Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106319
Jun-Jie Hu , Ru-Xiong Lei , Matthew J. Brzozowski , Chang-Zhi Wu
Rare-metal granites result from a combination of magmatic and hydrothermal processes. The mineralogical, textural, and chemical characteristics of columbite-group minerals (CGMs), which are ubiquitous in rare-metal granites and pegmatites, can serve as records of the magmatic–hydrothermal processes responsible for the evolution of these granitic systems. The highly evolved Baishitouquan (BST) granite pluton, located in the Eastern Tianshan of NW China, hosts the large-scale Zhangbaoshan (ZBS) Rb deposit (Rb2O reserve of 67080 t), making it of economic significance. The BST pluton comprises a series of gradual lithological zones, which, from bottom to top, are leucogranite (Zone-a), amazonite-bearing granite (Zone-b), amazonite granite (Zone-c), topaz-bearing amazonite granite (Zone-d), topaz albite granite (Zone-e), and amazonite pegmatite veins. Based on textural and chemical characteristics, five types of CGMs were identified — CGMs with no zoning, and oscillatory zoned, normally zoned, hydrothermally overprinted, and patchy CGMs. The CGMs that exhibit no zoning, oscillatory zoning, and normal zoning mainly occur in Zones-a to -c, suggesting that the lithological and geochemical variations in these zones formed as a result of the magmatic evolution of the BST magma. Hydrothermally overprinted CGMs and those with a patchy texture mainly occur in Zones-d and -e, and the pegmatite veins, suggesting that the evolution of these zones involved hydrothermal processes. From Zone-a to Zone-c, the Ta# and Mn# of CGMs increase gradually, suggesting a gradual evolution of the BST magma. The CGMs are characterized by REE tetrad effect (TE1,3) that is consistently greater than 1.1 and increases from Zone-a to the pegmatite veins, indicative of increased melt–fluid interaction during evolution of the BST magma. It is, therefore, suggested that the BST magma evolved not only via high degrees of fractional crystallization, but also by the interaction of the melt with hydrothermal fluids, the latter of which likely originated by exsolution from the evolving melt. Based on the mineralogical, textural, and chemical characteristics of CGMs in the BST pluton, a petrogenetic model is proposed to explain the magmatic–hydrothermal evolution of the BST granitic magma.
{"title":"Textures and chemistry of columbite-group minerals record magmatic–hydrothermal processes in the Baishitouquan pluton in the Eastern Tianshan, NW China","authors":"Jun-Jie Hu , Ru-Xiong Lei , Matthew J. Brzozowski , Chang-Zhi Wu","doi":"10.1016/j.oregeorev.2024.106319","DOIUrl":"10.1016/j.oregeorev.2024.106319","url":null,"abstract":"<div><div>Rare-metal granites result from a combination of magmatic and hydrothermal processes. The mineralogical, textural, and chemical characteristics of columbite-group minerals (CGMs), which are ubiquitous in rare-metal granites and pegmatites, can serve as records of the magmatic–hydrothermal processes responsible for the evolution of these granitic systems. The highly evolved Baishitouquan (BST) granite pluton, located in the Eastern Tianshan of NW China, hosts the large-scale Zhangbaoshan (ZBS) Rb deposit (Rb<sub>2</sub>O reserve of 67080 t), making it of economic significance. The BST pluton comprises a series of gradual lithological zones, which, from bottom to top, are leucogranite (Zone-a), amazonite-bearing granite (Zone-b), amazonite granite (Zone-c), topaz-bearing amazonite granite (Zone-d), topaz albite granite (Zone-e), and amazonite pegmatite veins. Based on textural and chemical characteristics, five types of CGMs were identified — CGMs with no zoning, and oscillatory zoned, normally zoned, hydrothermally overprinted, and patchy CGMs. The CGMs that exhibit no zoning, oscillatory zoning, and normal zoning mainly occur in Zones-a to -c, suggesting that the lithological and geochemical variations in these zones formed as a result of the magmatic evolution of the BST magma. Hydrothermally overprinted CGMs and those with a patchy texture mainly occur in Zones-d and -e, and the pegmatite veins, suggesting that the evolution of these zones involved hydrothermal processes. From Zone-a to Zone-c, the Ta# and Mn# of CGMs increase gradually, suggesting a gradual evolution of the BST magma. The CGMs are characterized by REE tetrad effect (TE<sub>1,3</sub>) that is consistently greater than 1.1 and increases from Zone-a to the pegmatite veins, indicative of increased melt–fluid interaction during evolution of the BST magma. It is, therefore, suggested that the BST magma evolved not only via high degrees of fractional crystallization, but also by the interaction of the melt with hydrothermal fluids, the latter of which likely originated by exsolution from the evolving melt. Based on the mineralogical, textural, and chemical characteristics of CGMs in the BST pluton, a petrogenetic model is proposed to explain the magmatic–hydrothermal evolution of the BST granitic magma.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106319"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106325
Guiyuan Guan , Siwen Li , Rongxi Li , Wei Wang
Many sedimentary metal deposits are rich in organic matter, and some organic deposits are metal deposits themselves. These metal deposits, represented by MVT Zn-Pb deposits, are widely distributed in the world, and their industrial types (Pb + Zn > 5 %) are also very rich, which has important theoretical and economic significance. However, there is no systematic research on the metallogenic mechanism of MVT Zn-Pb deposits in the participating organic matter. Therefore, geochemical simulation experiments and thermodynamic calculations have been used to examine the role of organic matter in reconstructing the ore-forming process of MVT Zn-Pb sulfide deposits. Additionally, the precipitation chemistry of sphalerite under the mineralization process mediated by organic matter is explained. Guided by the evidence on the homogenization temperature of fluid inclusion, the temperature range, from 60 °C to 200 °C, has drawn a close relationship between the temperature and the ore-forming mechanism. Notably, this reflects sphalerite’s chemical composition and morphology, even assisting in interpreting its chemical formation. The results showed that 80 °C is the beginning temperature for ZnS formation calculated from the inductively coupled plasma mass spectrometry analysis (ICP-MS) under the precipitation simulation experiments with the participation of organic matter. With the increased temperature, the rate of ZnS formation showed a trend of rapid growth in the early stage (80–140 °C) and relatively slow in the later stage (160–200 °C). This finding suggests a closer coupling relationship between metal mineralization and the maturation-genesis of organic matter, mainly the formation of the ancient oil reservoir. Following the continued increase in temperature, the morphology of ZnS was significantly different from that of the scanning electron microscope (SEM), with an apparent fine granular structure at high temperature. Likewise, more ZnO was also found through the X-ray photoelectron spectroscopy analysis (XPS), reducing the purity of the ZnS in sphalerite. Thus, this study helps reveal the metallogenic mechanism of MVT Zn-Pb sulfide deposits from the viewpoint of sphalerite chemistry under the participation of organic matter from temperature change. Furthermore, it provides a valuable theoretical and experimental basis for the later prospecting of the metal deposits.
