Pub Date : 2024-11-16DOI: 10.1016/j.oregeorev.2024.106353
Yue Li , Feng Yuan , Simon M. Jowitt , Xiangling Li , Xiaohui Li , Chaojie Zheng , Taofa Zhou , Yufeng Deng
<div><div>The Xuancheng ore district of eastern China is a newly discovered district within the Middle and Lower Yangtze River Metallogenic Belt (MLYB) that hosts several magmato-hydrothermal related mineral deposits. The Qiaomaishan deposit is a representative example of the skarn deposits within this district and is also the only deposit within the district that hosts tungsten mineralization. However, the source of metals and the hydrothermal evolution of the mineralizing system that formed this deposit remain controversial. This study addresses these issues using new fluid inclusion microthermometric and isotopic data, including fluid inclusion H, quartz O, sulfide S, and pyrite Pb data, which constrain the evolution of the hydrothermal fluids within the system and the source of metal within the Qiaomaishan deposit. This study identified three main stages of hydrothermal evolution and paragenesis within the deposit, namely pre-ore (stage 1), <em>syn</em>-ore (stages 2 and 3), and post-ore formation stages. Stage 1 garnet (andradite)-hosted fluid inclusions homogenize between 390 °C and 590 °C and have salinities of 9–20 wt% NaCl equivalent whereas stage 2 quartz-hosted fluid inclusions homogenize between 200 °C and 460 °C and have salinities of 5–18 wt% NaCl equivalent. Finally, stage 3 quartz- and calcite-hosted fluid inclusions homogenize at temperatures of 120 °C–240 °C and 3–15 wt% NaCl equivalent salinities. The stage 2 quartz has oxygen and hydrogen isotopic compositions (δD<sub>fluid</sub> from −99 ‰ to −57 ‰; δ<sup>18</sup>O<sub>fluid</sub> from 4.0 ‰ to 6.1 ‰) that are close to those expected for magmatic fluids, whereas stage 3 quartz (δD<sub>fluid</sub> from −105 ‰ to −86 ‰; δ<sup>18</sup>O<sub>fluid</sub> from −1.7 to −0.6 ‰) records the mixing of meteoric and hydrothermal magmatic fluids. These fluid inclusion data suggest that cooling was the main mineralizing process involved in stages 1 and 2, and this process may favor the enrichment of tungsten and copper in the residual hydrothermal fluids. In contrast, fluid mixing became increasingly important between stages 2 and 3, leading to a reduction in salinity and temperature as well as changes in fluid isotopic compositions. Water–rock (W/R) interaction is also likely to have been an important process during deposit formation. The δ<sup>34</sup>S (2.7 ‰–5.7 ‰ with a mean of 4.3 ‰) of sulfides from the Qiaomaishan deposit also provide evidence that the sulfur within the deposit has a magmatic origin. The homogeneous pyrite Pb isotopic data (<sup>206/204</sup>Pb = 18.158–18.518, <sup>207/204</sup>Pb = 15.592–15.650, and <sup>208/204</sup>Pb = 36.179–38.634) for samples from the Qiaomaishan deposit further indicates that the metals within the deposit were derived from both mantle and crustal sources. In summary, the Qiaomaishan deposit formed from hydrothermal fluids derived from a magmatic source that subsequently cooled, mixed with meteoric water, and underwent W/R interaction, cau
{"title":"Fluid inclusion and multiple isotope geochemical constraints on the hydrothermal evolution and metal sources of the Qiaomaishan Cu–W skarn deposit, eastern China","authors":"Yue Li , Feng Yuan , Simon M. Jowitt , Xiangling Li , Xiaohui Li , Chaojie Zheng , Taofa Zhou , Yufeng Deng","doi":"10.1016/j.oregeorev.2024.106353","DOIUrl":"10.1016/j.oregeorev.2024.106353","url":null,"abstract":"<div><div>The Xuancheng ore district of eastern China is a newly discovered district within the Middle and Lower Yangtze River Metallogenic Belt (MLYB) that hosts several magmato-hydrothermal related mineral deposits. The Qiaomaishan deposit is a representative example of the skarn deposits within this district and is also the only deposit within the district that hosts tungsten mineralization. However, the source of metals and the hydrothermal evolution of the mineralizing system that formed this deposit remain controversial. This study addresses these issues using new fluid inclusion microthermometric and isotopic data, including fluid inclusion H, quartz O, sulfide S, and pyrite Pb data, which constrain the evolution of the hydrothermal fluids within the system and the source of metal within the Qiaomaishan deposit. This study identified three main stages of hydrothermal evolution and paragenesis within the deposit, namely pre-ore (stage 1), <em>syn</em>-ore (stages 2 and 3), and post-ore formation stages. Stage 1 garnet (andradite)-hosted fluid inclusions homogenize between 390 °C and 590 °C and have salinities of 9–20 wt% NaCl equivalent whereas stage 2 quartz-hosted fluid inclusions homogenize between 200 °C and 460 °C and have salinities of 5–18 wt% NaCl equivalent. Finally, stage 3 quartz- and calcite-hosted fluid inclusions homogenize at temperatures of 120 °C–240 °C and 3–15 wt% NaCl equivalent salinities. The stage 2 quartz has oxygen and hydrogen isotopic compositions (δD<sub>fluid</sub> from −99 ‰ to −57 ‰; δ<sup>18</sup>O<sub>fluid</sub> from 4.0 ‰ to 6.1 ‰) that are close to those expected for magmatic fluids, whereas stage 3 quartz (δD<sub>fluid</sub> from −105 ‰ to −86 ‰; δ<sup>18</sup>O<sub>fluid</sub> from −1.7 to −0.6 ‰) records the mixing of meteoric and hydrothermal magmatic fluids. These fluid inclusion data suggest that cooling was the main mineralizing process involved in stages 1 and 2, and this process may favor the enrichment of tungsten and copper in the residual hydrothermal fluids. In contrast, fluid mixing became increasingly important between stages 2 and 3, leading to a reduction in salinity and temperature as well as changes in fluid isotopic compositions. Water–rock (W/R) interaction is also likely to have been an important process during deposit formation. The δ<sup>34</sup>S (2.7 ‰–5.7 ‰ with a mean of 4.3 ‰) of sulfides from the Qiaomaishan deposit also provide evidence that the sulfur within the deposit has a magmatic origin. The homogeneous pyrite Pb isotopic data (<sup>206/204</sup>Pb = 18.158–18.518, <sup>207/204</sup>Pb = 15.592–15.650, and <sup>208/204</sup>Pb = 36.179–38.634) for samples from the Qiaomaishan deposit further indicates that the metals within the deposit were derived from both mantle and crustal sources. In summary, the Qiaomaishan deposit formed from hydrothermal fluids derived from a magmatic source that subsequently cooled, mixed with meteoric water, and underwent W/R interaction, cau","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106353"},"PeriodicalIF":3.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.oregeorev.2024.106329
Lahiru M.A. Nagasingha , Charles L. Bérubé , Christopher J.M. Lawley
With the increasing demand for raw materials, innovative exploration techniques are needed to discover large mineral deposits that are accessible from the surface. In recent years, various supervised machine learning techniques have proven effective for mineral prospectivity modelling (MPM). However, the successful application of these techniques has been limited due to the scarcity of known mineral deposits compared to barren regions, which leads to a model imbalance favouring the latter. We address the data imbalance challenge in MPM by proposing a novel generative modelling approach using a conditional variational autoencoder (CVAE). We compare the proposed method with two other data balancing techniques, namely the synthetic minority oversampling technique and class weighting. Furthermore, the efficacy of the balancing strategies is evaluated for three MPM classification methods, including extreme gradient boosting machines (XGBM), random forests, and multilayer perceptrons. We implement and test the approaches by modelling the prospectivity of magmatic Ni (±Cu ±Co ±Platinum group elements) sulphide mineral systems for the Canadian landmass. With an area under the success rate curve of 0.95 for a spatially distinct testing data set, we observe that a combination of the proposed CVAE framework with the XGBM classification model surpasses the other methods. Furthermore, the geographical representation of our XGBM-CVAE model demonstrates a strong association with known Ni mineral occurrences in Canada, along with new prospective regions in underexplored areas.
