analysis using EPMA and LA-ICP-MS. Our analytical results reveal significant and selective enrichment of indium in minerals, governed by complex substitution mechanisms. Indium preferentially concentrates in sphalerite, cassiterite, and chalcopyrite, while other minerals (e.g., magnetite, arsenopyrite, and pyrrhotite) exhibit anomalously elevated indium contents. However, the predominance of sphalerite in the deposit inhibits the formation of discrete indium mineral phases. The incorporation of indium primarily occurs through isomorphic substitution involving multiple coupled mechanisms, including: (i) (Cu, Ag)<sup>+</sup> + In<sup>3+</sup> ↔ 2(Zn, Fe)<sup>2+</sup> in sphalerite and chalcopyrite; (ii) In<sup>3+</sup> ↔ Fe<sup>3+</sup> in cassiterite and chalcopyrite; (iii) In<sup>3+</sup> + Sn<sup>4+</sup> ↔ Fe<sup>2+</sup> + (Nb, Ta)<sup>5+</sup> in cassiterite; (iv) Ag<sup>+</sup> + Sn<sup>2+</sup> + In<sup>3+</sup> ↔ 3Zn<sup>2+</sup> in chalcopyrite. During skarn mineralization processes, the distribution and enrichment of indium are principally controlled by four key factors: (i) crystallographic constraints of host minerals, (ii) physicochemical properties of ore-forming fluids, (iii) thermodynamic conditions, and (iv) specific substitution mechanisms. Indium preferentially partitions into minerals with tetrahedral coordination sites and those formed under high-temperature conditions. Furthermore, sulfur-rich hydrothermal systems with elevated sulfur fugacity demonstrate enhanced indium enrichment capacity. Temporally, indium enrichment exhibits distinct stage-specific characteristics, with principal concentration occurring in oxide-stage cassiterite and early sulfide-stage Fe-rich sphalerite and chalcopyrite developed under high sulfur fugacity conditions. We provide critical insights into the microscale occurrence states and atomic-scale substitution mechanisms of indium in the Dulong deposit. By systematically elucidating the geochemical behavior and enrichment processes of indium during skarn mineralization, our findings advance the understanding of critical metal enrichment mechanisms and expand the theoretical framework of skarn deposit formation.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"189 ","pages":"Article 107085"},"PeriodicalIF":3.6,"publicationDate":"2025-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039407","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 : 2025-12-18DOI: 10.1016/j.oregeorev.2025.107073
Zhengyuan Jia, Luofan Xiong, Gang Zhang, Guibin Zhang
In deep-seated and concealed mineral exploration, variations in ore-forming systems lead to significant differences in geophysical responses, driven by contrasting structural and petrophysical characteristics. For instance, epithermal deposits typically occur as veins or disseminated bodies, and their scale, geometry, and spatial distribution strongly influence gravity and magnetic anomalies. Consequently, single-method geophysical approaches often fail to accurately delineate prospecting targets. This study investigates the Shuangjianzishan ore district in southeastern Inner Mongolia, China, using a combination of multi-scale edge detection and 3D gravity and magnetic inversion to analyze ore-forming processes and assess mineral prospectivity. Laboratory measurements of rock physical properties were used to establish quantitative relationships between density and magnetic susceptibility, providing a foundation for lithological discrimination. Multi-scale edge detection revealed structural boundaries and ore-controlling faults at various depths. The three-dimensional density and susceptibility models derived from the inversion of gravity and magnetic data, when integrated with petrophysical statistical analysis, enabled the identification of key lithological units such as ore-hosting strata and intrusive rocks. A 3D lithological model was constructed, from which a conceptual epithermal mineralization model was derived to guide exploration targeting. The results show that major structural boundaries align with known faults, and the inversion models correlate well with confirmed ore bodies. Several delineated prospective zones coincide with known mineralization, confirming the reliability of the proposed method. Additionally, five previously unidentified high-potential zones were recognized. This study enhances the understanding of the genesis of the Shuangjianzishan deposit and offers an effective technical framework for exploring similar concealed epithermal systems in the southeastern Greater Khingan Range.