{"title":"Impact of temperature on sphalerite chemistry: Simulation experiments of sphalerite in MVT Zn-Pb sulfide deposits in the Beiba Dome, northern Sichuan Basin, China","authors":"Guiyuan Guan , Siwen Li , Rongxi Li , Wei Wang","doi":"10.1016/j.oregeorev.2024.106325","DOIUrl":"10.1016/j.oregeorev.2024.106325","url":null,"abstract":"<div><div>Many sedimentary metal deposits are rich in organic matter, and some organic deposits are metal deposits themselves. These metal deposits, represented by MVT Zn-Pb deposits, are widely distributed in the world, and their industrial types (Pb + Zn > 5 %) are also very rich, which has important theoretical and economic significance. However, there is no systematic research on the metallogenic mechanism of MVT Zn-Pb deposits in the participating organic matter. Therefore, geochemical simulation experiments and thermodynamic calculations have been used to examine the role of organic matter in reconstructing the ore-forming process of MVT Zn-Pb sulfide deposits. Additionally, the precipitation chemistry of sphalerite under the mineralization process mediated by organic matter is explained. Guided by the evidence on the homogenization temperature of fluid inclusion, the temperature range, from 60 °C to 200 °C, has drawn a close relationship between the temperature and the ore-forming mechanism. Notably, this reflects sphalerite’s chemical composition and morphology, even assisting in interpreting its chemical formation. The results showed that 80 °C is the beginning temperature for ZnS formation calculated from the inductively coupled plasma mass spectrometry analysis (ICP-MS) under the precipitation simulation experiments with the participation of organic matter. With the increased temperature, the rate of ZnS formation showed a trend of rapid growth in the early stage (80–140 °C) and relatively slow in the later stage (160–200 °C). This finding suggests a closer coupling relationship between metal mineralization and the maturation-genesis of organic matter, mainly the formation of the ancient oil reservoir. Following the continued increase in temperature, the morphology of ZnS was significantly different from that of the scanning electron microscope (SEM), with an apparent fine granular structure at high temperature. Likewise, more ZnO was also found through the X-ray photoelectron spectroscopy analysis (XPS), reducing the purity of the ZnS in sphalerite. Thus, this study helps reveal the metallogenic mechanism of MVT Zn-Pb sulfide deposits from the viewpoint of sphalerite chemistry under the participation of organic matter from temperature change. Furthermore, it provides a valuable theoretical and experimental basis for the later prospecting of the metal deposits.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106325"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106308
Hui-Min Su , Yu-Ying Che , Tong Liu , Hua Li , Li Liu , Tao Jin , Shuyue He
The Niukutou deposit, situated within the Qimantagh ore-concentrated area of the East Kunlun Orogenic Belt (EKOB), represents a typical skarn-type Pb-Zn-(Fe) deposit that is also associated with cobalt (Co) mineralization. The main ore minerals include galena, sphalerite, magnetite, hematite, Co-bearing arsenopyrite, cobaltite and glaucodot. This study conducted geochronological and chemical composition analyses of multi-generational garnets from the deposit, aiming to elucidate their genetic significance in the mineralization process. Field and mineralogical observations indicate the presence of three generations of garnets: Grt-I, Grt-II, and Grt-III. The earliest garnet generation (Grt-I) formed during the prograde stage, typically in garnet skarns, and is often replaced by epidote. The second generation (Grt-II), which coexists with pyroxene, also formed during the prograde stage, whereas the third generation (Grt-III) is associated with pyrrhotite stockworks, suggesting its formation during the sulfide stage. Using in-situ LA-ICP-MS U-Pb dating, garnets yield ages of approximately 230–234 Ma, which aligns with the age of 231.8 ± 7.5 Ma obtained from hydrothermal titanite in the deposit. These ages, combined with those of the previous studies, indicate major magmatic and metallogenic activity of 220–240 Ma in the Qimantagh area. Each generation of garnets displays oscillatory zoning characterized by alternating andradite and grossular compositions. The variations in Sn and high field-strength element (HFSE) contents across different garnet generations indicate an increasing trend in oxygen fugacity as mineralization progresses. The high Sn contents in the Niukutou garnets provide geochemical clues for the potential of Sn-W mineralization in this deposit, which should pay attention to in future exploration. Additionally, the high As concentrations in the Niukutou garnets suggest an As-rich hydrothermal fluid, which, owing to the stronger affinity of cobalt for sulfarsenides over sulfides, provides a geochemical indicator for the formation of abundant Co-bearing sulfarsenides rather than cobaltiferous sulfides in the deposit.
