Pub Date : 2025-02-15DOI: 10.1016/j.oregeorev.2025.106499
Zhaohua Chen , Yongjun Shao , Qingquan Liu , Xiong Zhang , Yuce Zhang , Hongtao Zhao , Jie Chen , Lijun Hu
The newly discovered Jinming gold deposit in northeastern Hunan province (Eastern China) is tectonically located in the Jiangnan Orogen. The fault-controlled auriferous quartz ore veins are primarily developed in the low-grade metamorphosed Neoproterozoic Lengjiaxi Group. The alteration/mineralization comprises stage I quartz-pyrite mineralization, stage II quartz-native gold-polymetallic sulfide mineralization, and stage Ⅲ quartz-carbonate veining. Our in situ sericite Rb-Sr dating on stage II ore yielded an Early Devonian age of 412.4 ± 8.4 Ma (MSWD = 1.1). Five types of pyrite were identified, i.e., Py1 (Py1a and Py1b) in stage Ⅰ, and Py2 (Py2a, Py2b, and Py2c) in stage Ⅱ. Py1 has relatively low trace element contents and narrow δ34S range (Py1a: −5.53 to −4.82 ‰, Py1b: −5.29 to −4.72 ‰), whereas Py2 is Au-As-Co-Ni rich with a broader δ34S range (Py2a: −6.00 to −4.94 ‰, Py2b: −13.80 to −7.99 ‰, Py2c: –23.45 to −18.70 ‰). The distinct trace element and sulfur isotope features in Py1 and Py2 imply major physicochemical changes in the ore-forming fluids from stage I to II. At Jinming, gold occurs as native gold and refractory gold (Au+) in pyrite and arsenopyrite from stage II, and the invisible gold is primarily found as solid solution gold (Au+) within the lattice structure of pyrite. A marked positive correlation between the concentrations of Au and arsenic (As) in pyrite suggests a strong relationship between Au enrichment and As content. The pyrite’s element and sulfur isotope features imply a deep metamorphosed strata source for the ore material at Jinming. Geological and geochemical evidence suggests that the Jinming gold deposit is best classified as an orogenic type, associated with the Caledonian intracontinental orogeny.
{"title":"Metallogeny of the Jinming gold deposit in northeast Hunan, Jiangnan Orogen: Constraints from in situ sericite Rb-Sr dating, pyrite trace elements and S isotope geochemistry","authors":"Zhaohua Chen , Yongjun Shao , Qingquan Liu , Xiong Zhang , Yuce Zhang , Hongtao Zhao , Jie Chen , Lijun Hu","doi":"10.1016/j.oregeorev.2025.106499","DOIUrl":"10.1016/j.oregeorev.2025.106499","url":null,"abstract":"<div><div>The newly discovered Jinming gold deposit in northeastern Hunan province (Eastern China) is tectonically located in the Jiangnan Orogen. The fault-controlled auriferous quartz ore veins are primarily developed in the low-grade metamorphosed Neoproterozoic Lengjiaxi Group. The alteration/mineralization comprises stage I quartz-pyrite mineralization, stage II quartz-native gold-polymetallic sulfide mineralization, and stage Ⅲ quartz-carbonate veining. Our in situ sericite Rb-Sr dating on stage II ore yielded an Early Devonian age of 412.4 ± 8.4 Ma (MSWD = 1.1). Five types of pyrite were identified, i.e., Py1 (Py1a and Py1b) in stage Ⅰ, and Py2 (Py2a, Py2b, and Py2c) in stage Ⅱ. Py1 has relatively low trace element contents and narrow δ<sup>34</sup>S range (Py1a: −5.53 to −4.82 ‰, Py1b: −5.29 to −4.72 ‰), whereas Py2 is Au-As-Co-Ni rich with a broader δ<sup>34</sup>S range (Py2a: −6.00 to −4.94 ‰, Py2b: −13.80 to −7.99 ‰, Py2c: –23.45 to −18.70 ‰). The distinct trace element and sulfur isotope features in Py1 and Py2 imply major physicochemical changes in the ore-forming fluids from stage I to II. At Jinming, gold occurs as native gold and refractory gold (Au<sup>+</sup>) in pyrite and arsenopyrite from stage II, and the invisible gold is primarily found as solid solution gold (Au<sup>+</sup>) within the lattice structure of pyrite. A marked positive correlation between the concentrations of Au and arsenic (As) in pyrite suggests a strong relationship between Au enrichment and As content. The pyrite’s element and sulfur isotope features imply a deep metamorphosed strata source for the ore material at Jinming. Geological and geochemical evidence suggests that the Jinming gold deposit is best classified as an orogenic type, associated with the Caledonian intracontinental orogeny.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106499"},"PeriodicalIF":3.2,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445349","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 : 2025-02-13DOI: 10.1016/j.oregeorev.2025.106498
Ahmad Reza Mokhtari, Pouran Behnia, Bruno Lafrance, Mostafa Naghizadeh, Jack M. Simmons, Jeff R. Harris
Mineral Prospectivity Mapping has been applied to define exploration targets for orogenic gold mineralization in the world-class Malartic-Val-d’Or area (Quebec) of the Abitibi greenstone belt, a region that contributes significantly to Canada’s annual gold production. This research utilizes lithological, geophysical, and structural data from the Malartic transect, collected as part of the Metal Earth project, to investigate factors controlling gold distribution in the region. Stepwise logistic regression and random forest algorithms were employed to map mineral prospectivity for gold potential. The overall accuracy indicates that the random forest method has outperformed logistic regression, although the latter produced an acceptable model. This conclusion is supported by the classification accuracy validated using an independent Au occurrence database and the performance metrics generated by the random forest and logistic regression models. Crustal density, shear zones, and faults are strong predictors for distinguishing mineralized and non-mineralized locations, as identified by both Random Forest and Logistic Regression models. In the Malartic-Val-d’Or region, subvertical conductive anomalies revealed by magnetotelluric data align closely with major shear zones and crustal-scale structures, such as the Cadillac-Larder Lake deformation zone, which hosts significant gold deposits. These anomalies suggest a paleo-hydrothermal footprint of mineralizing fluids and highlight their critical role in the formation of orogenic gold deposits, a pattern also observed in other mining camps across the Superior craton. These results and associated mineral prospectivity maps are integral for greenfields exploration in the Malartic region and may offer valuable insights for mineral exploration in other greenstone belts of the Superior craton.