{"title":"Integrated gravity and magnetic data for epithermal deposit target area identification: A case study from the Shuangjianzishan Region, Inner Mongolia","authors":"Zhengyuan Jia, Luofan Xiong, Gang Zhang, Guibin Zhang","doi":"10.1016/j.oregeorev.2025.107073","DOIUrl":"10.1016/j.oregeorev.2025.107073","url":null,"abstract":"<div><div>In deep-seated and concealed mineral exploration, variations in ore-forming systems lead to significant differences in geophysical responses, driven by contrasting structural and petrophysical characteristics. For instance, epithermal deposits typically occur as veins or disseminated bodies, and their scale, geometry, and spatial distribution strongly influence gravity and magnetic anomalies. Consequently, single-method geophysical approaches often fail to accurately delineate prospecting targets. This study investigates the Shuangjianzishan ore district in southeastern Inner Mongolia, China, using a combination of multi-scale edge detection and 3D gravity and magnetic inversion to analyze ore-forming processes and assess mineral prospectivity. Laboratory measurements of rock physical properties were used to establish quantitative relationships between density and magnetic susceptibility, providing a foundation for lithological discrimination. Multi-scale edge detection revealed structural boundaries and ore-controlling faults at various depths. The three-dimensional density and susceptibility models derived from the inversion of gravity and magnetic data, when integrated with petrophysical statistical analysis, enabled the identification of key lithological units such as ore-hosting strata and intrusive rocks. A 3D lithological model was constructed, from which a conceptual epithermal mineralization model was derived to guide exploration targeting. The results show that major structural boundaries align with known faults, and the inversion models correlate well with confirmed ore bodies. Several delineated prospective zones coincide with known mineralization, confirming the reliability of the proposed method. Additionally, five previously unidentified high-potential zones were recognized. This study enhances the understanding of the genesis of the Shuangjianzishan deposit and offers an effective technical framework for exploring similar concealed epithermal systems in the southeastern Greater Khingan Range.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"188 ","pages":"Article 107073"},"PeriodicalIF":3.6,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787257","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 : 2025-12-15DOI: 10.1016/j.oregeorev.2025.107066
Salman Farahani, Abbas Bahroudi
As easily exploitable near-surface orebodies become progressively depleted, exploration is increasingly shifting toward deeper and structurally complex settings where concealed mineral systems dominate. This study introduces a multi-scale 3D CNN-Transformer architecture augmented with attention mechanisms for high-resolution volumetric mineral prospectivity modelling. The framework seamlessly integrates diverse geological, geophysical, and geochemical datasets into a unified voxel grid, with multi-scale 3D convolutions capturing localised mineralization signatures and a Transformer encoder modelling long-range subsurface dependencies. Applied to the Siahcheshmeh intrusion-related gold deposit in northwest Iran, the model generated detailed 3D prospectivity volumes and achieved excellent predictive performance (mean ROC-AUC = 0.94). Model-guided drill targeting intersected gold-bearing intervals in approximately 82 % of exploratory boreholes, representing a substantial improvement over conventional success rates. Attention-weighted visualizations further enhanced geological interpretability by clearly highlighting the structural and geochemical controls on ore formation. Although the approach markedly improves target ranking and offers considerable potential for reducing drilling expenditure and environmental footprint, its success remains contingent on high-quality input data and sufficient computational resources. We discuss current limitations and propose pathways for extending the framework to other deposit styles and multimodal datasets.