牛硐头矿床位于东昆仑造山带（EKOB）祁漫塔格矿石集中区，是典型的矽卡岩型铅锌（铁）矿床，也伴生钴（Co）矿化。主要矿石矿物包括方铅矿、闪锌矿、磁铁矿、赤铁矿、含钴砷黄铁矿、钴矿和萤石。这项研究对矿床中的多代石榴石进行了地质年代和化学成分分析，旨在阐明它们在成矿过程中的遗传意义。野外和矿物学观察表明存在三代石榴石：Grt-I、Grt-II 和 Grt-III。最早的一代石榴石（Grt-I）形成于原生阶段，通常位于石榴石矽卡岩中，经常被表长石所取代。第二代石榴石（Grt-II）与辉石共存，也是在原生阶段形成的，而第三代石榴石（Grt-III）则与黄铁矿堆积物有关，表明它是在硫化物阶段形成的。利用原位 LA-ICP-MS U-Pb 测定法，石榴石的年龄约为 230-234 Ma，这与该矿床热液榍石的年龄 231.8 ± 7.5 Ma 相吻合。这些年龄与之前研究的年龄相结合，表明奇曼塔格地区在 220-240 Ma 期间有大规模的岩浆和金属生成活动。每一代石榴石都显示出振荡分带，其特征是安氏斜长石和毛玻璃成分交替出现。各代石榴石中锡和高场强元素（HFSE）含量的变化表明，随着成矿作用的进行，富氧性呈上升趋势。Niukutou石榴石中的高锡含量为该矿床潜在的锡-钨矿化提供了地球化学线索，在未来的勘探中应加以重视。此外，Niukutou石榴石中的高砷浓度表明富含砷的热液流体，由于钴对硫砷化物的亲和力强于硫化物，这为该矿床形成丰富的含钴硫砷化物而非含钴硫化物提供了地球化学指标。
{"title":"Multiple generations of garnet and their genetic significance in the Niukutou cobalt-rich Pb-Zn-(Fe) skarn deposit, East Kunlun orogenic belt, western China","authors":"Hui-Min Su , Yu-Ying Che , Tong Liu , Hua Li , Li Liu , Tao Jin , Shuyue He","doi":"10.1016/j.oregeorev.2024.106308","DOIUrl":"10.1016/j.oregeorev.2024.106308","url":null,"abstract":"<div><div>The Niukutou deposit, situated within the Qimantagh ore-concentrated area of the East Kunlun Orogenic Belt (EKOB), represents a typical skarn-type Pb-Zn-(Fe) deposit that is also associated with cobalt (Co) mineralization. The main ore minerals include galena, sphalerite, magnetite, hematite, Co-bearing arsenopyrite, cobaltite and glaucodot. This study conducted geochronological and chemical composition analyses of multi-generational garnets from the deposit, aiming to elucidate their genetic significance in the mineralization process. Field and mineralogical observations indicate the presence of three generations of garnets: Grt-I, Grt-II, and Grt-III. The earliest garnet generation (Grt-I) formed during the prograde stage, typically in garnet skarns, and is often replaced by epidote. The second generation (Grt-II), which coexists with pyroxene, also formed during the prograde stage, whereas the third generation (Grt-III) is associated with pyrrhotite stockworks, suggesting its formation during the sulfide stage. Using <em>in-situ</em> LA-ICP-MS U-Pb dating, garnets yield ages of approximately 230–234 Ma, which aligns with the age of 231.8 ± 7.5 Ma obtained from hydrothermal titanite in the deposit. These ages, combined with those of the previous studies, indicate major magmatic and metallogenic activity of 220–240 Ma in the Qimantagh area. Each generation of garnets displays oscillatory zoning characterized by alternating andradite and grossular compositions. The variations in Sn and high field-strength element (HFSE) contents across different garnet generations indicate an increasing trend in oxygen fugacity as mineralization progresses. The high Sn contents in the Niukutou garnets provide geochemical clues for the potential of Sn-W mineralization in this deposit, which should pay attention to in future exploration. Additionally, the high As concentrations in the Niukutou garnets suggest an As-rich hydrothermal fluid, which, owing to the stronger affinity of cobalt for sulfarsenides over sulfides, provides a geochemical indicator for the formation of abundant Co-bearing sulfarsenides rather than cobaltiferous sulfides in the deposit.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106308"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106324
Fu-Rong Li , Yong Zhang , Fei-Peng Dang , Di Huang , Fu-Jun Zhong , Jie Yan , Fei Xia , Chun-Rong Pan , Jia-Yong Pan , Shan-Chu Han , Guo-Qi Liu , Xiao-Tian Zhang , Ying Liu , Kai-Xing Wang
Hydrothermal alteration can be utilized to constrain element migrations during mineralization, as it records the effects of fluid-rock interactions. Previous studies have suggested that uranium in deposits primarily originates from uranium-bearing granites; however, limited knowledge exists regarding the leaching mechamisms of this element and rare earth elements (REEs) from these rocks. In recent years, the Xiaoshan Deposit, a newly discovered medium-sized uranium deposit, has been discovered in the central part of the Lujing uranium ore field, South China. In this study, we examine this deposit to investigate hydrothermal alterations and their impact on elemental mass change. The deposit exhibits seven types of alteration including K-feldspar, albite, illite, sericite, muscovite, quartz and chlorite alteration. These alterations follow a certain sequence, starting from chlorite alteration, followed by widespread K-feldspar alteration, then to albite alteration, accompanied by muscovite alteration, and finally illite, sericite and quartz alteration. The main uranium mineralization stage was coeval with the late acid siliceous hydrothermal fluid, illite and sericite alteration. The pre-ore alkaline alteration (K-feldspar alteration) resulted in the leaching and extraction of uranium, leading to the precipitation of a significant amount of apatite in mineral interstices and initial uranium enrichment (ΔCi (U) = 16.52 ppm). This process facilitated material preparation for subsequent acidic alterations and localized ore enrichment. The original dense rock structure was disrupted, creating fractures/cavities that served as conduits for uranium mineralization. Moreover, under alkaline metasomatism, uranium and REEs was extensively leached out of uranium-bearing accessory minerals such as the apatite. According to apatite compositional variations and alteration geochemistry, these variations reveal the process of uranium dissolution, migration, and precipitation enrichment into ore bodies. Uranium was completely released during alkaline metasomatism, causing a sharp decline in U content from 53.1 ppm to 0.96 ppm. The formation of alkaline alteration fluids facilitates the extraction of uranium from the surrounding rocks (the Indosinian granite).