{"title":"Mineral prospectivity mapping of orogenic gold mineralization in the Malartic-Val-d’Or Transect area, Metal Earth project, Canada","authors":"Ahmad Reza Mokhtari, Pouran Behnia, Bruno Lafrance, Mostafa Naghizadeh, Jack M. Simmons, Jeff R. Harris","doi":"10.1016/j.oregeorev.2025.106498","DOIUrl":"10.1016/j.oregeorev.2025.106498","url":null,"abstract":"<div><div>Mineral Prospectivity Mapping has been applied to define exploration targets for orogenic gold mineralization in the world-class Malartic-Val-d’Or area (Quebec) of the Abitibi greenstone belt, a region that contributes significantly to Canada’s annual gold production. This research utilizes lithological, geophysical, and structural data from the Malartic transect, collected as part of the Metal Earth project, to investigate factors controlling gold distribution in the region. Stepwise logistic regression and random forest algorithms were employed to map mineral prospectivity for gold potential. The overall accuracy indicates that the random forest method has outperformed logistic regression, although the latter produced an acceptable model. This conclusion is supported by the classification accuracy validated using an independent Au occurrence database and the performance metrics generated by the random forest and logistic regression models. Crustal density, shear zones, and faults are strong predictors for distinguishing mineralized and non-mineralized locations, as identified by both Random Forest and Logistic Regression models. In the Malartic-Val-d’Or region, subvertical conductive anomalies revealed by magnetotelluric data align closely with major shear zones and crustal-scale structures, such as the Cadillac-Larder Lake deformation zone, which hosts significant gold deposits. These anomalies suggest a paleo-hydrothermal footprint of mineralizing fluids and highlight their critical role in the formation of orogenic gold deposits, a pattern also observed in other mining camps across the Superior craton. These results and associated mineral prospectivity maps are integral for greenfields exploration in the Malartic region and may offer valuable insights for mineral exploration in other greenstone belts of the Superior craton.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106498"},"PeriodicalIF":3.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428122","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 : 2025-02-12DOI: 10.1016/j.oregeorev.2025.106492
Alan Cardenas-Vera , David R. Lentz , Christopher R.M. McFarlane , Kathleen G. Thorne
The Cape Spencer gold deposit is situated proximal to the boundary between two major lithotectonic zones of the Canadian Appalachians, the Caledonia and Meguma terranes, within a fold-thrust belt in southern New Brunswick along the Minas Fault Zone. Gold mineralization occurs in quartz-dominant veins with 2–5 % sulphides hosted by the highly deformed and sheared rocks of the Millican Lake Granite and the Cape Spencer Formation. In this research, in situ S isotope and trace-element concentrations of pyrite in combination with bulk pyrite Pb isotope analyses are presented to better understand the metal sources, fluid channels, and mechanisms of ore deposition. Based on textural characteristics and trace element concentrations, five generations of pyrite from the hydrothermal stage were identified in the ore bodies: Py1a, Py1b, Py2a, Py2b, and Py3. The first pyrite generations, Py1a and Py1b (substage I), contain higher concentrations of Co and Ni than pyrite from substages II and III and have positive δ34S values ranging from +6.8 to +18.7 ‰. Economic concentrations of gold are associated with Py2a and Py2b (substage II), which occur as spongy and porous pyrite; Py2a pyrites contain visible gold along fractures and margins. Py1a to Py2b display an Au-Ag-Pb-Bi-Te association, also supported by the presence of hessite, petzite, sylvanite, and native bismuth in the gold ores. Pyrites from substage II display slightly less positive values of δ34S of +1.0 to +12.3 ‰. The last identified pyrite generation, Py3 (substage III), contains no gold and is characterized by high concentrations of As and Cu compared with pyrites from the previous generations and negative δ34S values of −9.8 to −3.8 ‰. This sequential shift towards more negative values from Py1 to Py2 may be induced by phase separation and wall-rock sulphidation processes, in addition to interaction with rocks of the Lancaster Formation for Py3. The generally low gold contents (<0.3 ppm) in pyrite and visible gold within fractures and along pyrite grain margins suggest post-depositional dissolution of pyrite. The influx of ore fluids, consistent with cyclic decompression, induced the removal of iron from Fe-bearing minerals, mainly specular hematite that led to an increase of the Fe in the fluid, destabilizing the complexes and promoted the depletion of S and subsequent gold precipitation. The ore-forming fluids were transported along major structures and derived from a mixed source that includes intrusive and metasedimentary rocks from the Avalonia and Meguma terranes, sharing similar characteristics to those values from the Meguma gold deposits, as indicated by both the S and Pb isotope signatures.