{"title":"3D mineral prospectivity modeling using a multi-scale CNN–transformer: A case study from the Siahcheshmeh gold deposit, NW Iran","authors":"Salman Farahani, Abbas Bahroudi","doi":"10.1016/j.oregeorev.2025.107066","DOIUrl":"10.1016/j.oregeorev.2025.107066","url":null,"abstract":"<div><div>As easily exploitable near-surface orebodies become progressively depleted, exploration is increasingly shifting toward deeper and structurally complex settings where concealed mineral systems dominate. This study introduces a multi-scale 3D CNN-Transformer architecture augmented with attention mechanisms for high-resolution volumetric mineral prospectivity modelling. The framework seamlessly integrates diverse geological, geophysical, and geochemical datasets into a unified voxel grid, with multi-scale 3D convolutions capturing localised mineralization signatures and a Transformer encoder modelling long-range subsurface dependencies. Applied to the Siahcheshmeh intrusion-related gold deposit in northwest Iran, the model generated detailed 3D prospectivity volumes and achieved excellent predictive performance (mean ROC-AUC = 0.94). Model-guided drill targeting intersected gold-bearing intervals in approximately 82 % of exploratory boreholes, representing a substantial improvement over conventional success rates. Attention-weighted visualizations further enhanced geological interpretability by clearly highlighting the structural and geochemical controls on ore formation. Although the approach markedly improves target ranking and offers considerable potential for reducing drilling expenditure and environmental footprint, its success remains contingent on high-quality input data and sufficient computational resources. We discuss current limitations and propose pathways for extending the framework to other deposit styles and multimodal datasets.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"189 ","pages":"Article 107066"},"PeriodicalIF":3.6,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981792","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 : 2025-12-14DOI: 10.1016/j.oregeorev.2025.107062
Jianjun Zhang , Zeyi Chen , Min Shen , Lei Gao , Ting Chen , Bowen Nie , Yuanchang Fu
The Baihua’ao fluorite deposit is a typical fluorite deposit closely related to granite in central Hunan Province. In order to clarify its mineralization age and process, this paper conducted research on whole rock geochemistry, fluid inclusions, H-O isotopes, and Sm-Nd, Rb-Sr, and U-Pb isotope geochronology. The zircon U-Pb isotope geochronology and SiO2-K2O, A/CNK-A/NK, (K2O + Na2O)/CaO-10000 × Ga/Al, TFeO/MgO-10000 × Ga/Al, Y-Nb-Ce, and Y-Nb-3 Ga diagrams of granite indicate that the granite is a high-potassium peraluminous A-type granite, formed at 213.6 Ma (Late Triassic), and belongs to the post-orogenic tectonic setting related to the Indosinian movement. The fluid inclusions and H-O isotopes of fluorite indicate that the ore-forming fluid is mainly atmospheric precipitation. The Rb-Sr and Sm-Nd isotope geochronology and rare earth element studies of fluorite show that the mineralization age of fluorite is 145.7–147.6 Ma, with green and purple fluorite formed during the early mineralization period and white fluorite formed during the late mineralization period. The Sm/Nd ratio and (La + Y)-(Y/La) diagram of fluorite indicate that the ore-forming material is closely related to the surrounding rock. The Tb/Ca-Tb/La diagram and inclusion characteristics of fluorite indicate that water–rock interaction is the main mineralization mechanism, followed by a decrease in fluid temperature.