{"title":"The role of hydrothermal alteration in uranium mineralization at the Xiaoshan uranium deposit, South China","authors":"Fu-Rong Li , Yong Zhang , Fei-Peng Dang , Di Huang , Fu-Jun Zhong , Jie Yan , Fei Xia , Chun-Rong Pan , Jia-Yong Pan , Shan-Chu Han , Guo-Qi Liu , Xiao-Tian Zhang , Ying Liu , Kai-Xing Wang","doi":"10.1016/j.oregeorev.2024.106324","DOIUrl":"10.1016/j.oregeorev.2024.106324","url":null,"abstract":"<div><div>Hydrothermal alteration can be utilized to constrain element migrations during mineralization, as it records the effects of fluid-rock interactions. Previous studies have suggested that uranium in deposits primarily originates from uranium-bearing granites; however, limited knowledge exists regarding the leaching mechamisms of this element and rare earth elements (REEs) from these rocks. In recent years, the Xiaoshan Deposit, a newly discovered medium-sized uranium deposit, has been discovered in the central part of the Lujing uranium ore field, South China. In this study, we examine this deposit to investigate hydrothermal alterations and their impact on elemental mass change. The deposit exhibits seven types of alteration including K-feldspar, albite, illite, sericite, muscovite, quartz and chlorite alteration. These alterations follow a certain sequence, starting from chlorite alteration, followed by widespread K-feldspar alteration, then to albite alteration, accompanied by muscovite alteration, and finally illite, sericite and quartz alteration. The main uranium mineralization stage was coeval with the late acid siliceous hydrothermal fluid, illite and sericite alteration. The pre-ore alkaline alteration (K-feldspar alteration) resulted in the leaching and extraction of uranium, leading to the precipitation of a significant amount of apatite in mineral interstices and initial uranium enrichment (ΔCi (U) = 16.52 ppm). This process facilitated material preparation for subsequent acidic alterations and localized ore enrichment. The original dense rock structure was disrupted, creating fractures/cavities that served as conduits for uranium mineralization. Moreover, under alkaline metasomatism, uranium and REEs was extensively leached out of uranium-bearing accessory minerals such as the apatite. According to apatite compositional variations and alteration geochemistry, these variations reveal the process of uranium dissolution, migration, and precipitation enrichment into ore bodies. Uranium was completely released during alkaline metasomatism, causing a sharp decline in U content from 53.1 ppm to 0.96 ppm. The formation of alkaline alteration fluids facilitates the extraction of uranium from the surrounding rocks (the Indosinian granite).</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106324"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106310
Sanki Biswas, Ofentse M. Moroeng, Nicola J. Wagner
<div><div>Coal is being explored as a potential alternative source for rare earth elements (REY + Sc), which are critical for advancing modern technology. Previous research has mainly focused on assessing the concentration and distribution of REY + Sc in coals from South Africa. However, the modes occurrence of these elements in coal is yet to be investigated. This study offers new insights on the mineralogy and inorganic geochemistry of the No. 6 Seam coal from the Soutpansberg Coalfield (South Africa). The objective is to investigate the distribution, enrichment, and modes of occurrence of critical elements such as Ga, Se, Nb, and REY + Sc within this coal. The No. 6 Seam is a medium rank-B, moderate vitrinite (avg. 41.5 vol%) coal, and contains major minerals such as kaolinite, quartz, and minor minerals including muscovite, siderite, dolomite, pyrite, and calcite. The total REY + Sc concentrations in the coal samples range from 79.9 to 332.1 mg/kg (avg. 213.2 mg/kg; whole-coal/rock basis), higher than global averages for hard coal. The upper continental crust (UCC) normalized concentration coefficients (CC) of the coal shows enrichment of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, and Y. Distinct REY + Sc enrichment patterns are observed across different coal horizons, divided into two categories: light-REY (LREY) and medium-REY (MREY) in the bottom horizon coal [bottom-upper (BU) and bottom-lower (BL)], whereas the middle horizon coal [middle-upper (MU) and middle-lower (ML)] are enriched in medium-REY (MREY) and heavy-REY (HREY). The BU and BL samples show greater REY + Sc enrichment relative to the MU and ML samples. The samples also contain elevated concentrations of Ga (max. 106.1 mg/kg), Se (max. 50.9 mg/kg), and Nb (max. 14.8 mg/kg), exceeding the average values reported for Chinese coals.</div><div>When considering the correlations between REY + Sc and major oxide elements, minerals, and organic petrographic assemblages, REY + Sc appears to be more closely associated with inorganic fraction, particularly aluminosilicate (such as kaolinite) and carbonate minerals (like dolomite), rather than with the organic fraction. The kaolinite and dolomite represent mostly detrital input and epigenesis, respectively. Gallium in the coal is primarily associated with aluminium oxide-hydroxide, Nb with minerals such as clay, rutile/anatase, and zircon; and Se with pyrite. Redox-sensitive elemental ratios of Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> andTiO<sub>2</sub>/Zr suggest that the detrital components of the No. 6 Seam coals were predominantly derived from a source consisting of felsic-intermediate rocks. These materials likely represent the weathering products of magmatic rocks from the passive-continental margin tectonic framework of the Limpopo Mobile Belt. Paleoclimatic conditions are inferred to be warm-humid to hot, with the peat deposited under suboxic-to-oxic environments. High values of critical REY percentage (REY<sub><strong>def,re
煤炭被视为稀土元素（REY + Sc）的潜在替代来源，而稀土元素对现代技术的发展至关重要。以前的研究主要集中在评估南非煤炭中 REY + Sc 的浓度和分布。然而，这些元素在煤炭中的出现模式还有待研究。本研究对南非苏特潘斯贝格煤田 6 号煤层的矿物学和无机地球化学有了新的认识。目的是研究煤中 Ga、Se、Nb 和 REY + Sc 等关键元素的分布、富集和出现模式。6 号煤层是一种中等阶 B、中等玻璃光泽度（平均 41.5 vol%）的煤炭，含有高岭石、石英等主要矿物和麝香石、菱铁矿、白云石、黄铁矿、方解石等次要矿物。煤炭样本中的总 REY + Sc 浓度范围为 79.9 至 332.1 毫克/千克（平均值为 213.2 毫克/千克；全煤/岩石基），高于全球硬煤的平均值。煤的上部大陆地壳（UCC）归一化浓度系数（CC）显示出 La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Er、Yb 和 Y 的富集。在不同煤层中观察到不同的 REY + Sc 富集模式，分为两类：底层煤[底-上（BU）和底-下（BL）]富含轻型 REY（LREY）和中型 REY（MREY），而中层煤[中-上（MU）和中-下（ML）]富含中型 REY（MREY）和重型 REY（HREY）。与 MU 和 ML 样品相比，BU 和 BL 样品显示出更高的 REY + Sc 富集度。这些样品还含有较高浓度的镓（最高 106.1 毫克/千克）、硒（最高 50.9 毫克/千克）和铌（最高 14.8 毫克/千克），超过了中国煤炭报告的平均值。在考虑 REY + Sc 与主要氧化物元素、矿物和有机岩相组合之间的相关性时，REY + Sc 似乎与无机部分，特别是铝硅酸盐（如高岭石）和碳酸盐矿物（如白云石）的关系更为密切，而不是与有机部分的关系。高岭石和白云石分别代表了大部分的碎屑输入和外生成分。煤中的镓主要与氧化铝-氢氧化物有关，铌与粘土、金红石/金红石和锆石等矿物有关，而硒则与黄铁矿有关。Al2O3/TiO2和TiO2/Zr的氧化还原敏感元素比率表明，6号煤层煤炭的碎屑成分主要来自长英质-中英质岩石。这些物质很可能是林波波移动带被动大陆边缘构造框架中岩浆岩的风化产物。古气候条件推断为暖湿至炎热，泥炭沉积在亚缺氧至缺氧环境中。临界 REY 百分比（REYdef,rel%：29.85% 至 39.75%）的高值和展望系数≥ 0.7 表明，这些苏特潘斯贝格煤炭样本有望回收 REY + Sc 和镓。