{"title":"A balanced mineral prospectivity model of Canadian magmatic Ni (± Cu ± Co ± PGE) sulphide mineral systems using conditional variational autoencoders","authors":"Lahiru M.A. Nagasingha , Charles L. Bérubé , Christopher J.M. Lawley","doi":"10.1016/j.oregeorev.2024.106329","DOIUrl":"10.1016/j.oregeorev.2024.106329","url":null,"abstract":"<div><div>With the increasing demand for raw materials, innovative exploration techniques are needed to discover large mineral deposits that are accessible from the surface. In recent years, various supervised machine learning techniques have proven effective for mineral prospectivity modelling (MPM). However, the successful application of these techniques has been limited due to the scarcity of known mineral deposits compared to barren regions, which leads to a model imbalance favouring the latter. We address the data imbalance challenge in MPM by proposing a novel generative modelling approach using a conditional variational autoencoder (CVAE). We compare the proposed method with two other data balancing techniques, namely the synthetic minority oversampling technique and class weighting. Furthermore, the efficacy of the balancing strategies is evaluated for three MPM classification methods, including extreme gradient boosting machines (XGBM), random forests, and multilayer perceptrons. We implement and test the approaches by modelling the prospectivity of magmatic Ni (±Cu ±Co ±Platinum group elements) sulphide mineral systems for the Canadian landmass. With an area under the success rate curve of 0.95 for a spatially distinct testing data set, we observe that a combination of the proposed CVAE framework with the XGBM classification model surpasses the other methods. Furthermore, the geographical representation of our XGBM-CVAE model demonstrates a strong association with known Ni mineral occurrences in Canada, along with new prospective regions in underexplored areas.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106329"},"PeriodicalIF":3.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deep-sea sediments highly enriched in rare-earth elements (REEs), termed “REE-rich mud,” have recently attracted attention as a potential mineral resource for industrially critical metals. Previous studies of the geochemistry and mineralogy of REE-rich mud have suggested that the sedimentation rate is key for the formation of REE-rich mud, and, therefore, that Earth system dynamics affecting pelagic sedimentation rates control the formation, ore grade, and distribution of REE-rich mud on a geological time scale. However, the environmental factors controlling the formation of REE-rich mud and their secular variations have never been studied systematically nor quantitatively. In this study, to investigate the dominant factors promoting the formation of REE-rich mud in the Pacific Ocean, we constructed a new multi-box neodymium (Nd) mass balance model that considers interactions between the ocean and seafloor sediments. Sensitivity analysis results showed that dilution by eolian dust, which is not enriched in REEs, results in decreased REE contents in REE-rich mud, whereas the discharge of REEs from the continental margin to the ocean can have a strong positive impact on the REE content of REE-rich mud. Long-term simulations through the Cenozoic demonstrated that dust fluxes dominantly control the secular trend of REE contents in REE-rich mud. The calculated REE content range is consistent with the range observed in data previously reported for North and South Pacific REE-rich mud. However, our model could not reproduce the temporary peaks in REE concentrations observed in actual REE-rich muds. This result implies that such REE peaks reflect local or regional processes, as previously proposed.
{"title":"Long-term variations of factors controlling REE-rich mud formation based on ocean–sediment Nd mass balance modeling","authors":"Ryosuke Matsunami , Kazutaka Yasukawa , Kentaro Nakamura , Yasuhiro Kato","doi":"10.1016/j.oregeorev.2024.106338","DOIUrl":"10.1016/j.oregeorev.2024.106338","url":null,"abstract":"<div><div>Deep-sea sediments highly enriched in rare-earth elements (REEs), termed “REE-rich mud,” have recently attracted attention as a potential mineral resource for industrially critical metals. Previous studies of the geochemistry and mineralogy of REE-rich mud have suggested that the sedimentation rate is key for the formation of REE-rich mud, and, therefore, that Earth system dynamics affecting pelagic sedimentation rates control the formation, ore grade, and distribution of REE-rich mud on a geological time scale. However, the environmental factors controlling the formation of REE-rich mud and their secular variations have never been studied systematically nor quantitatively. In this study, to investigate the dominant factors promoting the formation of REE-rich mud in the Pacific Ocean, we constructed a new multi-box neodymium (Nd) mass balance model that considers interactions between the ocean and seafloor sediments. Sensitivity analysis results showed that dilution by eolian dust, which is not enriched in REEs, results in decreased REE contents in REE-rich mud, whereas the discharge of REEs from the continental margin to the ocean can have a strong positive impact on the REE content of REE-rich mud. Long-term simulations through the Cenozoic demonstrated that dust fluxes dominantly control the secular trend of REE contents in REE-rich mud. The calculated REE content range is consistent with the range observed in data previously reported for North and South Pacific REE-rich mud. However, our model could not reproduce the temporary peaks in REE concentrations observed in actual REE-rich muds. This result implies that such REE peaks reflect local or regional processes, as previously proposed.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106338"},"PeriodicalIF":3.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.oregeorev.2024.106344
Mei-Zhen Yang , Shao-Yong Jiang , Yang-Yang Zhou , Jiang-Li Chen , Shui-Yuan Yang