{"title":"Geochemistry, inclusions, isotope geochemistry, and isotope chronology of the Baihua’ao fluorite deposit in central Hunan Province: constraints on the timing and process of mineralization","authors":"Jianjun Zhang , Zeyi Chen , Min Shen , Lei Gao , Ting Chen , Bowen Nie , Yuanchang Fu","doi":"10.1016/j.oregeorev.2025.107062","DOIUrl":"10.1016/j.oregeorev.2025.107062","url":null,"abstract":"<div><div>The Baihua’ao fluorite deposit is a typical fluorite deposit closely related to granite in central Hunan Province. In order to clarify its mineralization age and process, this paper conducted research on whole rock geochemistry, fluid inclusions, H-O isotopes, and Sm-Nd, Rb-Sr, and U-Pb isotope geochronology. The zircon U-Pb isotope geochronology and SiO<sub>2</sub>-K<sub>2</sub>O, A/CNK-A/NK, (K<sub>2</sub>O + Na<sub>2</sub>O)/CaO-10000 × Ga/Al, TFeO/MgO-10000 × Ga/Al, Y-Nb-Ce, and Y-Nb-3 Ga diagrams of granite indicate that the granite is a high-potassium peraluminous A-type granite, formed at 213.6 Ma (Late Triassic), and belongs to the post-orogenic tectonic setting related to the Indosinian movement. The fluid inclusions and H-O isotopes of fluorite indicate that the ore-forming fluid is mainly atmospheric precipitation. The Rb-Sr and Sm-Nd isotope geochronology and rare earth element studies of fluorite show that the mineralization age of fluorite is 145.7–147.6 Ma, with green and purple fluorite formed during the early mineralization period and white fluorite formed during the late mineralization period. The Sm/Nd ratio and (La + Y)-(Y/La) diagram of fluorite indicate that the ore-forming material is closely related to the surrounding rock. The Tb/Ca-Tb/La diagram and inclusion characteristics of fluorite indicate that water–rock interaction is the main mineralization mechanism, followed by a decrease in fluid temperature.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"188 ","pages":"Article 107062"},"PeriodicalIF":3.6,"publicationDate":"2025-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787282","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 : 2025-12-13DOI: 10.1016/j.oregeorev.2025.107049
Nynke Keulen, Benjamin Heredia, Diogo R.N. Rosa, Sebastian N. Malkki, Tonny B. Thomsen, David Whitehead
Efficient mineral exploration requires early tailoring to target deposit types. Mineral assemblages of 12 different W-Sn occurrences in the East-Greenland Caledonides with scheelite and cassiterite were investigated with automated quantitative mineralogy on SEM and for their trace elements with LA-ICPMS and integrated observations were correlated through statistical analyses on literature data. Results indicate that scheelite and cassiterite trace element geochemistry can differentiate between skarn, greisen, and quartz-scheelite vein deposit types. The mineralization processes are influenced enough by specific geological settings and fluid compositions to allow for the differentiation of deposit types from mineral trace element geochemistry. These data assist in understanding complex geological histories and varied mineralization processes in the East-Greenland Caledonides. U-Pb dating of scheelite, apatite and cassiterite of samples from multiple locations reveal three distinct mineralization pulses around 425 Ma, 400 Ma, and 370 Ma, the first two linked to magmatic fluids and finally a third metamorphic fluid phase. Analyses also suggest that the scheelite closure temperature lies in the same range as the one for apatite. This approach supports more efficient and effective exploration strategies by improving the understanding of the timing and nature of mineralization events in the East-Greenland Caledonides.
{"title":"Fingerprinting W-Sn mineralization processes in the East Greenland Caledonides using scheelite and cassiterite U-Pb dating and trace element composition","authors":"Nynke Keulen, Benjamin Heredia, Diogo R.N. Rosa, Sebastian N. Malkki, Tonny B. Thomsen, David Whitehead","doi":"10.1016/j.oregeorev.2025.107049","DOIUrl":"10.1016/j.oregeorev.2025.107049","url":null,"abstract":"<div><div>Efficient mineral exploration requires early tailoring to target deposit types. Mineral assemblages of 12 different W-Sn occurrences in the East-Greenland Caledonides with scheelite and cassiterite were investigated with automated quantitative mineralogy on SEM and for their trace elements with LA-ICPMS and integrated observations were correlated through statistical analyses on literature