{"title":"Assessment of pyrite and arsenopyrite compositions, in situ S isotopes, and bulk Pb isotopes from the Cape Spencer gold deposit, New Brunswick, Canada","authors":"Alan Cardenas-Vera , David R. Lentz , Christopher R.M. McFarlane , Kathleen G. Thorne","doi":"10.1016/j.oregeorev.2025.106492","DOIUrl":"10.1016/j.oregeorev.2025.106492","url":null,"abstract":"<div><div>The Cape Spencer gold deposit is situated proximal to the boundary between two major lithotectonic zones of the Canadian Appalachians, the Caledonia and Meguma terranes, within a fold-thrust belt in southern New Brunswick along the Minas Fault Zone. Gold mineralization occurs in quartz-dominant veins with 2–5 % sulphides hosted by the highly deformed and sheared rocks of the Millican Lake Granite and the Cape Spencer Formation. In this research, <em>in situ</em> S isotope and trace-element concentrations of pyrite in combination with bulk pyrite Pb isotope analyses are presented to better understand the metal sources, fluid channels, and mechanisms of ore deposition. Based on textural characteristics and trace element concentrations, five generations of pyrite from the hydrothermal stage were identified in the ore bodies: Py1a, Py1b, Py2a, Py2b, and Py3. The first pyrite generations, Py1a and Py1b (substage I), contain higher concentrations of Co and Ni than pyrite from substages II and III and have positive δ<sup>34</sup>S values ranging from +6.8 to +18.7 ‰. Economic concentrations of gold are associated with Py2a and Py2b (substage II), which occur as spongy and porous pyrite; Py2a pyrites contain visible gold along fractures and margins. Py1a to Py2b display an Au-Ag-Pb-Bi-Te association, also supported by the presence of hessite, petzite, sylvanite, and native bismuth in the gold ores. Pyrites from substage II display slightly less positive values of δ<sup>34</sup>S of +1.0 to +12.3 ‰. The last identified pyrite generation, Py3 (substage III), contains no gold and is characterized by high concentrations of As and Cu compared with pyrites from the previous generations and negative δ<sup>34</sup>S values of −9.8 to −3.8 ‰. This sequential shift towards more negative values from Py1 to Py2 may be induced by phase separation and wall-rock sulphidation processes, in addition to interaction with rocks of the Lancaster Formation for Py3. The generally low gold contents (<0.3 ppm) in pyrite and visible gold within fractures and along pyrite grain margins suggest post-depositional dissolution of pyrite. The influx of ore fluids, consistent with cyclic decompression, induced the removal of iron from Fe-bearing minerals, mainly specular hematite that led to an increase of the Fe in the fluid, destabilizing the <span><math><msubsup><mrow><mi>A</mi><mi>u</mi><mo>(</mo><mi>H</mi><mi>S</mi><mo>)</mo></mrow><mrow><mn>2</mn></mrow><mo>-</mo></msubsup></math></span> complexes and promoted the depletion of S and subsequent gold precipitation. The ore-forming fluids were transported along major structures and derived from a mixed source that includes intrusive and metasedimentary rocks from the Avalonia and Meguma terranes, sharing similar characteristics to those values from the Meguma gold deposits, as indicated by both the S and Pb isotope signatures.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106492"},"PeriodicalIF":3.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422208","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 : 2025-02-11DOI: 10.1016/j.oregeorev.2025.106497
Rou Peng , Ruidong Yang , Jiyan Chen , Junbo Gao , Lei Gao , Chuanqian Gao
The Early Cambrian represents a globally significant phosphorus-formation period, particularly noted for producing REY-rich phosphorites in South China. However, substantial differences exist in the REY enrichment levels among these phosphorites. Particularly, the REY contents of the Early Cambrian Meishucun Stage phosphorites from Guizhou and Yunnan exhibit pronounced disparities, with the controlling factors behind these variations remaining a subject of debate. To address this issue, this study conducted comparative analyses of representative REY-bearing phosphorites from Cambrian Meishucun Stage in Bailongtan, Yunnan province, and Zhijin, Guizhou province, China. Advanced analytic techniques, including XRF, ICP-MS, and ICP-OES, were employed to determine major, trace elements and REY concentrations in different phosphorite types. And complementary methodologies including OM, SM, SEM-EDS, and EPMA were utilized to examine the mineralogical and textural features. The results indicated that biofossils preserved in the phosphorites of both regions are small shelly fossils (SSFs), with carbonate fluorapatite as the principal component. Zhijin phosphorites exhibit significantly higher REY enrichment compared with Bailongtan phosphorites, and REY contents positively correlate with the abundance of SSFs. In-situ analyses revealed that REYs are primarily concentrated within SSFs, which were better preserved in oxic and open environments with relatively slow sedimentation rates. The multilayered nested structures of SSFs facilitate the absorption of REYs from seawater and porewater, which corresponding to the biogenic structures of bioapatite observed in modern deep-sea REY-rich sediments. These findings suggested that SSFs play a crucial role in REY enrichment, with Zhijinites potentially serving as the optimal host phase for REY enrichment. Conclusively, biota play an important part in the REY-rich mineralization of phosphorites, offering new insights into the genesis of global sedimentary REY-bearing phosphorites. This understanding also opens new considerations for optimizing REY extraction processes from such phosphorites.
{"title":"Biogenic mineralization controls exceptional REY enrichment in Early Cambrian phosphorites from South China","authors":"Rou Peng , Ruidong Yang , Jiyan Chen , Junbo Gao , Lei Gao , Chuanqian Gao","doi":"10.1016/j.oregeorev.2025.106497","DOIUrl":"10.1016/j.oregeorev.2025.106497","url":null,"abstract":"<div><div>The Early Cambrian represents a globally significant phosphorus-formation period, particularly noted for producing REY-rich phosphorites in South China. However, substantial differences exist in the REY enrichment levels among these phosphorites. Particularly, the REY contents of the Early Cambrian Meishucun Stage phosphorites from Guizhou and Yunnan exhibit pronounced disparities, with the controlling factors behind these variations remaining a subject of debate. To address this issue, this study conducted comparative analyses of representative REY-bearing phosphorites from Cambrian Meishucun Stage in Bailongtan, Yunnan province, and Zhijin, Guizhou province, China. Advanced analytic techniques, including XRF, ICP-MS, and ICP-OES, were employed to determine major, trace elements and REY concentrations in different phosphorite types. And complementary methodologies including OM, SM, SEM-EDS, and EPMA were utilized to examine the mineralogical and textural features. The results indicated that biofossils preserved in the phosphorites of both regions are small shelly fossils (SSFs), with carbonate fluorapatite as the principal component. Zhijin phosphorites exhibit significantly higher REY enrichment compared with Bailongtan phosphorites, and REY contents positively correlate with the abundance of SSFs. In-situ analyses revealed that REYs are primarily concentrated within SSFs, which were better preserved in oxic and open environments with relatively slow sedimentation rates. The multilayered nested structures of SSFs facilitate the absorption of REYs from seawater and porewater, which corresponding to the biogenic structures of bioapatite observed in modern deep-sea REY-rich sediments. These findings suggested that SSFs play a crucial role in REY enrichment, with <em>Zhijinites</em> potentially serving as the optimal host phase for REY enrichment. Conclusively, biota play an important part in the REY-rich mineralization of phosphorites, offering new insights into the genesis of global sedimentary REY-bearing phosphorites. This understanding also opens new considerations for optimizing REY extraction processes from such phosphorites.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106497"},"PeriodicalIF":3.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422210","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 : 2025-02-10DOI: 10.1016/j.oregeorev.2025.106491