<div><div>The Laowan deposit is a recently discovered large lode-gold deposit with a Au reserve >208 t in the Tongbai Orogen of Central China. This Au deposit is characterized by the co-occurrence of stockwork-type Mo mineralization. Hydrothermal rutiles are present both in the altered rock-type gold ores and in the alteration halos around the fluorite-K-feldspar-quartz Mo veins. A detailed investigation of the mineralogical, textural, and chemical analyses (EPMA and LA–ICP–MS) of the Au- and Mo-related rutiles was carried out in this study. Au-related rutiles formed during silicification and sericitization, intergrown with a hydrothermal mineral assemblage of pyrite + chalcopyrite + electrum + sericite + quartz + calcite + REEPO<sub>4</sub> minerals, whereas Mo-related rutiles formed during sericitization<!--> <!-->and silicification closely associated with sericite + quartz + apatite + calcite + molybdenite + other Fe-Cu sulfides. Both rutiles formed via hydrothermal breakdown of metamorphic titanites in the host rocks of garnet-epidot-amphoble–quartz schist. The formation mechanism involves coupled dissolution-reprecipitation of CaTiSiO<sub>5</sub> (titanite) + CO<sub>2</sub>-rich fluid = TiO<sub>2</sub> (rutile) + CaCO<sub>3</sub> (calcite) + SiO<sub>2</sub>. The textural features show that most of the Au-related rutiles nucleate and grow at the original textural position of the precursor titanites, suggesting a mechanism of coupled dissolution and in situ precipitation due to relatively low mobility of Ti. The Mo-related rutiles grow in a microenvironment locally enriched in Ti due to the small-scale mobilization of Ti released during titanite dissolution, suggesting a relatively high solubility of Ti. These results indicate that the Mo-mineralized fluid system probably contains more halogens (particularly F) than the Au-mineralized fluid system does because TiO<sub>2</sub> solubility and mobilization increase with increasing halogen concentration in the fluid system. The Au-related rutiles are characterized by enrichment of W, Nb, and Ta, whereas the Mo-related rutiles are characterized by enrichment of Sn, W, and Nb. The mass balance estimation indicated that the Au-related rutiles retained most of the trace elements released from the breakdown of titanites and significantly incorporated W and, to a lesser extent, Nb and Ta from the hydrothermal fluid during rutile precipitation. The Mo-related rutiles incorporated significant amounts of Sn, W, Nb, and, to a lesser extent, Th and Pb from the hydrothermal fluid and Sc, V and Cr from other mafic minerals, such as amphibole, during hydrothermal alteration. The compositional fingerprints of hydrothermal rutiles indicate that the Mo-mineralized fluid contained Sn, W and Nb and more halogen (particularly F), which are distinguished from the Au ore-forming fluid, which contained significant amounts of W but less Nb and Ta and lower amounts of halogen. The Au- and Mo-related rutiles formed from
老湾矿床是最近在华中桐柏造山带发现的一个大型原生金矿床，金储量达 208 吨。该金矿床的特点是同时存在堆积型钼矿化。在蚀变岩型金矿石和萤石-长石-石英钼矿脉周围的蚀变晕中都存在热液金红石。本研究对与金和钼有关的金红石的矿物学、纹理和化学分析（EPMA 和 LA-ICP-MS）进行了详细调查。与金有关的金红石在硅化和绢云母化过程中形成，与黄铁矿+黄铜矿+电黄铜矿+绢云母+石英+方解石+REEPO4矿物的热液矿物组合相互交错；而与钼有关的金红石在绢云母化和硅化过程中形成，与绢云母+石英+磷灰石+方解石+辉钼矿+其他铁-铜硫化物密切相关。这两种金红石都是在石榴石-橄榄石-闪长岩-石英片岩的母岩中通过热液分解变质榍石形成的。形成机制包括 CaTiSiO5（榍石）+富含二氧化碳的流体 = TiO2（金红石）+CaCO3（方解石）+SiO2 的耦合溶解-再沉淀。纹理特征表明，大多数与金有关的金红石都是在前驱体榍石的原始纹理位置成核和生长的，这表明由于钛的流动性相对较低，其机制是溶解和原位沉淀耦合。由于钛铁矿溶解过程中释放的 Ti 的小规模移动，Mo 相关金红石在局部富含 Ti 的微环境中生长，这表明 Ti 的溶解度相对较高。这些结果表明，钼矿化流体体系可能比金矿化流体体系含有更多的卤素（尤其是 F），因为随着流体体系中卤素浓度的增加，TiO2 的溶解度和迁移率也会增加。与金有关的金红石的特点是富含 W、Nb 和 Ta，而与钼有关的金红石的特点是富含 Sn、W 和 Nb。质量平衡估算表明，与金有关的金红石保留了钛铁矿分解过程中释放的大部分微量元素，并在金红石沉淀过程中从热液中大量掺入了W，其次是Nb和Ta。与钼有关的金红石在热液蚀变过程中大量掺入了热液中的锡、钨、铌，少量掺入了热液中的钍和铅，以及闪石等其他黑云母矿物中的锑、钒和铬。热液金红石的成分指纹表明，钼矿化流体含有Sn、W和Nb以及更多的卤素（尤其是F），这与金矿形成流体不同，后者含有大量的W，但Nb和Ta含量较少，卤素含量也较低。与金和钼有关的金红石形成于不同时期（140 Ma ∼和 130 Ma ∼）的两个不同流体系统，记录了同一矿床中两个独立的岩浆-热液流体事件的叠加。
{"title":"Hydrothermal rutile as a pathfinder for discriminating overprinted magmatic-hydrothermal gold and molybdenum mineralization: The giant Laowan Au deposit, Tongbai orogen, Central China","authors":"Mei-Zhen Yang , Shao-Yong Jiang , Yang-Yang Zhou , Jiang-Li Chen , Shui-Yuan Yang","doi":"10.1016/j.oregeorev.2024.106344","DOIUrl":"10.1016/j.oregeorev.2024.106344","url":null,"abstract":"<div><div>The Laowan deposit is a recently discovered large lode-gold deposit with a Au reserve >208 t in the Tongbai Orogen of Central China. This Au deposit is characterized by the co-occurrence of stockwork-type Mo mineralization. Hydrothermal rutiles are present both in the altered rock-type gold ores and in the alteration halos around the fluorite-K-feldspar-quartz Mo veins. A detailed investigation of the mineralogical, textural, and chemical analyses (EPMA and LA–ICP–MS) of the Au- and Mo-related rutiles was carried out in this study. Au-related rutiles formed during silicification and sericitization, intergrown with a hydrothermal mineral assemblage of pyrite + chalcopyrite + electrum + sericite + quartz + calcite + REEPO<sub>4</sub> minerals, whereas Mo-related rutiles formed during sericitization<!--> <!-->and silicification closely associated with sericite + quartz + apatite + calcite + molybdenite + other Fe-Cu sulfides. Both rutiles formed via hydrothermal breakdown of metamorphic titanites in the host rocks of garnet-epidot-amphoble–quartz schist. The formation mechanism involves coupled dissolution-reprecipitation of CaTiSiO<sub>5</sub> (titanite) + CO<sub>2</sub>-rich fluid = TiO<sub>2</sub> (rutile) + CaCO<sub>3</sub> (calcite) + SiO<sub>2</sub>. The textural features show that most of the Au-related rutiles nucleate and grow at the original textural position of the precursor titanites, suggesting a mechanism of coupled dissolution and in situ precipitation due to relatively low mobility of Ti. The Mo-related rutiles grow in a microenvironment locally enriched in Ti due to the small-scale mobilization of Ti released during titanite dissolution, suggesting a relatively high solubility of Ti. These results indicate that the Mo-mineralized fluid system probably contains more halogens (particularly F) than the Au-mineralized fluid system does because TiO<sub>2</sub> solubility and mobilization increase with increasing halogen concentration in the fluid system. The Au-related rutiles are characterized by enrichment of W, Nb, and Ta, whereas the Mo-related rutiles are characterized by enrichment of Sn, W, and Nb. The mass balance estimation indicated that the Au-related rutiles retained most of the trace elements released from the breakdown of titanites and significantly incorporated W and, to a lesser extent, Nb and Ta from the hydrothermal fluid during rutile precipitation. The Mo-related rutiles incorporated significant amounts of Sn, W, Nb, and, to a lesser extent, Th and Pb from the hydrothermal fluid and Sc, V and Cr from other mafic minerals, such as amphibole, during hydrothermal alteration. The compositional fingerprints of hydrothermal rutiles indicate that the Mo-mineralized fluid contained Sn, W and Nb and more halogen (particularly F), which are distinguished from the Au ore-forming fluid, which contained significant amounts of W but less Nb and Ta and lower amounts of halogen. The Au- and Mo-related rutiles formed from","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106344"},"PeriodicalIF":3.2,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.oregeorev.2024.106337
Haoyu Luo , Xu Zheng , Yan Liu