data. Results indicate that scheelite and cassiterite trace element geochemistry can differentiate between skarn, greisen, and quartz-scheelite vein deposit types. The mineralization processes are influenced enough by specific geological settings and fluid compositions to allow for the differentiation of deposit types from mineral trace element geochemistry. These data assist in understanding complex geological histories and varied mineralization processes in the East-Greenland Caledonides. U-Pb dating of scheelite, apatite and cassiterite of samples from multiple locations reveal three distinct mineralization pulses around 425 Ma, 400 Ma, and 370 Ma, the first two linked to magmatic fluids and finally a third metamorphic fluid phase. Analyses also suggest that the scheelite closure temperature lies in the same range as the one for apatite. This approach supports more efficient and effective exploration strategies by improving the understanding of the timing and nature of mineralization events in the East-Greenland Caledonides.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"189 ","pages":"Article 107049"},"PeriodicalIF":3.6,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145950228","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}
The Jiaodong Peninsula, located in the eastern North China Craton (NCC), constitutes the province with the third-highest gold output worldwide. Previous studies show that granitoids from this region were mainly emplaced in the Archean and Mesozoic whereas granites of other ages are scarce. These constraints pose challenges to elucidating the magmatic evolution and metallogenic processes that occurred throughout the formation and destruction of the NCC. To address these problems, the granites of the Jiudian gold deposit in the northern Jiaodong Peninsula were, for the first time, systematically examined using whole-rock major and trace element geochemistry combined with in situ zircon trace element analyses. The Jiudian granitoids, including biotite monzogranite and granitic gneiss, are metaluminous to weakly peraluminous, belonging to the high-K calc-alkaline series and exhibiting enrichment in large-ion lithophile elements and high-field strength elements with weak negative Eu anomalies. Nonetheless, zircon trace element analyses show that granites of distinct ages are characterized by notable disparities in oxygen fugacity, with the Neoproterozoic granite displaying higher oxidation state (ΔFMQ = 1.82 to 4.56) than the Late Jurassic granites and the zircon xenocrysts of Mesoarchean to Paleoproterozoic ages. The present work additionally shows that the Jurassic granites from the Jiudian deposit share broadly similar oxidation conditions with other Linglong-type granites, which corresponds to the values reported for the Guojialing- and Weideshan-type granites from the Jiaodong Peninsula. Comparison of trace element compositions between Neoproterozoic zircons from the Jiudian granitic gneiss and inherited zircons within the Linglong-type granites reveals close geochemical similarities, implying that the inherited Neoproterozoic zircons in the Mesozoic granites likely originated from Neoproterozoic wall rocks within the NCC rather than from the Yangtze Craton. Our results provide direct evidence for the existence of Neoproterozoic magmatism in the eastern NCC and highlight its significance in understanding crustal evolution and the metallogenic framework of the Jiaodong gold province.
{"title":"Geochemical constraints on the petrogenesis of the Neoproterozoic and Late Jurassic granitoids from the Jiudian gold deposit, Jiaodong Peninsula, North China Craton","authors":"Jinghui Niu , Minggang Wu , Dunfang Qiu , Fuquan Tian , Zichong Song , Dejiang Fan , Pengrui Lv , Daoxue Xu , Shihua Zhong","doi":"10.1016/j.oregeorev.2025.107065","DOIUrl":"10.1016/j.oregeorev.2025.107065","url":null,"abstract":"<div><div>The Jiaodong Peninsula, located in the eastern North China Craton (NCC), constitutes the province with the third-highest gold output worldwide. Previous studies show that granitoids from this region were mainly emplaced in the Archean and Mesozoic whereas granites of other ages are scarce. These constraints pose challenges to elucidating the magmatic evolution and metallogenic processes that occurred throughout the formation and destruction of the NCC. To address these problems, the granites of the Jiudian gold deposit in the northern Jiaodong Peninsula were, for the first