{"title":"Mineralogy and geochemical controls on the distribution of REY-Ga-Se-Nb enrichment in the No. 6 Coal Seam, Soutpansberg Coalfield, South Africa","authors":"Sanki Biswas, Ofentse M. Moroeng, Nicola J. Wagner","doi":"10.1016/j.oregeorev.2024.106310","DOIUrl":"10.1016/j.oregeorev.2024.106310","url":null,"abstract":"<div><div>Coal is being explored as a potential alternative source for rare earth elements (REY + Sc), which are critical for advancing modern technology. Previous research has mainly focused on assessing the concentration and distribution of REY + Sc in coals from South Africa. However, the modes occurrence of these elements in coal is yet to be investigated. This study offers new insights on the mineralogy and inorganic geochemistry of the No. 6 Seam coal from the Soutpansberg Coalfield (South Africa). The objective is to investigate the distribution, enrichment, and modes of occurrence of critical elements such as Ga, Se, Nb, and REY + Sc within this coal. The No. 6 Seam is a medium rank-B, moderate vitrinite (avg. 41.5 vol%) coal, and contains major minerals such as kaolinite, quartz, and minor minerals including muscovite, siderite, dolomite, pyrite, and calcite. The total REY + Sc concentrations in the coal samples range from 79.9 to 332.1 mg/kg (avg. 213.2 mg/kg; whole-coal/rock basis), higher than global averages for hard coal. The upper continental crust (UCC) normalized concentration coefficients (CC) of the coal shows enrichment of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, and Y. Distinct REY + Sc enrichment patterns are observed across different coal horizons, divided into two categories: light-REY (LREY) and medium-REY (MREY) in the bottom horizon coal [bottom-upper (BU) and bottom-lower (BL)], whereas the middle horizon coal [middle-upper (MU) and middle-lower (ML)] are enriched in medium-REY (MREY) and heavy-REY (HREY). The BU and BL samples show greater REY + Sc enrichment relative to the MU and ML samples. The samples also contain elevated concentrations of Ga (max. 106.1 mg/kg), Se (max. 50.9 mg/kg), and Nb (max. 14.8 mg/kg), exceeding the average values reported for Chinese coals.</div><div>When considering the correlations between REY + Sc and major oxide elements, minerals, and organic petrographic assemblages, REY + Sc appears to be more closely associated with inorganic fraction, particularly aluminosilicate (such as kaolinite) and carbonate minerals (like dolomite), rather than with the organic fraction. The kaolinite and dolomite represent mostly detrital input and epigenesis, respectively. Gallium in the coal is primarily associated with aluminium oxide-hydroxide, Nb with minerals such as clay, rutile/anatase, and zircon; and Se with pyrite. Redox-sensitive elemental ratios of Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> andTiO<sub>2</sub>/Zr suggest that the detrital components of the No. 6 Seam coals were predominantly derived from a source consisting of felsic-intermediate rocks. These materials likely represent the weathering products of magmatic rocks from the passive-continental margin tectonic framework of the Limpopo Mobile Belt. Paleoclimatic conditions are inferred to be warm-humid to hot, with the peat deposited under suboxic-to-oxic environments. High values of critical REY percentage (REY<sub><strong>def,re","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106310"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106275
Stefan S. Andersson , Erik Jonsson , Martiya Sadeghi
<div><div>Rare earth elements (REE) have gained increasing significance for numerous technologies, particularly in today’s rapidly expanding “green transition” applications such as wind generators and electric vehicle traction engines. Among the more well-known REE mineralisation types in Sweden, together with alkaline intrusions and apatite-iron oxide ores, is the classic yet enigmatic REE-Fe-polymetallic mineral system of Bastnäs-type. The mineralisation type is regional in context and occurs in a discontinuous SW–NE-striking belt (the REE-line) in the west-central part of the Palaeoproterozoic Bergslagen ore province, Sweden. This contribution is aimed at integrating and synthesising existing geological, mineralogical, and textural features with new observations from both well-known and several lesser-known, underexplored or previously unrecognised REE-enriched occurrences within this belt, and to discuss key features within the context of mineral systems modelling. A considerable diversity in both the style and abundance of REE mineralisation as well as in discrete REE mineralogy is evident both regionally across the entire REE-line and locally within different ore districts or mine fields. These variations also extend laterally within or across different stratigraphic levels, and within different host rocks, primarily skarn-altered metacarbonates but also variably altered felsic metavolcanic rocks. Many of the mineralisations share similar textural features, which record a protracted evolution with multiple stages of formation or replacement of REE-minerals. The earliest recognised REE assemblages feature fine-grained cerite-(CeCa) with minor bastnäsite-(Ce) – bastnäsite-(La) or fluorbritholite-(Ce) – fluorbritholite-(Y) or locally britholite-(Ce) – britholite-(Y) minerals. Such assemblages typically display anhedral-granoblastic textures appearing in folded assemblages, all suggesting recrystallisation and ductile deformation during regional metamorphism of REE-minerals that had formed during an early stage of the Svecokarelian orogeny. Overprinting overgrowths and cross-cutting vein-like features of allanite-group minerals likely represent different stage(s) of REE mineralisation and (re)-mobilisation during this orogenic evolution. Several of the REE-enriched occurrences contain variably abundant and diverse polymetallic Cu-Mo-Bi-(Co) sulphide mineralisation that typically occur in late paragenetic positions and show a prevalence to REE-rich assemblages, often dominated by different allanite-group minerals. Sulphide and REE mineralisation are locally strongly associated with metamorphic minerals formed during metamorphism of variably Mg-(Fe)-altered metavolcanic rocks. The diversity in style and intensity of the REE mineralisations, along with variations in textures and specific mineralogy, suggest slight differences in the ore-forming conditions or environment at the time of mineralisation. Additionally, these differences may also reflec