<div><div>More than 600 carbonatites worldwide are spatially and temporally associated with silicate rocks, which contributes to the formation of carbonatite-silicate complexes originating from mantle. However, only a minority of these carbonatites evolve into large to giant rare earth element (REE) deposits. The formation mechanisms of carbonatite-associated REE deposits (CARDs) are primarily attributed to liquid immiscibility. Nonetheless, experimental petrology has discussed the REE distribution coefficients (D<sup>Carb/Sil</sup>) during liquid immiscibility, yet lacks quantification of the difference of the natural deposits. Moreover, the magma source of carbonatites and silicate rocks from these deposits is derived from the mantle, and the geochemical indexes can support further evidence. This study focuses on the globally significant large carbonatite-associated REE deposits, specifically six deposits involving Mianning-Dechang REE belt (Maoniuping, Dalucao, Muluozhai, Lizhuang), Bayan Obo, and Mountain Pass, to investigate the characteristics of the magma source and origin of carbonatite-silicate complexes through bulk-rock geochemistry. The Y/Ho values of carbonatites and silicate rocks from these deposits, except for Lizhaung, are similar to mantle value, indicating a mantle-derived origin. Except for Mountain Pass and Maoniuping carbonatites, high Nb/Ta ratios in the other samples indicate geochemical decoupling during liquid immiscibility, although they have similar charge and ionic radius. To verify the liquid immiscibility, we utilized the discernable geochemical indexes (e.g., Ba/Mn, Ba/La) based on their well-constrained partitioning behaviors in different magma compositions. The results show that the compositions of carbonatites and silicate rocks in Dalucao are strictly accordant with those confirmed by experiments, whereas others deviate more or less. This further suggests that subsequent magma fractionation or fluid-mediated works on the other five deposits and compositionally covers up the evidence of liquid immiscibility. To trace carbonatite-silicate liquid immiscibility in these deposits, we propose the deviation coefficient <em>Ƙ</em> via a comparison on the difference of REE distribution coefficients (D<sup>Carb/Sil</sup>) between experimental results and natural deposits. The examined results show that <em>Ƙ</em> values for Maoniuping, Dalucao, Muluozhai, Bayan Obo Mg-carbonatite and Ca-carbonatite are close to 0, while the <em>Ƙ</em> values for Lizhuang, Bayan Obo Fe-carbonatite and Mountain Pass show the opposite trend. Utilizing the C-O isotopic composition from previous studies and immiscible deviation coefficient <em>Ƙ</em>, the occurrence of immiscibility in Maoniuping, Dalucao, Muluozhai, Bayan Obo Mg-carbonatite and Ca-carbonatite has been confirmed. Based on previous research, we believe that liquid immiscibility not only facilitates pre-enrichment of rare earth elements but also contributes to subsequent REE mi
{"title":"The role of carbonatite-silicate liquid immiscibility in the global large carbonatite-associated REE deposits (CARDs): New insight from the trace element","authors":"Haoyu Luo , Xu Zheng , Yan Liu","doi":"10.1016/j.oregeorev.2024.106337","DOIUrl":"10.1016/j.oregeorev.2024.106337","url":null,"abstract":"<div><div>More than 600 carbonatites worldwide are spatially and temporally associated with silicate rocks, which contributes to the formation of carbonatite-silicate complexes originating from mantle. However, only a minority of these carbonatites evolve into large to giant rare earth element (REE) deposits. The formation mechanisms of carbonatite-associated REE deposits (CARDs) are primarily attributed to liquid immiscibility. Nonetheless, experimental petrology has discussed the REE distribution coefficients (D<sup>Carb/Sil</sup>) during liquid immiscibility, yet lacks quantification of the difference of the natural deposits. Moreover, the magma source of carbonatites and silicate rocks from these deposits is derived from the mantle, and the geochemical indexes can support further evidence. This study focuses on the globally significant large carbonatite-associated REE deposits, specifically six deposits involving Mianning-Dechang REE belt (Maoniuping, Dalucao, Muluozhai, Lizhuang), Bayan Obo, and Mountain Pass, to investigate the characteristics of the magma source and origin of carbonatite-silicate complexes through bulk-rock geochemistry. The Y/Ho values of carbonatites and silicate rocks from these deposits, except for Lizhaung, are similar to mantle value, indicating a mantle-derived origin. Except for Mountain Pass and Maoniuping carbonatites, high Nb/Ta ratios in the other samples indicate geochemical decoupling during liquid immiscibility, although they have similar charge and ionic radius. To verify the liquid immiscibility, we utilized the discernable geochemical indexes (e.g., Ba/Mn, Ba/La) based on their well-constrained partitioning behaviors in different magma compositions. The results show that the compositions of carbonatites and silicate rocks in Dalucao are strictly accordant with those confirmed by experiments, whereas others deviate more or less. This further suggests that subsequent magma fractionation or fluid-mediated works on the other five deposits and compositionally covers up the evidence of liquid immiscibility. To trace carbonatite-silicate liquid immiscibility in these deposits, we propose the deviation coefficient <em>Ƙ</em> via a comparison on the difference of REE distribution coefficients (D<sup>Carb/Sil</sup>) between experimental results and natural deposits. The examined results show that <em>Ƙ</em> values for Maoniuping, Dalucao, Muluozhai, Bayan Obo Mg-carbonatite and Ca-carbonatite are close to 0, while the <em>Ƙ</em> values for Lizhuang, Bayan Obo Fe-carbonatite and Mountain Pass show the opposite trend. Utilizing the C-O isotopic composition from previous studies and immiscible deviation coefficient <em>Ƙ</em>, the occurrence of immiscibility in Maoniuping, Dalucao, Muluozhai, Bayan Obo Mg-carbonatite and Ca-carbonatite has been confirmed. Based on previous research, we believe that liquid immiscibility not only facilitates pre-enrichment of rare earth elements but also contributes to subsequent REE mi","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106337"},"PeriodicalIF":3.2,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.oregeorev.2024.106341
Haidong Zhang , Bo Zhao , Jianchao Liu , Zilong Hu , Yeming Wang , Jialiang Zhao , Gengxin Deng , Longfei Gou , Fang Huang