Zhong-Cheng Zeng , Jing-Jing Fan , Zi-Long Wang , Biao Du , Peng Wang , Zeng-Lin Hong
Pegmatite-host Li deposits provide substantial Li resource in the globe. However, the mechanism of Li enrichment in granitic pegmatites remain enigmatic. Here, we report age and whole-rock geochemical data for the garnet-tourmaline-bearing granites (GTGs) and tourmaline-bearing granites (TGs) from the Dahongliutan rare-metal pegmatite ore field located in the Western Kunlun orogen, NW China. The formation of Li-rich pegmatites in this ore field was proposed to have an intimate temporal-spatial association to the two-mica granites (TMGs). Zircon U–Pb dating for the GTGs and TGs yielded ages of 203.2 ± 2.3 and 203.4 ± 2.7 Ma, respectively. These ages are slightly younger than those of the TMGs (ca. 220–208 Ma), but overlapping with or older than those of the Li-rich pegmatites (ca. 214–190 Ma) reported in this area. The GTGs and TGs have middle to upper crust-like Sr–Nd isotope compositions ((87Sr/86Sr)i = 0.7159–0.7227; εNd(t) = − 10.7 to − 9.67), similar to those of the TMGs and Li-rich pegmatites. The decreasing CaO, MgO, TFe2O3, Sr, Ba and rare earth element contents, and increasing Na2O, K2O contents and Na2O/K2O ratios from the TMGs to GTGs, and to TGs, suggests fractionation of biotite, plagioclase and K-feldspar, monazite, muscovite, and garnet from the TMG magma. These evidence together with the field observations indicate that these granites and pegmatites in the Dahongliutan ore field represent a cogenetic evolutionary sequence. However, the contents of the incompatible element of Li decrease sharply from the TMGs to GTGs and TGs, which is likely resulted from magmatic fluid exsolution. Geochemical modeling for Li show that fluid saturation occurred at the early stage of magma evolution. In the following, the exsoluted fluids accumulation accompany by extraction of large amounts of fluid-soluble elements such as Li and Cs from the residual melts, and their removal and migration away from the granite system, may be pivotal in the generation of the Li-rich pegmatites.
{"title":"The role of fluid exsolution in the Li enrichment in granitic pegmatites: A case study from the Dahongliutan Li ore field in West Kunlun","authors":"Zhong-Cheng Zeng , Jing-Jing Fan , Zi-Long Wang , Biao Du , Peng Wang , Zeng-Lin Hong","doi":"10.1016/j.oregeorev.2025.106491","DOIUrl":"10.1016/j.oregeorev.2025.106491","url":null,"abstract":"<div><div>Pegmatite-host Li deposits provide substantial Li resource in the globe. However, the mechanism of Li enrichment in granitic pegmatites remain enigmatic. Here, we report age and whole-rock geochemical data for the garnet-tourmaline-bearing granites (GTGs) and tourmaline-bearing granites (TGs) from the Dahongliutan rare-metal pegmatite ore field located in the Western Kunlun orogen, NW China. The formation of Li-rich pegmatites in this ore field was proposed to have an intimate temporal-spatial association to the two-mica granites (TMGs). Zircon U–Pb dating for the GTGs and TGs yielded ages of 203.2 ± 2.3 and 203.4 ± 2.7 Ma, respectively. These ages are slightly younger than those of the TMGs (ca. 220–208 Ma), but overlapping with or older than those of the Li-rich pegmatites (ca. 214–190 Ma) reported in this area. The GTGs and TGs have middle to upper crust-like Sr–Nd isotope compositions ((<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> = 0.7159–0.7227; ε<sub>Nd</sub>(<em>t</em>) = <strong>−</strong> 10.7 to <strong>−</strong> 9.67), similar to those of the TMGs and Li-rich pegmatites. The decreasing CaO, MgO, TFe<sub>2</sub>O<sub>3</sub>, Sr, Ba and rare earth element contents, and increasing Na<sub>2</sub>O, K<sub>2</sub>O contents and Na<sub>2</sub>O/K<sub>2</sub>O ratios from the TMGs to GTGs, and to TGs, suggests fractionation of biotite, plagioclase and K-feldspar, monazite, muscovite, and garnet from the TMG magma. These evidence together with the field observations indicate that these granites and pegmatites in the Dahongliutan ore field represent a cogenetic evolutionary sequence. However, the contents of the incompatible element of Li decrease sharply from the TMGs to GTGs and TGs, which is likely resulted from magmatic fluid exsolution. Geochemical modeling for Li show that fluid saturation occurred at the early stage of magma evolution. In the following, the exsoluted fluids accumulation accompany by extraction of large amounts of fluid-soluble elements such as Li and Cs from the residual melts, and their removal and migration away from the granite system, may be pivotal in the generation of the Li-rich pegmatites.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106491"},"PeriodicalIF":3.2,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422416","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 : 2025-02-10DOI: 10.1016/j.oregeorev.2025.106495
Ming-Sen Fan , Pei Ni , Jun-Yi Pan , Jun-Ying Ding , Zhe Chi , Jian-Ming Cui , Zhi-Lin Cheng , Fei-Peng Fan , Guang-Shi Zheng
The Dongji Au deposit represents the largest gold deposit in the Zhenghe region of South China with a proven reserve of 12.5 t gold and 136 t Silver. The deposit occurs mostly in Upper Jurassic rhyolite porphyry and partly in volcaniclastic rocks and is controlled by NE trending breccia zone. Our investigations suggest that two distinct stages of gold mineralization occur at Dongji: the stage 1 is dominated by quartz, pyrite, and arsenopyrite, with visible Au − Ag minerals, and occurs as a wide variety of structural styles that include individual veins, fracture stockworks and breccias; and the late stage 2 is characterized by gold-bearing pyrite, illite, chalcedony, and apatite, mainly distributed in cement of breccia style ores. The host rocks near orebodies develop pronounced illitization, silicification, weak chloritization. Microthermometric results from fluid inclusions within multi-generation growth zones of quartz in stage 1 and secondary fractures associated with later stage yielded homogenization temperatures (320 ∼ 411℃ and 218 ∼ 332 ℃, respectively) and salinities (0.4 ∼ 4.2 wt% NaCl equivalents and 0.7 ∼ 3.9 wt% NaCl equivalents, respectively). Combined with quartz titanium thermometer results, the high temperature and low salinity ranges of liquid-rich two-phase fluid inclusion in quartz of stage 1 indicate that the ore-forming fluid originated from magmatic vapor, which contracted into an aqueous liquid by cooling at elevated lithostatic pressure above the critical curve of the salt-water fluid system. The δDV-SMOW values of stage1 quartz range from − 69.9 ‰ to − 60.9 ‰, with δ18OH2O‰ values between − 0.9 ‰ and 1.4 ‰, implying the auriferous fluids derive from a magmatic with minor meteoric mixed source. The δ34SV–CDT values of pyrite of stage 1 and 2 range from –0.3 to 8.0 ‰, revealing that sulfur mainly originates from the magma. The microthermometric data and quartz composition evolution suggest a fluid mixing contribution to metal precipitation. Combined with the geology, gangue and ore mineral assemblage, alteration, fluid inclusion, and H–O–S isotopic characteristics, we propose that the auriferous ore-forming fluids of the Dongji deposit may be the product of magma vapor contraction and migration in a porphyry–epithermal transitional gold system. These findings also indicate a great prospecting potential for the porphyry type mineralization at depth.
