Pub Date : 2025-02-18DOI: 10.1016/j.oregeorev.2025.106496
Chenmeng Li , Huadong Ma , Chuan Chen , Ping Li , Fang Xia , Lingling Gao , Wei Wang , Xiaofei Du , Yongqi Hao , Shunda Li
The central Altyn region in Xinjiang is a prospective region for the mineralization of rare metals, such as lithium and beryllium, and is the target area for the exploration of rare metal deposits of the granitic pegmatite type in this study. However, harsh natural conditions complicate the effective identification of pegmatite dikes via conventional techniques, thereby limiting exploration. The narrowness of pegmatite dikes and aeolian sand cover presents challenge, yet remote sensing technology holds significant potential in this area. High spatial resolution data are essential, and a systematic remote sensing identification method has yet to be established. In this study, we established a spectral library of rocks and minerals in the research area and applied image enhancement techniques such as PCA, ICA, MNF, and band ratios to WorldView-3 imagery. By optimizing the display with RGB combinations, 764 pegmatite dikes were successfully identified, and five pegmatite dike group areas were delineated. A “dike-centered limited buffer” method for identifying mineralized pegmatite dikes was proposed. Using measured spectra combined with the spectral angle mapper (SAM) method, lithium-beryllium-bearing dikes were differentiated from non-lithium-beryllium-bearing dikes, and ultimately, 58 lithium-beryllium-bearing pegmatite dikes were identified. Field validation in Areas III, IV, and V indicates that the identification results align well with on-site observations. In this study, we significantly improved the accuracy of pegmatite dike identification in the central Altyn region, providing an effective remote sensing technique and theoretical support for rare metal exploration in this area.
{"title":"Identification of pegmatite dikes based on remote sensing spectral library and WorldView-3 Data: A Case study in the central Altyn region of Xinjiang","authors":"Chenmeng Li , Huadong Ma , Chuan Chen , Ping Li , Fang Xia , Lingling Gao , Wei Wang , Xiaofei Du , Yongqi Hao , Shunda Li","doi":"10.1016/j.oregeorev.2025.106496","DOIUrl":"10.1016/j.oregeorev.2025.106496","url":null,"abstract":"<div><div>The central Altyn region in Xinjiang is a prospective region for the mineralization of rare metals, such as lithium and beryllium, and is the target area for the exploration of rare metal deposits of the granitic pegmatite type in this study. However, harsh natural conditions complicate the effective identification of pegmatite dikes via conventional techniques, thereby limiting exploration. The narrowness of pegmatite dikes and aeolian sand cover presents challenge, yet remote sensing technology holds significant potential in this area. High spatial resolution data are essential, and a systematic remote sensing identification method has yet to be established. In this study, we established a spectral library of rocks and minerals in the research area and applied image enhancement techniques such as PCA, ICA, MNF, and band ratios to WorldView-3 imagery. By optimizing the display with RGB combinations, 764 pegmatite dikes were successfully identified, and five pegmatite dike group areas were delineated. A “dike-centered limited buffer” method for identifying mineralized pegmatite dikes was proposed. Using measured spectra combined with the spectral angle mapper (SAM) method, lithium-beryllium-bearing dikes were differentiated from non-lithium-beryllium-bearing dikes, and ultimately, 58 lithium-beryllium-bearing pegmatite dikes were identified. Field validation in Areas III, IV, and V indicates that the identification results align well with on-site observations. In this study, we significantly improved the accuracy of pegmatite dike identification in the central Altyn region, providing an effective remote sensing technique and theoretical support for rare metal exploration in this area.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106496"},"PeriodicalIF":3.2,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437967","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 : 2025-02-03DOI: 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.
{"title":"Geology, geochemistry, and zircon U-Pb geochronology of the Nanthila and Pedet granites in the Myeik Sn-W district, Tanintharyi region, southern Myanmar","authors":"Aye Pyae Phyo , Huan Li , Xiao-Jun Hu , Majid Ghaderi , Aung Zaw Myint , Mohamed Faisal","doi":"10.1016/j.oregeorev.2025.106488","DOIUrl":"10.1016/j.oregeorev.2025.106488","url":null,"abstract":"<div><div>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 SiO<sub>2</sub> (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 A<sub>2</sub>-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 <sup>176</sup>Hf/<sup>177</sup>Hf ratios (0.282271 to 0.282541), negative εHf(t) values (−7.18 to −16.74), and two-stage crustal model ages (T<sub>DMC</sub>) (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.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106488"},"PeriodicalIF":3.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148387","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.2025.106487
Guochao Chen , Xiaofei Zhang , Xianzhi Pei , Ruibao Li , Zuochen Li , Junqi Wei , Rongzhen Zhang