The orogenic and intrusion-related gold deposits represent the two most significant types of gold reserves globally, collectively accounting for over half of the total and are formed associated with metamorphic and magmatic hydrous fluids, respectively. Theoretically, gold deposits should be a result of activities of the metamorphic and magmatic hydrous fluids that sourced, carried, and reserved gold. However, distinguishing differences between the metamorphic and magmatic fluids proves challenging mainly due to overlapping of trace elements, S, and Re-Os isotopes of sulfides and C, H, O, He, and Ar isotopes of the ore-forming fluids. Barium, as a fluid sensitive cation, is believed to faithfully record the sources and evolution of fluids. In this work, we presented the Ba isotopes of various ore-rocks from the Hadamen and Haoyaoerhudong gold deposits along the northern margin of the North China Craton. These two deposits have been well-defined the ore-forming fluids that originated from crystal-melt separation in alkaline granitic magma and dehydration of chlorite and mica from the black sales during metamorphism, respectively. The Ba isotopes exhibit significantly fractionation among the various ore-rocks from above two gold deposits. With increasing SiO2 content, δ138/134Ba values increased from −0.28 ‰ in the potassium silicate alteration zone, crossed −0.21 ‰ ∼ −0.19 ‰ in the potassium silicate alteration zone filled with sulfide-quartz veins, to −0.13 ‰ ∼ +0.01 ‰ in the sulfide-quartz veins. This suggests that the heavier Ba isotopes were preferentially incorporated into the evolving magmatic fluids primarily due to the crystallization of K-feldspar and barite. In contrast, δ138/134Ba values decreased from the carbonaceous slate (+0.73 ‰ ∼ +0.95 %) to sulfide veins (−0.28 ‰ ∼ +0.07 ‰), then increased to sulfide-quartz veins (+0.01 ‰). This phenomenon results from the continuously enhanced dissolution of diagenetic barite accompanying metamorphism and the crystallization of barite during evolution of metamorphic fluids. The microstructural characteristics also support that crystallization and dissolution of barite control significant Ba isotope fractionation in two types of fluids with different features. Furthermore, the magmatic and metamorphic fluids exhibit relative positive and negative relationships between Ba content and δ138/134Ba values, respectively. These geochemical features are also useful in defining the origin of the ore-forming fluids. Therefore, we propose that Ba isotope composition will be a new tool for deciphering the evolution of the Au-bearing ore-forming fluids and distinguishing the origin of the ore-forming fluids.
{"title":"Using barium isotopes to distinguish metamorphic and magmatic fluids for the gold deposits","authors":"Haidong Zhang , Bo Zhao , Jianchao Liu , Zilong Hu , Yeming Wang , Jialiang Zhao , Gengxin Deng , Longfei Gou , Fang Huang","doi":"10.1016/j.oregeorev.2024.106341","DOIUrl":"10.1016/j.oregeorev.2024.106341","url":null,"abstract":"<div><div>The orogenic and intrusion-related gold deposits represent the two most significant types of gold reserves globally, collectively accounting for over half of the total and are formed associated with metamorphic and magmatic hydrous fluids, respectively. Theoretically, gold deposits should be a result of activities of the metamorphic and magmatic hydrous fluids that sourced, carried, and reserved gold. However, distinguishing differences between the metamorphic and magmatic fluids proves challenging mainly due to overlapping of trace elements, S, and Re-Os isotopes of sulfides and C, H, O, He, and Ar isotopes of the ore-forming fluids. Barium, as a fluid sensitive cation, is believed to faithfully record the sources and evolution of fluids. In this work, we presented the Ba isotopes of various ore-rocks from the Hadamen and Haoyaoerhudong gold deposits along the northern margin of the North China Craton. These two deposits have been well-defined the ore-forming fluids that originated from crystal-melt separation in alkaline granitic magma and dehydration of chlorite and mica from the black sales during metamorphism, respectively. The Ba isotopes exhibit significantly fractionation among the various ore-rocks from above two gold deposits. With increasing SiO<sub>2</sub> content, <em>δ</em><sup>138/134</sup>Ba values increased from −0.28 ‰ in the potassium silicate alteration zone, crossed −0.21 ‰ ∼ −0.19 ‰ in the potassium silicate alteration zone filled with sulfide-quartz veins, to −0.13 ‰ ∼ +0.01 ‰ in the sulfide-quartz veins. This suggests that the heavier Ba isotopes were preferentially incorporated into the evolving magmatic fluids primarily due to the crystallization of K-feldspar and barite. In contrast, <em>δ</em><sup>138/134</sup>Ba values decreased from the carbonaceous slate (+0.73 ‰ ∼ +0.95 %) to sulfide veins (−0.28 ‰ ∼ +0.07 ‰), then increased to sulfide-quartz veins (+0.01 ‰). This phenomenon results from the continuously enhanced dissolution of diagenetic barite accompanying metamorphism and the crystallization of barite during evolution of metamorphic fluids. The microstructural characteristics also support that crystallization and dissolution of barite control significant Ba isotope fractionation in two types of fluids with different features. Furthermore, the magmatic and metamorphic fluids exhibit relative positive and negative relationships between Ba content and <em>δ</em><sup>138/134</sup>Ba values, respectively. These geochemical features are also useful in defining the origin of the ore-forming fluids. Therefore, we propose that Ba isotope composition will be a new tool for deciphering the evolution of the Au-bearing ore-forming fluids and distinguishing the origin of the ore-forming fluids.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106341"},"PeriodicalIF":3.2,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Paleozoic iron oxide copper–gold (IOCG) deposits in Xinjiang correspond to magmatic arc formations (Andean type) within the Central Asian Orogenic Belt (CAOB). These deposits include the Heijianshan, Duotoushan, Shuanglong, and Shaquanzi deposits in the Aqishan-Yamansu belt of Eastern Tianshan, which formed during the inversion of a continental arc-related basin (ca. 310–300 Ma). In contrast, the Laoshankou and Qiaoxiahala deposits along the northern margin of Eastern Junggar formed in an island arc setting (380–370 Ma). Detailed paragenetic studies of these deposits reveal a wide variety of alteration and mineralization patterns, including distinct but typical styles of magnetite and copper–gold mineralization. Fluid inclusion data and isotope tracing of ore-forming fluids indicate the involvement of magmatic-hydrothermal fluids is responsible for the early magnetite mineralization. However, for the late copper–gold mineralization, the deposits formed during the basin inversion have a significant involvement of non-magmatic fluids compared to those of island arc-related deposits. These non-magmatic fluids include basinal brines or residual seawater that reacted with andesitic host rocks. Comparing the IOCG-related magmatic rocks, the regional Bailingshan intrusive complex in the Eastern Tianshan formed during the basin inversion is from more reduced and water-poor parental magma compared to arc magma in the Eastern Junggar. However, the tectonic setting (basin inversion) facilitated the migration and involvement of external fluids, including sulfur, in the mineralization process, potentially compensating for the deficiencies of the magma to generate late economic copper–gold mineralization.