{"title":"Records of high temperature ore fluids through magmatic vapor contraction from the Dongji gold deposit, SE China","authors":"Ming-Sen Fan , Pei Ni , Jun-Yi Pan , Jun-Ying Ding , Zhe Chi , Jian-Ming Cui , Zhi-Lin Cheng , Fei-Peng Fan , Guang-Shi Zheng","doi":"10.1016/j.oregeorev.2025.106495","DOIUrl":"10.1016/j.oregeorev.2025.106495","url":null,"abstract":"<div><div>The Dongji Au deposit represents the largest gold deposit in the Zhenghe region of South China with a proven reserve of 12.5 t gold and 136 t Silver. The deposit occurs mostly in Upper Jurassic rhyolite porphyry and partly in volcaniclastic rocks and is controlled by NE trending breccia zone. Our investigations suggest that two distinct stages of gold mineralization occur at Dongji: the stage 1 is dominated by quartz, pyrite, and arsenopyrite, with visible Au − Ag minerals, and occurs as a wide variety of structural styles that include individual veins, fracture stockworks and breccias; and the late stage 2 is characterized by gold-bearing pyrite, illite, chalcedony, and apatite, mainly distributed in cement of breccia style ores. The host rocks near orebodies develop pronounced illitization, silicification, weak chloritization. Microthermometric results from fluid inclusions within multi-generation growth zones of quartz in stage 1 and secondary fractures associated with later stage yielded homogenization temperatures (320 ∼ 411℃ and 218 ∼ 332 ℃, respectively) and salinities (0.4 ∼ 4.2 wt% NaCl equivalents and 0.7 ∼ 3.9 wt% NaCl equivalents, respectively). Combined with quartz titanium thermometer results, the high temperature and low salinity ranges of liquid-rich two-phase fluid inclusion in quartz of stage 1 indicate that the ore-forming fluid originated from magmatic vapor, which contracted into an aqueous liquid by cooling at elevated lithostatic pressure above the critical curve of the salt-water fluid system. The δD<sub>V-SMOW</sub> values of stage1 quartz range from − 69.9 ‰ to − 60.9 ‰, with δ<sup>18</sup>O<sub>H2O</sub>‰ values between − 0.9 ‰ and 1.4 ‰, implying the auriferous fluids derive from a magmatic with minor meteoric mixed source. The δ<sup>34</sup>S<sub>V–CDT</sub> values of pyrite of stage 1 and 2 range from –0.3 to 8.0 ‰, revealing that sulfur mainly originates from the magma. The microthermometric data and quartz composition evolution suggest a fluid mixing contribution to metal precipitation. Combined with the geology, gangue and ore mineral assemblage, alteration, fluid inclusion, and H–O–S isotopic characteristics, we propose that the auriferous ore-forming fluids of the Dongji deposit may be the product of magma vapor contraction and migration in a porphyry–epithermal transitional gold system. These findings also indicate a great prospecting potential for the porphyry type mineralization at depth.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106495"},"PeriodicalIF":3.2,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402839","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 : 2025-02-06DOI: 10.1016/j.oregeorev.2025.106489
Filip Simán , Nils Jansson , Foteini Simistira Liwicki , Erik Nordfeldt , Mac Fjellerad Persson , Lena Albrecht , Christian Günther , Paul McDonnell , Tobias Hermansson
Many base and precious metals are sourced from volcanic massive sulphide (VMS) deposits and understanding the geological characteristics of such deposits is crucial for new discoveries of this deposit type. Although key geological characteristics of modern VMS systems are relatively well understood, a remaining challenge is resolving the same geological characteristics in ancient, complex, altered and metamorphosed VMS deposits. One such deposit is the Palaeoproterozoic Rävliden North deposit, an 8.7 Mt (combined resources and reserves of 3.42 % Zn, 0.90 % Cu, 0.54 % Pb, 81 g/t Ag, and 0.24 g/t Au) replacement-style volcanic massive sulphide deposit in the felsic-bimodal western Skellefte district, northern Sweden. The VMS deposits in the Skellefte district are hosted in rocks subjected to greenschist to amphibolite facies metamorphism and occur at the lithostratigraphic contact between the metavolcanic 1.89 – 1.88 Ga Skellefte group (SG) and stratigraphically overlying metasiliciclastic 1.89 – 1.87 Ga Vargfors group (VG). Intense hydrothermal alteration commonly eradicates original rock textures, and polyphase deformation and metamorphism make geological interpretation and stratigraphic reconstruction difficult. Hence, to complement lithofacies analysis, immobile element chemostratigraphy is used in this study.