{"title":"A synthesis of the REE-Fe-polymetallic mineral system of the REE-line, Bergslagen, Sweden: New mineralogical and textural-paragenetic constraints","authors":"Stefan S. Andersson , Erik Jonsson , Martiya Sadeghi","doi":"10.1016/j.oregeorev.2024.106275","DOIUrl":"10.1016/j.oregeorev.2024.106275","url":null,"abstract":"<div><div>Rare earth elements (REE) have gained increasing significance for numerous technologies, particularly in today’s rapidly expanding “green transition” applications such as wind generators and electric vehicle traction engines. Among the more well-known REE mineralisation types in Sweden, together with alkaline intrusions and apatite-iron oxide ores, is the classic yet enigmatic REE-Fe-polymetallic mineral system of Bastnäs-type. The mineralisation type is regional in context and occurs in a discontinuous SW–NE-striking belt (the REE-line) in the west-central part of the Palaeoproterozoic Bergslagen ore province, Sweden. This contribution is aimed at integrating and synthesising existing geological, mineralogical, and textural features with new observations from both well-known and several lesser-known, underexplored or previously unrecognised REE-enriched occurrences within this belt, and to discuss key features within the context of mineral systems modelling. A considerable diversity in both the style and abundance of REE mineralisation as well as in discrete REE mineralogy is evident both regionally across the entire REE-line and locally within different ore districts or mine fields. These variations also extend laterally within or across different stratigraphic levels, and within different host rocks, primarily skarn-altered metacarbonates but also variably altered felsic metavolcanic rocks. Many of the mineralisations share similar textural features, which record a protracted evolution with multiple stages of formation or replacement of REE-minerals. The earliest recognised REE assemblages feature fine-grained cerite-(CeCa) with minor bastnäsite-(Ce) – bastnäsite-(La) or fluorbritholite-(Ce) – fluorbritholite-(Y) or locally britholite-(Ce) – britholite-(Y) minerals. Such assemblages typically display anhedral-granoblastic textures appearing in folded assemblages, all suggesting recrystallisation and ductile deformation during regional metamorphism of REE-minerals that had formed during an early stage of the Svecokarelian orogeny. Overprinting overgrowths and cross-cutting vein-like features of allanite-group minerals likely represent different stage(s) of REE mineralisation and (re)-mobilisation during this orogenic evolution. Several of the REE-enriched occurrences contain variably abundant and diverse polymetallic Cu-Mo-Bi-(Co) sulphide mineralisation that typically occur in late paragenetic positions and show a prevalence to REE-rich assemblages, often dominated by different allanite-group minerals. Sulphide and REE mineralisation are locally strongly associated with metamorphic minerals formed during metamorphism of variably Mg-(Fe)-altered metavolcanic rocks. The diversity in style and intensity of the REE mineralisations, along with variations in textures and specific mineralogy, suggest slight differences in the ore-forming conditions or environment at the time of mineralisation. Additionally, these differences may also reflec","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106275"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106323
Xiaobin Xu , Xiaoming Sun , Zhengpeng Ding , Chengye Yang , Qiyuan Lu , Ying Liu , Fengyu Miao , Shimeng Ling , Zhuoran Xie
<div><div>The Buzhu gold (antimony) deposit, located within the gold-antimony polymetallic belt of southern Tibet in the Tethys Himalayan belt, is a recently discovered medium-sized gold polymetallic deposit. The orebody consists primarily of gold-bearing quartz sulfide veins. Currently, the metallogenic mechanism of the deposit remains largely unexplored. Utilizing results from the mineralogical observation of principal ore minerals, LA-ICP-MS trace element analysis, and in-situ sulfur isotope analysis of pyrite, investigations reconstruct the evolution process of pyrite-arsenopyrite and constrain the metallogenic process of the Buzhu gold (antimony) deposit. It has been discovered that the gold-bearing sulfides in the Buzhu gold (antimony) deposit are primarily pyrite and arsenopyrite. Pyrite can be categorized into six generations: framboidal pyrite Py0, dissolution cavity pyrite Py1a (some exhibiting oscillatory zoning), disseminated pyrite Py1b, euhedral pyrite Py2a, irregular pyrite Py2b, and Py3. Arsenopyrite, on the other hand, can be classified into three generations: early arsenopyrite Apy0, disseminated arsenopyrite Apy1, and euhedral Apy2. The analysis of δ<sup>34</sup>S in pyrite throughout the ore-forming process indicates sulfur derives from multiple sources, with Py0 indicative of a biological sulfur source. The evolutionary process of pyrite, supported by trace element analysis, suggests that the remaining pyrite derives from sedimentary fluid transformation, with sulfur primarily sourced from metamorphic sediments. Elemental spectrum analysis and BSE observations indicate that the Buzhu gold (antimony) deposit primarily undergoes two distinct stages of mineralization: the initial stage is the gold-antimony mineralization phase, during which antimony precipitates in the fissures of Py1a as stibnite, while gold is primarily found in Py1-Apy1 as invisible gold, with the highest gold content in Apy1 (28.20–60.13 ppm, average 40.51 ppm). The subsequent stage of mineralization is characterized by gold mineralization, with gold primarily residing in the internal fissures of Apy2 as micron silver gold ore. The evolution characteristics of gold-bearing sulphide and the solubility curve of Au indicate that gold mainly derives from gold-bearing unsaturated fluid, rather than from early framboidal pyrite Py0 (0.52–1.06 ppm, average 0.79 ppm). Only a minor fraction of gold (originating from early sediments) in Py0 was liberated and integrated into subsequent pyrites. The content of antimony in Py0 significantly reduces after dissolution, suggesting that antimony predominantly originates from Py0 (206–440 ppm, average 335 ppm). Throughout the genesis of the Buzhu gold (antimony) deposit, the gold constituent underwent a sequence of pre-enrichment, re-enrichment, liberation, and precipitation. The processes of coupled dissolution-reprecipitation (CDR) and boiling fostered the reactivation and reenrichment of gold. The recrystallization into cu