{"title":"Tectonic setting, mineralization, and ore geochemistry of the Paleozoic IOCG deposits in Xinjiang, NW China","authors":"Shuanliang Zhang , Liandang Zhao , Pei Liang , Hongjun Jiang , Weifeng Zhang","doi":"10.1016/j.oregeorev.2024.106317","DOIUrl":"10.1016/j.oregeorev.2024.106317","url":null,"abstract":"<div><div>The Paleozoic iron oxide copper–gold (IOCG) deposits in Xinjiang correspond to magmatic arc formations (Andean type) within the Central Asian Orogenic Belt (CAOB). These deposits include the Heijianshan, Duotoushan, Shuanglong, and Shaquanzi deposits in the Aqishan-Yamansu belt of Eastern Tianshan, which formed during the inversion of a continental arc-related basin (ca. 310–300 Ma). In contrast, the Laoshankou and Qiaoxiahala deposits along the northern margin of Eastern Junggar formed in an island arc setting (380–370 Ma). Detailed paragenetic studies of these deposits reveal a wide variety of alteration and mineralization patterns, including distinct but typical styles of magnetite and copper–gold mineralization. Fluid inclusion data and isotope tracing of ore-forming fluids indicate the involvement of magmatic-hydrothermal fluids is responsible for the early magnetite mineralization. However, for the late copper–gold mineralization, the deposits formed during the basin inversion have a significant involvement of non-magmatic fluids compared to those of island arc-related deposits. These non-magmatic fluids include basinal brines or residual seawater that reacted with andesitic host rocks. Comparing the IOCG-related magmatic rocks, the regional Bailingshan intrusive complex in the Eastern Tianshan formed during the basin inversion is from more reduced and water-poor parental magma compared to arc magma in the Eastern Junggar. However, the tectonic setting (basin inversion) facilitated the migration and involvement of external fluids, including sulfur, in the mineralization process, potentially compensating for the deficiencies of the magma to generate late economic copper–gold mineralization.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106317"},"PeriodicalIF":3.2,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-09DOI: 10.1016/j.oregeorev.2024.106336
Abulimiti Aibai , Xiaohua Deng , M. Santosh , Nuo Li , Xi Chen , Yongxiang Wang , Yanjing Chen , Wenjiao Xiao
Unlike the gold deposits typically hosted in metamorphosed volcanic-sedimentary sequences, the recently discovered Axile gold deposit (over 13 t Au at 5.35 g/t) is a unique example in the Chinese Altai for evaluating the genesis of intrusion-hosted lode gold deposits in metamorphic terranes. The orebodies in this deposit occur as quartz veins and altered tectonites hosted in the sinistrally sheared quartz diorite and biotite granite zones in the Habahe intrusion. The quartz vein-type ores are composed of quartz-pyrite veins and quartz-polymetallic sulfide veins, in which gold-tellurides also occur. The altered tectonites, spatially associated with the quartz veins, are composed of deformed and altered rocks of quartz diorite and biotite granite. Main alterations include quartz, sericite, calcite, chlorite, albite, pyrite, chalcopyrite, and gold-tellurides. Two types of fluid inclusions are identified in the ores, i.e., (1) carbonic-aqueous (C-type) and (2) aqueous (W-type), with the C-type being dominated. These fluid inclusions yield salinity ranging from 3.6 to 9.0 wt% NaCl equivalent and homogenization temperatures in the range of 249 − 387 ℃, suggesting a typical mesothermal NaCl-CO2-H2O system. The Axile deposit thus corresponds to an orogenic-type gold deposit.
The hydrothermal titanites in the auriferous quartz-pyrite veins yield in situ U-Pb ages around 278.4 ± 2.4 Ma (MSWD = 3.1, 2σ), which constrain the gold mineralization timing as Permian. The mineralized quartz diorite and biotite granite yield zircon U-Pb ages of 377.0 ± 1.0 Ma (MSWD = 0.1; 1σ) and 394.0 ± 1.2 Ma (MSWD = 0.4; 1σ), respectively, which show that the ore-hosting intrusions were emplaced in the Devonian, obviously earlier than the gold mineralization. The light δ13CV-PDB values (−15.5 ‰ to −6.7 ‰, average −10.7 ‰) of the CO2 extracted from the fluid inclusions display a significant contribution from the organic carbon in sediments. Given the sedimentary rocks underwent Permian greenschist to amphibolite facies metamorphism in the Chinese Altai, accompanied by the synchronous structural deformation and shearing activities, it could be concluded that the Axile gold deposit is formed by a shear zone-controlled mesothermal system that originated from metamorphic-devolatilization. The Chinese Altai Orogen is an orogenic-type gold metallogenic belt, containing both the intrusion- and metamorphic rock-hosted gold deposits, illustrated by a consistent genetic model.