Rävliden North is predominantly hosted by felsic volcanic rocks of the herein defined Rävliden formation in the upper part of the SG that were deposited in half grabens related to rifting of a continental arc. Based on immobile elements and their ratios the felsic rocks fall into three groups, Rhy I, II and III. The chemostratigraphy and lithostratigraphy roughly coincide, where Rhy II (Zr/Al2O3 = 12.86, Al2O3/TiO2 = 36.07, Zr/TiO2 = 0.05) defines the rhyolites beneath the Rävliden formation that predominantly comprises Rhy I (Zr/Al2O3 = 17.23, Al2O3/TiO2 = 32.33, Zr/TiO2 = 0.06) and Rhy III (Zr/Al2O3 = 17.95, Al2O3/TiO2 = 36.53, Zr/TiO2 = 0.07), where Rhy I is the chief host to mineralisation. Mineralisation is partially hosted by graphitic phyllite that overlies the Rävliden formation and represents the base of the VG that indicates paused volcanism important for the build-up of massive sulphides beneath the seafloor. Facies analysis of rhyolites suggest that these were unconsolidated pumice rich rocks permeable for the upwelling hydrothermal fluids. Additionally, graphitic phyllite functioned as a permeability barrier inducing lateral fluid flow resulting in more effective sulphide precipitation.
This study demonstrates the effectiveness of combining stratigraphic, facies and chemostratigraphic analysis for targeting VMS deposits in complex, altered and metamorphosed rocks.
{"title":"Stratigraphy, facies, and chemostratigraphy at the Palaeoproterozoic Rävliden North Zn-Pb-Ag-Cu VMS deposit, Skellefte district, Sweden","authors":"Filip Simán , Nils Jansson , Foteini Simistira Liwicki , Erik Nordfeldt , Mac Fjellerad Persson , Lena Albrecht , Christian Günther , Paul McDonnell , Tobias Hermansson","doi":"10.1016/j.oregeorev.2025.106489","DOIUrl":"10.1016/j.oregeorev.2025.106489","url":null,"abstract":"<div><div>Many base and precious metals are sourced from volcanic massive sulphide (VMS) deposits and understanding the geological characteristics of such deposits is crucial for new discoveries of this deposit type. Although key geological characteristics of modern VMS systems are relatively well understood, a remaining challenge is resolving the same geological characteristics in ancient, complex, altered and metamorphosed VMS deposits. One such deposit is the Palaeoproterozoic Rävliden North deposit, an 8.7 Mt (combined resources and reserves of 3.42 % Zn, 0.90 % Cu, 0.54 % Pb, 81 g/t Ag, and 0.24 g/t Au) replacement-style volcanic massive sulphide deposit in the felsic-bimodal western Skellefte district, northern Sweden. The VMS deposits in the Skellefte district are hosted in rocks subjected to greenschist to amphibolite facies metamorphism and occur at the lithostratigraphic contact between the metavolcanic 1.89 – 1.88 Ga Skellefte group (SG) and stratigraphically overlying metasiliciclastic 1.89 – 1.87 Ga Vargfors group (VG). Intense hydrothermal alteration commonly eradicates original rock textures, and polyphase deformation and metamorphism make geological interpretation and stratigraphic reconstruction difficult. Hence, to complement lithofacies analysis, immobile element chemostratigraphy is used in this study.</div><div>Rävliden North is predominantly hosted by felsic volcanic rocks of the herein defined Rävliden formation in the upper part of the SG that were deposited in half grabens related to rifting of a continental arc. Based on immobile elements and their ratios the felsic rocks fall into three groups, Rhy I, II and III. The chemostratigraphy and lithostratigraphy roughly coincide, where Rhy II (Zr/Al<sub>2</sub>O<sub>3</sub> = 12.86, Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> = 36.07, Zr/TiO<sub>2</sub> = 0.05) defines the rhyolites beneath the Rävliden formation that predominantly comprises Rhy I (Zr/Al<sub>2</sub>O<sub>3</sub> = 17.23, Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> = 32.33, Zr/TiO<sub>2</sub> = 0.06) and Rhy III (Zr/Al<sub>2</sub>O<sub>3</sub> = 17.95, Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> = 36.53, Zr/TiO<sub>2</sub> = 0.07), where Rhy I is the chief host to mineralisation. Mineralisation is partially hosted by graphitic phyllite that overlies the Rävliden formation and represents the base of the VG that indicates paused volcanism important for the build-up of massive sulphides beneath the seafloor. Facies analysis of rhyolites suggest that these were unconsolidated pumice rich rocks permeable for the upwelling hydrothermal fluids. Additionally, graphitic phyllite functioned as a permeability barrier inducing lateral fluid flow resulting in more effective sulphide precipitation.</div><div>This study demonstrates the effectiveness of combining stratigraphic, facies and chemostratigraphic analysis for targeting VMS deposits in complex, altered and metamorphosed rocks.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106489"},"PeriodicalIF":3.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395168","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 : 2025-02-04DOI: 10.1016/j.oregeorev.2025.106484
Yang Lin , Jing Li , Xuanphu Nguyen , Yuan Wang , Vanlong Hoang , Xinguo Zhuang , Xin Luo , Junyou Hou
Research on critical metals in coal has aroused much interest because some coals are highly enriched in critical metals (Ge, Ga, Li, U, Nb, Ta, Zr, Hf, etc.), and consequently their corresponding coal combustion products may provide an alternative source for these elements. As two critical metals that plays important roles in a wide range of modern industries and various technological applications, Rb and Cs has been found enriched in the upper Triassic coal from the Cam Pha coalfield, NE Vietnam. However, the modes of occurrence and enrichment origin of Rb and Cs in the Cam Pha coal remains unclear. Based on the integrated mineralogical and geochemical analyses of the upper Triassic coals from the Duong Huy and Cao Son open-pit mines in the Cam Pha coalfield, this study focuses on investigating the enrichment and economic potential of rubidium and cesium in these coals. The Nos. 13, 14 and 15 coals from the Cam Pha coalfield are characterized by low-medium ash yield, low volatile matter yield and low sulfur content, belonging to anthracite. In comparison with the world hard coals, Rb and Cs is enriched in the No. 14 coal (Rb and Cs up to 142.8 mg/kg and 12.4 mg/kg, respectively) from Cao Son open-pit mine, as well as in non-coal rocks of No.13 coal (Rb and Cs up to 332.0 mg/kg and 26.4 mg/kg, respectively) and in the No. 15 coal from Duong Huy open-pit mine (Rb and Cs up to 128.5 mg/kg and 13.4 mg/kg, respectively). Rb and Cs mainly occur in K-rich aluminosilicates, such as muscovite in the three coal seams. The enrichment of Rb and Cs in coals from the Cam Pha coalfield is primarily ascribed to the terrigenous supply from the feldspar and mica-rich original felsic rocks in surrounding areas, which migrated into the coal basin through weathering processes during the coalification stage. The acidic anaerobic freshwater environments and the hydrothermal activity are also favorable for the enrichment of Rb and Cs in the study area. Rb and Cs are further enriched in coal fly ashes, reaching the industrial or marginal grade and presenting a promising economic potential for recovery of Rb and Cs from these coals.