{"title":"In-situ trace element and sulfur isotope compositions of Multi-Stage sulfides in the Buzhu orogenic gold (Antimony) Deposit, southern Tibet: Implications for the metallogenic process","authors":"Xiaobin Xu , Xiaoming Sun , Zhengpeng Ding , Chengye Yang , Qiyuan Lu , Ying Liu , Fengyu Miao , Shimeng Ling , Zhuoran Xie","doi":"10.1016/j.oregeorev.2024.106323","DOIUrl":"10.1016/j.oregeorev.2024.106323","url":null,"abstract":"<div><div>The Buzhu gold (antimony) deposit, located within the gold-antimony polymetallic belt of southern Tibet in the Tethys Himalayan belt, is a recently discovered medium-sized gold polymetallic deposit. The orebody consists primarily of gold-bearing quartz sulfide veins. Currently, the metallogenic mechanism of the deposit remains largely unexplored. Utilizing results from the mineralogical observation of principal ore minerals, LA-ICP-MS trace element analysis, and in-situ sulfur isotope analysis of pyrite, investigations reconstruct the evolution process of pyrite-arsenopyrite and constrain the metallogenic process of the Buzhu gold (antimony) deposit. It has been discovered that the gold-bearing sulfides in the Buzhu gold (antimony) deposit are primarily pyrite and arsenopyrite. Pyrite can be categorized into six generations: framboidal pyrite Py0, dissolution cavity pyrite Py1a (some exhibiting oscillatory zoning), disseminated pyrite Py1b, euhedral pyrite Py2a, irregular pyrite Py2b, and Py3. Arsenopyrite, on the other hand, can be classified into three generations: early arsenopyrite Apy0, disseminated arsenopyrite Apy1, and euhedral Apy2. The analysis of δ<sup>34</sup>S in pyrite throughout the ore-forming process indicates sulfur derives from multiple sources, with Py0 indicative of a biological sulfur source. The evolutionary process of pyrite, supported by trace element analysis, suggests that the remaining pyrite derives from sedimentary fluid transformation, with sulfur primarily sourced from metamorphic sediments. Elemental spectrum analysis and BSE observations indicate that the Buzhu gold (antimony) deposit primarily undergoes two distinct stages of mineralization: the initial stage is the gold-antimony mineralization phase, during which antimony precipitates in the fissures of Py1a as stibnite, while gold is primarily found in Py1-Apy1 as invisible gold, with the highest gold content in Apy1 (28.20–60.13 ppm, average 40.51 ppm). The subsequent stage of mineralization is characterized by gold mineralization, with gold primarily residing in the internal fissures of Apy2 as micron silver gold ore. The evolution characteristics of gold-bearing sulphide and the solubility curve of Au indicate that gold mainly derives from gold-bearing unsaturated fluid, rather than from early framboidal pyrite Py0 (0.52–1.06 ppm, average 0.79 ppm). Only a minor fraction of gold (originating from early sediments) in Py0 was liberated and integrated into subsequent pyrites. The content of antimony in Py0 significantly reduces after dissolution, suggesting that antimony predominantly originates from Py0 (206–440 ppm, average 335 ppm). Throughout the genesis of the Buzhu gold (antimony) deposit, the gold constituent underwent a sequence of pre-enrichment, re-enrichment, liberation, and precipitation. The processes of coupled dissolution-reprecipitation (CDR) and boiling fostered the reactivation and reenrichment of gold. The recrystallization into cu","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106323"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106302
Xuan Wang , Yongfei Tian , Jingwen Mao , Wei Jian , Changqing Zhang , Peng Wang , Junzeng Zuo , Wenhao Tang , Zhenxu Liu , Jiayi Wu , Zhanguo Zhang
Breccia-hosted Au deposits within the North China Craton (NCC) exhibit a complex genesis, with some breccias being genetically linked to Au mineralization and others unrelated. Understanding the origin of these breccias is crucial for elucidating the genesis of associated ore deposits and guiding exploration strategies. The Haopinggou deposit in the Xiong’ershan district, on the southern margin of the NCC, comprises quartz-carbonate vein-hosted Ag–Pb–Zn–Au deposits and related breccia pipe in metamorphic rocks of the late Archean to early Paleoproterozoic Taihua Group. The origin of the Haopinggou breccia is crucial to understand the Xiayu Ag-Pb-Zn-Au mineralization (5640 t Ag). In this study, we examine the genetic relationship between breccia and Ag‒Pb‒Zn‒Au mineralization, drawing on new insights from the characteristics of the Haopinggou deposit, breccia features, breccia‒hosted Au mineralization, and isotopic data. These findings enhance our understanding of the Haopinggou Ag‒Pb‒Zn‒Au hydrothermal systems and refine exploration models for discordant breccia pipes. Recent underground tunnel surveys and drill-core logging reveal a close spatial link between the breccia and hidden granite porphyry. Juvenile magmatic clasts (granite porphyry) and cement (K-feldspar and quartz crystallized from granite porphyry) are present in the breccia pipe above a granite porphyry apophysis, indicating that the breccia was formed by phreatomagmatic brecciation caused by emplacement of the granite porphyry. Fluidization at the cm- to 100-m-scale reveals that the movement direction of clasts inside the breccia pipe was from northwest to southeast after crypto-explosion, creating a northwest-trending breccia zone. Anhedral monazite (131.2 ± 7.6 Ma) encapsulated in pyrite from the breccia constrains the upper limit of brecciation. The δ34S values of pyrite in rock flour and hydrothermal cements range from 3.8 ‰ to 5.3 ‰ (mean: 4.8 ‰) and 2.7 ‰ to 7.5 ‰ (mean: 5.2 ‰), respectively, with δ34S-sphalerite in hydrothermal cement ranging from 5.7 ‰ to 6.1 ‰ (mean: 5.9 ‰) and δ34S-chalcopyrite ranging from − 0.9 ‰ to 5.6 ‰ (mean: 2.9 ‰). The S isotope characteristics of vein-hosted and breccia-hosted mineralization zones are consistent, with complete alignment of the sulfide assemblages and alteration features. These pieces of evidence collectively indicate that both vein- and breccia-hosted mineralization zones are products of magmatic activity. The metallogenic model for the Haopinggou breccia pipe underscores its unique formation mechanism, driven by pre-existing northwest-striking structural weaknesses and fluidization. This model implies a predominant northwest‒to‒southeast transport of clasts and raises the hypothesis of an underlying porphyry‒type Au mineralization system at depth.