{"title":"Formation of the intrusion-hosted orogenic-type gold lodes: Exemplified by the Axile gold deposit in the Chinese Altai","authors":"Abulimiti Aibai , Xiaohua Deng , M. Santosh , Nuo Li , Xi Chen , Yongxiang Wang , Yanjing Chen , Wenjiao Xiao","doi":"10.1016/j.oregeorev.2024.106336","DOIUrl":"10.1016/j.oregeorev.2024.106336","url":null,"abstract":"<div><div>Unlike the gold deposits typically hosted in metamorphosed volcanic-sedimentary sequences, the recently discovered Axile gold deposit (over 13 t Au at 5.35 g/t) is a unique example in the Chinese Altai for evaluating the genesis of intrusion-hosted lode gold deposits in metamorphic terranes. The orebodies in this deposit occur as quartz veins and altered tectonites hosted in the sinistrally sheared quartz diorite and biotite granite zones in the Habahe intrusion. The quartz vein-type ores are composed of quartz-pyrite veins and quartz-polymetallic sulfide veins, in which gold-tellurides also occur. The altered tectonites, spatially associated with the quartz veins, are composed of deformed and altered rocks of quartz diorite and biotite granite. Main alterations include quartz, sericite, calcite, chlorite, albite, pyrite, chalcopyrite, and gold-tellurides. Two types of fluid inclusions are identified in the ores, i.e., (1) carbonic-aqueous (C-type) and (2) aqueous (W-type), with the C-type being dominated. These fluid inclusions yield salinity ranging from 3.6 to 9.0 wt% NaCl equivalent and homogenization temperatures in the range of 249 − 387 ℃, suggesting a typical mesothermal NaCl-CO<sub>2</sub>-H<sub>2</sub>O system. The Axile deposit thus corresponds to an orogenic-type gold deposit.</div><div>The hydrothermal titanites in the auriferous quartz-pyrite veins yield <em>in situ</em> U-Pb ages around 278.4 ± 2.4 Ma (MSWD = 3.1, 2σ), which constrain the gold mineralization timing as Permian. The mineralized quartz diorite and biotite granite yield zircon U-Pb ages of 377.0 ± 1.0 Ma (MSWD = 0.1; 1σ) and 394.0 ± 1.2 Ma (MSWD = 0.4; 1σ), respectively, which show that the ore-hosting intrusions were emplaced in the Devonian, obviously earlier than the gold mineralization. The light δ<sup>13</sup>C<sub>V-PDB</sub> values (−15.5 ‰ to −6.7 ‰, average −10.7 ‰) of the CO<sub>2</sub> extracted from the fluid inclusions display a significant contribution from the organic carbon in sediments. Given the sedimentary rocks underwent Permian greenschist to amphibolite facies metamorphism in the Chinese Altai, accompanied by the synchronous structural deformation and shearing activities, it could be concluded that the Axile gold deposit is formed by a shear zone-controlled mesothermal system that originated from metamorphic-devolatilization. The Chinese Altai Orogen is an orogenic-type gold metallogenic belt, containing both the intrusion- and metamorphic rock-hosted gold deposits, illustrated by a consistent genetic model.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106336"},"PeriodicalIF":3.2,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.oregeorev.2024.106333
Xinfu Wang , Bo Li , Shucheng Tan , Zuopeng Xiang , Xiaoqing Liu , Fengze Liu
The Yangla is the largest and highest-grade antimony deposit (10 kt Sb @ 14.87 %) in the Jinshajiang suture zone, northwestern Yunnan (SW China). Pyrite and stibnite are the main sulfides, and calcite is the main gangue mineral in the antimony ores. Antimony mineralization can be divided into three stages: pre-ore stage pyrite and quartz, syn-ore stage (incl. early, main and late sub-stage) stibnite-pyrite-calcite-quartz, and supergene stage valentinite and limonite. The trace element compositions of the three pyrite and two stibnite generations have been analyzed by (LA-)ICP-MS here. The bulk ore-related calcite trace element compositions were also measured by ICP-MS. Trace element correlations and principal component analysis (PCA) show that the majority of trace elements occur as solid solution and micro-/nano-inclusions in pyrite and stibnite. In pyrite, the Sb substitutes into the crystal lattice with Tl, Cu and Ag via (Tl++Cu++Ag+) + Sb3+ ↔ 2Fe2+. Gold occurs as invisible gold (Au+) and enters pyrite via the coupled substitution of As3+ + Au3+ + □ ↔ 3Fe2+ and/or As3+ + Au3+ + □ ↔ 3Cu2+. In stibnite, the Cu, Pb and As enter the crystal lattice via the coupled substitution of 2Sb3+ ↔ Cu+ + Pb2+ + As3+. Trace element features of calcite are highly similar to the Devonian Linong Formation (2nd member) marble, suggesting that the ore-forming fluid is closely associated with the marble. Syn-ore calcite is characterized by its higher Fe, Mn and MREE concentrations, and can be regarded as a geochemical fingerprint for metallogenic prediction. The δCe (0.67–0.83, avg. 0.75) and δEu (1.40–2.51, avg. 1.89) values suggest that the antimony precipitation occurred under reducing to weakly oxidizing conditions. The atomic Yb/Ca, Yb/La, Tb/Ca, and Tb/La ratios of the syn-ore calcite imply that the antimony mineralization can be attributed to hydrothermal genesis. This deduction is also supported by that data of pyrite Ⅰ, Ⅱ, and Ⅲ mainly plotted inside the hydrothermal fields in the Co/Ni, As/Ag, Sb/Bi and Co-Ni-As discrimination plots. The Yangla stibnite ore samples mimic stibnite from typical hydrothermal mineralization systems (e.g., Woxi Au-Sb-W deposit, South China) in the Cu vs. Pb plot, which further supports a hydrothermal origin of the antimony. Therefore, we propose that the hydrothermal Sb mineralization is closely related to the Devonian carbonate rocks at Yangla.