{"title":"Enrichment of rubidium and cesium in upper Triassic coals from the Cam Pha coalfield, NE Vietnam: Implications on sediment source and hydrothermal influence","authors":"Yang Lin , Jing Li , Xuanphu Nguyen , Yuan Wang , Vanlong Hoang , Xinguo Zhuang , Xin Luo , Junyou Hou","doi":"10.1016/j.oregeorev.2025.106484","DOIUrl":"10.1016/j.oregeorev.2025.106484","url":null,"abstract":"<div><div>Research on critical metals in coal has aroused much interest because some coals are highly enriched in critical metals (Ge, Ga, Li, U, Nb, Ta, Zr, Hf, etc.), and consequently their corresponding coal combustion products may provide an alternative source for these elements. As two critical metals that plays important roles in a wide range of modern industries and various technological applications, Rb and Cs has been found enriched in the upper Triassic coal from the Cam Pha coalfield, NE Vietnam. However, the modes of occurrence and enrichment origin of Rb and Cs in the Cam Pha coal remains unclear. Based on the integrated mineralogical and geochemical analyses of the upper Triassic coals from the Duong Huy and Cao Son open-pit mines in the Cam Pha coalfield, this study focuses on investigating the enrichment and economic potential of rubidium and cesium in these coals. The Nos. 13, 14 and 15 coals from the Cam Pha coalfield are characterized by low-medium ash yield, low volatile matter yield and low sulfur content, belonging to anthracite. In comparison with the world hard coals, Rb and Cs is enriched in the No. 14 coal (Rb and Cs up to 142.8 mg/kg and 12.4 mg/kg, respectively) from Cao Son open-pit mine, as well as in non-coal rocks of No.13 coal (Rb and Cs up to 332.0 mg/kg and 26.4 mg/kg, respectively) and in the No. 15 coal from Duong Huy open-pit mine (Rb and Cs up to 128.5 mg/kg and 13.4 mg/kg, respectively). Rb and Cs mainly occur in K-rich aluminosilicates, such as muscovite in the three coal seams. The enrichment of Rb and Cs in coals from the Cam Pha coalfield is primarily ascribed to the terrigenous supply from the feldspar and mica-rich original felsic rocks in surrounding areas, which migrated into the coal basin through weathering processes during the coalification stage. The acidic anaerobic freshwater environments and the hydrothermal activity are also favorable for the enrichment of Rb and Cs in the study area. Rb and Cs are further enriched in coal fly ashes, reaching the industrial or marginal grade and presenting a promising economic potential for recovery of Rb and Cs from these coals.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106484"},"PeriodicalIF":3.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143289838","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 : 2025-02-04DOI: 10.1016/j.oregeorev.2025.106469
Katharina Wulff , Robert Bolhar
<div><div>Whole rock geochemistry is presented for lithologically-varied igneous and <em>meta</em>-sedimentary rocks associated with the Bisie tin deposit, and combined with geochronological data and petrographic and field-based observations to develop insights into tectono-magmatic environment(s) of deposition as well physico-chemical conditions and timing of ore mineralisation.</div><div>Bisie tin mine, located in the Mesoproterozoic Kivu Belt (Democratic Republic of the Congo), is the world’s highest-grade tin mine (average grade 4.5 % Sn). Tin mineralisation consists of botryoidal cassiterite veins within an envelope of chlorite alteration, and is situated in a steeply east-dipping shear zone running parallel to the contact to a multi-phase granite massif. The hosting sequence comprises: A lowermost unit, hosting the tin mineralisation and containing mica schists with intercalations of sandstones, felsic tuffs and metabasaltic flows as well as (meta-)gabbro intrusions. Meter-scale pyrite-pyrrhotite-sphalerite-galena lenses of presumed <em>syn</em>-sedimenatry exhalative origin are intercalated in the vicinity of the Bisie deposit. An overlying “metasedimentary unit” comprises tuffaceous shales, siltstones, sandstones and conglomerates. The uppermost unit consists of carbonaceous shales. Peak metamorphic grades in the mica schists are recorded by staurolite-garnet-biotite paragenesis, and decrease towards the top of the sequence and away from the granite massif based on the absence of metamorphic porphyroblasts in the carbonaceous shale. Along the shear zone, peak metamorphic parageneses retrogressed to muscovite (±chlorite) in an alteration zone with a length of > 14 km, which also coincides with a soil Sn anomaly.</div><div>Zircon U-Pb information regarding the granitoid massif includes a granite age of 1518 Ma (pre-Kibaran), a marginal monzogranite age of 1274–1271 Ma and gneissic granite age of ca. 1000 Ma. Cassiterite from Bisie was previously dated at 1068–1029 Ma, consistent with formation during the G4 granite stage, associated with Sn, Nb-Ta, W and Au mineralisation across the Kibaride Belt.</div><div>Trace element signatures of the monzogranite as well as the metabasites indicate formation in an intraplate setting, consistent with deposition of central Kivu Belt rocks in an extensional basin during Cycle 2 of the Kibaran Orogeny. Compositions of the mica schist and carbonaceous shale indicate both collisional and rift environments, probably pointing to mixed sources. Similarity in trace element signatures prove that the chlorite schists, forming the alteration of the Bisie tin deposit, are alteration products derived from the hosting mica schists. All altered and unaltered metasedimentary samples as well as the monzogranite have positive Sn and negative Sr and Ba anomalies in Primitive Mantle normalisation, with the most pronounced anomalies observed in the chlorite schists, probably representing an alteration halo associated with