time, systematically examined using whole-rock major and trace element geochemistry combined with in situ zircon trace element analyses. The Jiudian granitoids, including biotite monzogranite and granitic gneiss, are metaluminous to weakly peraluminous, belonging to the high-K calc-alkaline series and exhibiting enrichment in large-ion lithophile elements and high-field strength elements with weak negative Eu anomalies. Nonetheless, zircon trace element analyses show that granites of distinct ages are characterized by notable disparities in oxygen fugacity, with the Neoproterozoic granite displaying higher oxidation state (ΔFMQ = 1.82 to 4.56) than the Late Jurassic granites and the zircon xenocrysts of Mesoarchean to Paleoproterozoic ages. The present work additionally shows that the Jurassic granites from the Jiudian deposit share broadly similar oxidation conditions with other Linglong-type granites, which corresponds to the values reported for the Guojialing- and Weideshan-type granites from the Jiaodong Peninsula. Comparison of trace element compositions between Neoproterozoic zircons from the Jiudian granitic gneiss and inherited zircons within the Linglong-type granites reveals close geochemical similarities, implying that the inherited Neoproterozoic zircons in the Mesozoic granites likely originated from Neoproterozoic wall rocks within the NCC rather than from the Yangtze Craton. Our results provide direct evidence for the existence of Neoproterozoic magmatism in the eastern NCC and highlight its significance in understanding crustal evolution and the metallogenic framework of the Jiaodong gold province.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"188 ","pages":"Article 107065"},"PeriodicalIF":3.6,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787281","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 : 2025-12-12DOI: 10.1016/j.oregeorev.2025.107060
Albertus J.B. Smith , Dillan Fitton , Clarisa Vorster , Ronny Schoenberg
The ∼2.4 Ga Hotazel Formation of the Transvaal Supergroup of South Africa marks the oldest major chemical sedimentary Mn accumulation and hosts the largest known land-based Mn deposit on Earth. Its age places it in temporal proximity to the Great Oxidation Event (GOE), potentially making its deposition a major paleoenvironmental event. However, the extent t to which it records a local versus a global event remains unclear. This paper assesses the stratigraphy, mineralogy and geochemistry of an unaltered drill core intersection of the Hotazel Formation close to the southern limit of the region.
The stratigraphy in the study area is typical of the broader region. It is marked by three depositional cycles of banded Fe formation (BIF), hematite lutite (HL) and Mn formation (MnF). The observed sedimentology indicates that the Fe to Mn to Fe depositional cycles correspond to sea-level rise and fall, with the BIFs generally deposited in shallower water than the MnFs. Quartz and most Fe-Mn-rich oxides and silicates appear to be early diagenetic whereas the 13C-depleted carbonates and coarser magnetite are paragenetically later. The implication is that all minerals, except for quartz, greenalite and stilpnomelane, formed from Fe3+- and Mn3+/4+-oxyhydroxide precursors.
The Fe and Mn were most likely sourced as Fe2+ and Mn2+ from low-temperature hydrothermal plumes in a deeper, reduced water column. The main mode of deposition was the biologically mediated oxidation of Fe2+ and Mn2+ in shallower, oxygenated waters, implying that it is a biogenic deposit. The formed Fe3+- and Mn3+/4+-oxyhydroxides selectively scavenged different trace elements depending on the surface charge of their stable ligands, forming the trace element patterns observed in this study. Fe oxidation would have needed to reach near completion before Mn oxidation could proceed.
The results imply that the Hotazel Formation was deposited in a semi-restricted basin with inverted bathymetry. Both a continental shelf with an offshore barrier and a continental back-arc basin would be suitable depositional settings to account for most of the features. A major implication is that the Hotazel Formation might have recorded an isolated, unique depositional setting rather than a global paleoenvironmental signature. It also implies that for land-based sedimentary Mn deposits the tectonic setting, basin architecture and chemical sedimentology are the critical exploration vectors rather than the age of the sedimentary sequence.