{"title":"Geology and antimony mineralization of the Yangla polymetallic orefield in northwestern Yunnan, SW China: Trace element geochemistry of sulfides and calcite","authors":"Xinfu Wang , Bo Li , Shucheng Tan , Zuopeng Xiang , Xiaoqing Liu , Fengze Liu","doi":"10.1016/j.oregeorev.2024.106333","DOIUrl":"10.1016/j.oregeorev.2024.106333","url":null,"abstract":"<div><div>The Yangla is the largest and highest-grade antimony deposit (10 kt Sb @ 14.87 %) in the Jinshajiang suture zone, northwestern Yunnan (SW China). Pyrite and stibnite are the main sulfides, and calcite is the main gangue mineral in the antimony ores. Antimony mineralization can be divided into three stages: pre-ore stage pyrite and quartz, <em>syn</em>-ore stage (incl. early, main and late sub-stage) stibnite-pyrite-calcite-quartz, and supergene stage valentinite and limonite. The trace element compositions of the three pyrite and two stibnite generations have been analyzed by (LA-)ICP-MS here. The bulk ore-related calcite trace element compositions were also measured by ICP-MS. Trace element correlations and principal component analysis (PCA) show that the majority of trace elements occur as solid solution and micro-/nano-inclusions in pyrite and stibnite. In pyrite, the Sb substitutes into the crystal lattice with Tl, Cu and Ag via (Tl<sup>+</sup>+Cu<sup>+</sup>+Ag<sup>+</sup>) + Sb<sup>3+</sup> ↔ 2Fe<sup>2+</sup>. Gold occurs as invisible gold (Au<sup>+</sup>) and enters pyrite via the coupled substitution of As<sup>3+</sup> + Au<sup>3+</sup> + □ ↔ 3Fe<sup>2+</sup> and/or As<sup>3+</sup> + Au<sup>3+</sup> + □ ↔ 3Cu<sup>2+</sup>. In stibnite, the Cu, Pb and As enter the crystal lattice via the coupled substitution of 2Sb<sup>3+</sup> ↔ Cu<sup>+</sup> + Pb<sup>2+</sup> + As<sup>3+</sup>. Trace element features of calcite are highly similar to the Devonian Linong Formation (2nd member) marble, suggesting that the ore-forming fluid is closely associated with the marble. Syn-ore calcite is characterized by its higher Fe, Mn and MREE concentrations, and can be regarded as a geochemical fingerprint for metallogenic prediction. The δCe (0.67–0.83, avg. 0.75) and δEu (1.40–2.51, avg. 1.89) values suggest that the antimony precipitation occurred under reducing to weakly oxidizing conditions. The atomic Yb/Ca, Yb/La, Tb/Ca, and Tb/La ratios of the <em>syn</em>-ore calcite imply that the antimony mineralization can be attributed to hydrothermal genesis. This deduction is also supported by that data of pyrite Ⅰ, Ⅱ, and Ⅲ mainly plotted inside the hydrothermal fields in the Co/Ni, As/Ag, Sb/Bi and Co-Ni-As discrimination plots. The Yangla stibnite ore samples mimic stibnite from typical hydrothermal mineralization systems (e.g., Woxi Au-Sb-W deposit, South China) in the Cu vs. Pb plot, which further supports a hydrothermal origin of the antimony. Therefore, we propose that the hydrothermal Sb mineralization is closely related to the Devonian carbonate rocks at Yangla.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"175 ","pages":"Article 106333"},"PeriodicalIF":3.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.oregeorev.2024.106318
Xinhao Li , Guiqing Xie , Wei Jian , Jingwen Mao
In recent years, an increasing number of studies have reported the enrichment of Te, Se, and Co in magmatic-hydrothermal deposits in the Mid-Lower Yangtze River metallogenic belt (MLYRB), especially in Au-rich deposits. The Jiguanzui deposit, a representative porphyry-skarn Au-Cu deposit in the MLYRB, Eastern China, is characterized by significant critical metal (Te, Se, Co) association. Based on previous studies on critical metals distribution, this study presents trace element geochemistry of various sulfide minerals (chalcopyrite, bornite, sphalerite, molybdenite) through LA-ICP-MS analysis, aiming to reveal the distribution and modes of occurrences of Te, Se, Co, and Au among sulfide minerals in the Jiguanzui Au-Cu deposit. Analytical results indicate that, except for molybdenite, which hosts high concentrations of both Te and Se, pyrite and chalcopyrite generally have higher Te contents than bornite and sphalerite, whereas bornite and chalcopyrite exhibit relatively high Se concentrations. Cobalt and Au are dominantly hosted in pyrite and chalcopyrite, respectively, although the highest Au concentration up to 14 ppm was tested in pyrite. Principal component analysis of trace element contents, time-resolved LA-ICP-MS signal depth profiles, and trace element correlations suggest that Te is generally incorporated as silver and bismuth telluride mineral inclusions in the sulfides, whereas Se and Co are incorporated into the lattice of sulfide minerals. The intimate Pb-Bi-(Cu)-Au associations suggest that tiny mineral inclusions of native Au coexisting with either Cu-Bi sulfosalts or Pb sulfides or sulfosalts. Comparative analysis of the distribution patterns of Te, Se, Co, and Au in porphyry-skarn deposits within the MLYRB suggest that pyrite is the main Te-hosting sulfide mineral, whereas chalcopyrite is the major host for Se, which means Te hosted in pyrite is difficult to recover under current technologies. Pyrite and sphalerite are the major hosts of Co, and chalcopyrite is the main Au-bearing sulfide mineral in the deposits.
近年来，越来越多的研究报道了长江中下游成矿带（MLYRB）岩浆-热液矿床中Te、Se和Co的富集，尤其是在富金矿床中。鸡冠嘴矿床是中国东部长江中下游成矿带具有代表性的斑岩-矽卡岩型金-铜矿床，其特征是临界金属（Te、Se、Co）关联显著。在前人对临界金属分布研究的基础上，本研究通过LA-ICP-MS分析，对各种硫化物矿物（黄铜矿、辉铜矿、闪锌矿、辉钼矿）进行了微量元素地球化学分析，旨在揭示鸡冠嘴金铜矿中Te、Se、Co、Au在硫化物矿物中的分布和出现模式。分析结果表明，除辉钼矿同时富含高浓度的 Te 和 Se 外，黄铁矿和黄铜矿的 Te 含量普遍高于辉铜矿和闪锌矿，而辉铜矿和黄铜矿的 Se 含量相对较高。钴和金分别主要赋存于黄铁矿和黄铜矿中，但黄铁矿中的金含量最高，达到 14 ppm。痕量元素含量的主成分分析、时间分辨 LA-ICP-MS 信号深度剖面和痕量元素相关性表明，碲一般以银和铋碲化物矿物包裹体的形式被包裹在硫化物中，而硒和钴则被包裹在硫化物矿物的晶格中。铅-铋-（铜）-金的密切关联表明，原生金的微小矿物包裹体与铜-铋硫化物或铅硫化物或硫化物共存。对MLYRB地区斑岩-矽卡岩矿床中的铁、硒、钴和金分布模式的比较分析表明，黄铁矿是主要的碲寄生硫化矿物，而黄铜矿是硒的主要寄生矿物，这意味着黄铁矿中的碲在现有技术条件下难以回收。黄铁矿和闪锌矿是钴的主要矿床，黄铜矿是矿床中主要的含金硫化矿物。
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