{"title":"Geochemistry of alteration and host rock lithologies to the Bisie tin deposit, North Kivu Province, DR Congo","authors":"Katharina Wulff , Robert Bolhar","doi":"10.1016/j.oregeorev.2025.106469","DOIUrl":"10.1016/j.oregeorev.2025.106469","url":null,"abstract":"<div><div>Whole rock geochemistry is presented for lithologically-varied igneous and <em>meta</em>-sedimentary rocks associated with the Bisie tin deposit, and combined with geochronological data and petrographic and field-based observations to develop insights into tectono-magmatic environment(s) of deposition as well physico-chemical conditions and timing of ore mineralisation.</div><div>Bisie tin mine, located in the Mesoproterozoic Kivu Belt (Democratic Republic of the Congo), is the world’s highest-grade tin mine (average grade 4.5 % Sn). Tin mineralisation consists of botryoidal cassiterite veins within an envelope of chlorite alteration, and is situated in a steeply east-dipping shear zone running parallel to the contact to a multi-phase granite massif. The hosting sequence comprises: A lowermost unit, hosting the tin mineralisation and containing mica schists with intercalations of sandstones, felsic tuffs and metabasaltic flows as well as (meta-)gabbro intrusions. Meter-scale pyrite-pyrrhotite-sphalerite-galena lenses of presumed <em>syn</em>-sedimenatry exhalative origin are intercalated in the vicinity of the Bisie deposit. An overlying “metasedimentary unit” comprises tuffaceous shales, siltstones, sandstones and conglomerates. The uppermost unit consists of carbonaceous shales. Peak metamorphic grades in the mica schists are recorded by staurolite-garnet-biotite paragenesis, and decrease towards the top of the sequence and away from the granite massif based on the absence of metamorphic porphyroblasts in the carbonaceous shale. Along the shear zone, peak metamorphic parageneses retrogressed to muscovite (±chlorite) in an alteration zone with a length of > 14 km, which also coincides with a soil Sn anomaly.</div><div>Zircon U-Pb information regarding the granitoid massif includes a granite age of 1518 Ma (pre-Kibaran), a marginal monzogranite age of 1274–1271 Ma and gneissic granite age of ca. 1000 Ma. Cassiterite from Bisie was previously dated at 1068–1029 Ma, consistent with formation during the G4 granite stage, associated with Sn, Nb-Ta, W and Au mineralisation across the Kibaride Belt.</div><div>Trace element signatures of the monzogranite as well as the metabasites indicate formation in an intraplate setting, consistent with deposition of central Kivu Belt rocks in an extensional basin during Cycle 2 of the Kibaran Orogeny. Compositions of the mica schist and carbonaceous shale indicate both collisional and rift environments, probably pointing to mixed sources. Similarity in trace element signatures prove that the chlorite schists, forming the alteration of the Bisie tin deposit, are alteration products derived from the hosting mica schists. All altered and unaltered metasedimentary samples as well as the monzogranite have positive Sn and negative Sr and Ba anomalies in Primitive Mantle normalisation, with the most pronounced anomalies observed in the chlorite schists, probably representing an alteration halo associated with","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106469"},"PeriodicalIF":3.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453985","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 : 2025-02-03DOI: 10.1016/j.oregeorev.2025.106488
Aye Pyae Phyo , Huan Li , Xiao-Jun Hu , Majid Ghaderi , Aung Zaw Myint , Mohamed Faisal
Critical metals, particularly tin and tungsten, are essential to global economic development and modern civilization. The Southeast Asian Tin Belt, extending 2800 km, represents the world’s most significant W–Sn metallogenic belt. This belt includes four metallogenic provinces: the Main Range Granitoid Province, the Northern Granitoid Province (North Thailand Migmatitic Province), the Eastern Granitoid Province, and the Western Granitoid Province), with ore assemblages predominantly associated with Phanerozoic intrusions. The Western Granitoid Province of southern Myanmar hosts numerous W-Sn mineralized granitoids, among which we investigated the Nanthila and Pedet granitic plutons in the Myeik Sn-W district. The study area consists primarily of the Carboniferous-Permian Mergui Group and Early Tertiary granitic rocks. The petrogenesis, tectonic setting, magmatic evolution, and the age of the Nanthila and Pedet granitic intrusions remain poorly constrained. This contribution reports field observations, petrographic studies, whole-rock geochemical analyses, in-situ U-Pb zircon dating, Lu-Hf isotopic data, and mineral chemistry analysis. Petrographic and geochemical data reveal that both plutons exhibit high SiO2 (74.63–76.43 wt%), low CaO (0.62–0.73 wt%) and MgO (0.02–0.13 wt%) contents, elevated 10000*Ga/Al ratios (2.94–3.67), mildly peraluminous nature (A/CNK < 1.1), and high-K calc-alkaline affinity. They show high HFSEs concentrations (Y: 8.1–14.8 ppm, Nb: 25.3–40.4 ppm, Th: 41.9–103 ppm, and U: 19.8–29.7 ppm) and moderate to high melting temperatures (zircon: 731–806 °C; apatite: 709–813 °C). These characteristics align with highly fractionated aluminous A2-type granites, displaying “V” type REE distribution patterns with pronounced negative Eu anomalies. The Sn-related granitic magmas likely originated from the partial melting of clay-rich felsic crustal sources under reduced conditions and high temperatures in a post-collisional tectonic setting. Magmatic zircons from six granitoid samples yielded Concordia ages of ∼ 50.78 ± 0.47 Ma to 51.46 ± 0.43 Ma (Eocene period). The 176Hf/177Hf ratios (0.282271 to 0.282541), negative εHf(t) values (−7.18 to −16.74), and two-stage crustal model ages (TDMC) (1.58–2.01) indicate derivation from Neoproterozoic continental crust. These findings highlight the potential of the Nanthila and Pedet areas for further geological investigation and mineral exploration, suggesting they could be promising sites for new reserves.
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