南非德兰士瓦超群的~ 2.4 Ga Hotazel组标志着最古老的主要化学沉积Mn积累，并拥有地球上已知最大的陆基Mn矿床。它的年龄使它在时间上接近大氧化事件（GOE），这可能使它的沉积成为一个主要的古环境事件。然而，它记录本地事件与全球事件的程度仍不清楚。。本文对靠近本区南缘的Hotazel组未变质岩心交点进行了地层学、矿物学和地球化学评价。研究区内的地层是该区的典型。以带状铁（BIF）、赤铁矿（HL）和锰（MnF）三个沉积旋回为标志。沉积学观测表明，Fe - Mn - Fe沉积旋回与海平面上升和下降相对应，bif一般沉积在较浅的水域。石英和大多数富铁锰氧化物和硅酸盐表现为早成岩作用，而贫13c碳酸盐和粗磁铁矿则表现为晚共生作用。结果表明，除石英、绿绿石和石蜡外，其余矿物均由Fe3+-和Mn3+/4+-氢氧前体形成。铁和锰极有可能来源于深层还原水柱中的低温热液柱中的Fe2+和Mn2+。沉积物的主要沉积模式是生物介导的Fe2+和Mn2+在较浅的含氧水域的氧化，这意味着它是一个生物沉积。形成的Fe3+-和Mn3+/4+-氧氢氧化物根据其稳定配体的表面电荷选择性清除不同的微量元素，形成本研究中观察到的微量元素模式。铁的氧化需要接近完成，锰的氧化才能进行。研究结果表明，该组沉积于半受限盆地。具有近海屏障的大陆架和大陆弧后盆地都是适合的沉积环境，可以解释大部分特征。一个主要的暗示是，霍塔泽尔组可能记录了一个孤立的、独特的沉积环境，而不是一个全球性的古环境标志。对于陆基沉积型锰矿来说，构造环境、盆地构型和化学沉积学是勘探的关键载体，而不是沉积层序的年龄。
{"title":"The iron and manganese formations of the Paleoproterozoic Hotazel Formation in the southern Kalahari Manganese Field of South Africa: Paleoenvironmental and depositional implications at the onset of the Great Oxidation Event","authors":"Albertus J.B. Smith , Dillan Fitton , Clarisa Vorster , Ronny Schoenberg","doi":"10.1016/j.oregeorev.2025.107060","DOIUrl":"10.1016/j.oregeorev.2025.107060","url":null,"abstract":"<div><div>The ∼2.4 Ga Hotazel Formation of the Transvaal Supergroup of South Africa marks the oldest major chemical sedimentary Mn accumulation and hosts the largest known land-based Mn deposit on Earth. Its age places it in temporal proximity to the Great Oxidation Event (GOE), potentially making its deposition a major paleoenvironmental event. However, the extent t to which it records a local versus a global event remains unclear. This paper assesses the stratigraphy, mineralogy and geochemistry of an unaltered drill core intersection of the Hotazel Formation close to the southern limit of the region.</div><div>The stratigraphy in the study area is typical of the broader region. It is marked by three depositional cycles of banded Fe formation (BIF), hematite lutite (HL) and Mn formation (MnF). The observed sedimentology indicates that the Fe to Mn to Fe depositional cycles correspond to sea-level rise and fall, with the BIFs generally deposited in shallower water than the MnFs. Quartz and most Fe-Mn-rich oxides and silicates appear to be early diagenetic whereas the <sup>13</sup>C-depleted carbonates and coarser magnetite are paragenetically later. The implication is that all minerals, except for quartz, greenalite and stilpnomelane, formed from Fe<sup>3+</sup>- and Mn<sup>3+/4+</sup>-oxyhydroxide precursors.</div><div>The Fe and Mn were most likely sourced as Fe<sup>2+</sup> and Mn<sup>2+</sup> from low-temperature hydrothermal plumes in a deeper, reduced water column. The main mode of deposition was the biologically mediated oxidation of Fe<sup>2+</sup> and Mn<sup>2+</sup> in shallower, oxygenated waters, implying that it is a biogenic deposit. The formed Fe<sup>3+</sup>- and Mn<sup>3+/4+</sup>-oxyhydroxides selectively scavenged different trace elements depending on the surface charge of their stable ligands, forming the trace element patterns observed in this study. Fe oxidation would have needed to reach near completion before Mn oxidation could proceed.</div><div>The results imply that the Hotazel Formation was deposited in a semi-restricted basin with inverted bathymetry. Both a continental shelf with an offshore barrier and a continental back-arc basin would be suitable depositional settings to account for most of the features. A major implication is that the Hotazel Formation might have recorded an isolated, unique depositional setting rather than a global paleoenvironmental signature. It also implies that for land-based sedimentary Mn deposits the tectonic setting, basin architecture and chemical sedimentology are the critical exploration vectors rather than the age of the sedimentary sequence.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"188 ","pages":"Article 107060"},"PeriodicalIF":3.6,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787266","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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