Numerous granitic pegmatite dikes intrude the Wuduoshan batholith in the eastern North Qinling orogen (NQ). However, the petrogenesis, interrelationships, and geodynamic setting of these granitoids and associated dikes remain poorly understood. This study investigates the Erlangchuan and Sikeshu plutons and their related dikes in the Qinling orogen, central China, through integrated petrographic, whole-rock geochemical, zircon U-Pb geochronological, and Lu-Hf isotopic analyses. Zircon U-Pb dating yielded crystallization ages of 430.8 ± 2.0 Ma for the Erlangchuan monzogranites, 415.2 ± 1.7 Ma for associated biotite granitic pegmatites, 416.9 ± 2.2 Ma for associated aplite dikes, and 403.6 ± 4.7 Ma for Sikeshu muscovite granitic pegmatites. All samples display geochemical characteristics consistent with a crustal origin, showing enrichment of large-ion lithophile elements (LILE; e.g., Rb, Th, Ba, and Cs) and depletion of high field strength elements (HFSE; e.g., Nb, Ta, and Ti). The granitic dikes exhibit higher SiO2 contents compared to their respective host plutons: the K-rich Erlangchuan monzogranites and the Na-rich, two-mica Sikeshu granites. Zircon Lu-Hf isotopic data reveal higher εHf(t) values for the Erlangchuan monzogranites (average = +2.6) compared to the associated biotite pegmatites (+2.0), aplites (+1.6), and the Sikeshu muscovite pegmatites (+0.9). The εHf(t) values of both plutons and their dikes fall between those of the Qinling Group and juvenile mafic crust, suggesting derivation from a mixed source. Variations in εHf(t) values likely reflect differing proportions of these two endmembers. The Erlangchuan monzogranites formed via partial melting of the lower crust, triggered by mafic magma underplating during Shangdan Ocean subduction. The Sikeshu two-mica granites, associated aplites, and biotite pegmatites likely formed during subsequent collision and slab break-off. Finally, the Sikeshu muscovite pegmatites may represent a later magmatic pulse related to post-collisional lithospheric delamination. Regionally, granitic pegmatites in the eastern NQ define three distinct age peaks at 437 Ma, 413 Ma, and 367 Ma. These pegmatites can be broadly classified into two series: (1) a rare metal-bearing series, predominantly located in the northern eastern NQ, enriched in Nb, Ta, Be, Rb, Li, and Cs, and characterized by negative εHf(t) values indicative of a Qinling Group source; and (2) a U-bearing series, primarily found in the southern eastern NQ, positive or slightly negative εHf(t) values, suggesting derivation from a mixed Qinling Group and juvenile crustal source.
{"title":"Multi-stage granite and granitic pegmatites in the eastern North Qinling orogen: Petrogenesis, geodynamic setting, and metallogenic potential","authors":"Guochao Chen , Xiaofei Zhang , Xianzhi Pei , Ruibao Li , Zuochen Li , Junqi Wei , Rongzhen Zhang","doi":"10.1016/j.oregeorev.2025.106487","DOIUrl":"10.1016/j.oregeorev.2025.106487","url":null,"abstract":"<div><div>Numerous granitic pegmatite dikes intrude the Wuduoshan batholith in the eastern North Qinling orogen (NQ). However, the petrogenesis, interrelationships, and geodynamic setting of these granitoids and associated dikes remain poorly understood. This study investigates the Erlangchuan and Sikeshu plutons and their related dikes in the Qinling orogen, central China, through integrated petrographic, whole-rock geochemical, zircon U-Pb geochronological, and Lu-Hf isotopic analyses. Zircon U-Pb dating yielded crystallization ages of 430.8 ± 2.0 Ma for the Erlangchuan monzogranites, 415.2 ± 1.7 Ma for associated biotite granitic pegmatites, 416.9 ± 2.2 Ma for associated aplite dikes, and 403.6 ± 4.7 Ma for Sikeshu muscovite granitic pegmatites. All samples display geochemical characteristics consistent with a crustal origin, showing enrichment of large-ion lithophile elements (LILE; e.g., Rb, Th, Ba, and Cs) and depletion of high field strength elements (HFSE; e.g., Nb, Ta, and Ti). The granitic dikes exhibit higher SiO<sub>2</sub> contents compared to their respective host plutons: the K-rich Erlangchuan monzogranites and the Na-rich, two-mica Sikeshu granites. Zircon Lu-Hf isotopic data reveal higher ε<sub>Hf</sub>(t) values for the Erlangchuan monzogranites (average = +2.6) compared to the associated biotite pegmatites (+2.0), aplites (+1.6), and the Sikeshu muscovite pegmatites (+0.9). The ε<sub>Hf</sub>(t) values of both plutons and their dikes fall between those of the Qinling Group and juvenile mafic crust, suggesting derivation from a mixed source. Variations in ε<sub>Hf</sub>(t) values likely reflect differing proportions of these two endmembers. The Erlangchuan monzogranites formed via partial melting of the lower crust, triggered by mafic magma underplating during Shangdan Ocean subduction. The Sikeshu two-mica granites, associated aplites, and biotite pegmatites likely formed during subsequent collision and slab break-off. Finally, the Sikeshu muscovite pegmatites may represent a later magmatic pulse related to post-collisional lithospheric delamination. Regionally, granitic pegmatites in the eastern NQ define three distinct age peaks at 437 Ma, 413 Ma, and 367 Ma. These pegmatites can be broadly classified into two series: (1) a rare metal-bearing series, predominantly located in the northern eastern NQ, enriched in Nb, Ta, Be, Rb, Li, and Cs, and characterized by negative ε<sub>Hf</sub>(t) values indicative of a Qinling Group source; and (2) a U-bearing series, primarily found in the southern eastern NQ, positive or slightly negative ε<sub>Hf</sub>(t) values, suggesting derivation from a mixed Qinling Group and juvenile crustal source.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"178 ","pages":"Article 106487"},"PeriodicalIF":3.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143289839","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}
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