华北克拉通（NCC）内的角砾岩赋存金矿床显示出复杂的成因，一些角砾岩与金矿化在成因上有关联，而另一些则没有关联。了解这些角砾岩的成因对于阐明伴生矿床的成因和指导勘探战略至关重要。熊耳山地区的下坪沟矿床位于新中国成立后的南缘，由石英碳酸盐岩脉型银铅锌金矿床和相关的角砾岩管组成，赋存于晚阿尔川世至早古生代太华组的变质岩中。下坪沟角砾岩的成因对于了解下峪银-铅-锌-金矿化（5640 吨银）至关重要。 在本研究中，我们从下坪沟矿床的特征、角砾岩特征、角砾岩赋存的金矿化以及同位素数据中汲取了新的见解，研究了角砾岩与银铅锌金矿化之间的遗传关系。这些发现加深了我们对下坪沟银铅锌金热液系统的了解，并完善了不和谐角砾岩管道的勘探模型。最近的地下隧道勘测和钻探岩芯测井揭示了角砾岩与隐伏花岗斑岩之间的密切空间联系。在花岗斑岩apophysis上方的角砾岩管中存在幼年岩浆碎屑（花岗斑岩）和胶结物（花岗斑岩中结晶的钾长石和石英），表明角砾岩是由花岗斑岩成岩引起的相岩浆角砾岩化形成的。厘米至 100 米尺度的流体化显示，在隐爆之后，角砾岩管内部的碎屑移动方向是西北至东南，形成了一个西北走向的角砾岩带。角砾岩中黄铁矿包裹的正方体独居石（131.2 ± 7.6 Ma）限制了角砾岩化的上限。岩粉和热液胶结物中黄铁矿的δ34S值分别为3.8‰至5.3‰（平均值：4.8‰）和2.7‰至7.5‰（平均值：5.2‰），热液胶结物中的δ34S-闪锌矿的范围分别为5.7‰至6.1‰（平均值：5.9‰），δ34S-黄铜矿的范围为-0.9‰至5.6‰（平均值：2.9‰）。脉托成矿带和角砾岩托成矿带的 S 同位素特征是一致的，硫化物组合和蚀变特征完全一致。这些证据共同表明，岩脉和角砾岩矿化带都是岩浆活动的产物。下坪沟角砾岩管的成矿模式强调了其独特的形成机制，即由先前存在的西北走向构造薄弱环节和流化作用所驱动。这一模型意味着碎屑主要是由西北向东南方向运移，并提出了深部潜在斑岩型金矿化系统的假设。
{"title":"Genesis of the Haopinggou breccia-hosted Au deposit, western Henan Province, China","authors":"Xuan Wang , Yongfei Tian , Jingwen Mao , Wei Jian , Changqing Zhang , Peng Wang , Junzeng Zuo , Wenhao Tang , Zhenxu Liu , Jiayi Wu , Zhanguo Zhang","doi":"10.1016/j.oregeorev.2024.106302","DOIUrl":"10.1016/j.oregeorev.2024.106302","url":null,"abstract":"<div><div>Breccia-hosted Au deposits within the North China Craton (NCC) exhibit a complex genesis, with some breccias being genetically linked to Au mineralization and others unrelated. Understanding the origin of these breccias is crucial for elucidating the genesis of associated ore deposits and guiding exploration strategies. The Haopinggou deposit in the Xiong’ershan district, on the southern margin of the NCC, comprises quartz-carbonate vein-hosted Ag–Pb–Zn–Au deposits and related breccia pipe in metamorphic rocks of the late Archean to early Paleoproterozoic Taihua Group. The origin of the Haopinggou breccia is crucial to understand the Xiayu Ag-Pb-Zn-Au mineralization (5640 t Ag). In this study, we examine the genetic relationship between breccia and Ag‒Pb‒Zn‒Au mineralization, drawing on new insights from the characteristics of the Haopinggou deposit, breccia features, breccia‒hosted Au mineralization, and isotopic data. These findings enhance our understanding of the Haopinggou Ag‒Pb‒Zn‒Au hydrothermal systems and refine exploration models for discordant breccia pipes. Recent underground tunnel surveys and drill-core logging reveal a close spatial link between the breccia and hidden granite porphyry. Juvenile magmatic clasts (granite porphyry) and cement (K-feldspar and quartz crystallized from granite porphyry) are present in the breccia pipe above a granite porphyry apophysis, indicating that the breccia was formed by phreatomagmatic brecciation caused by emplacement of the granite porphyry. Fluidization at the cm- to 100-m-scale reveals that the movement direction of clasts inside the breccia pipe was from northwest to southeast after crypto-explosion, creating a northwest-trending breccia zone. Anhedral monazite (131.2 ± 7.6 Ma) encapsulated in pyrite from the breccia constrains the upper limit of brecciation. The δ<sup>34</sup>S values of pyrite in rock flour and hydrothermal cements range from 3.8 ‰ to 5.3 ‰ (mean: 4.8 ‰) and 2.7 ‰ to 7.5 ‰ (mean: 5.2 ‰), respectively, with δ<sup>34</sup>S-sphalerite in hydrothermal cement ranging from 5.7 ‰ to 6.1 ‰ (mean: 5.9 ‰) and δ<sup>34</sup>S-chalcopyrite ranging from − 0.9 ‰ to 5.6 ‰ (mean: 2.9 ‰). The S isotope characteristics of vein-hosted and breccia-hosted mineralization zones are consistent, with complete alignment of the sulfide assemblages and alteration features. These pieces of evidence collectively indicate that both vein- and breccia-hosted mineralization zones are products of magmatic activity. The metallogenic model for the Haopinggou breccia pipe underscores its unique formation mechanism, driven by pre-existing northwest-striking structural weaknesses and fluidization. This model implies a predominant northwest‒to‒southeast transport of clasts and raises the hypothesis of an underlying porphyry‒type Au mineralization system at depth.</div></div>","PeriodicalId":19644,"journal":{"name":"Ore Geology Reviews","volume":"174 ","pages":"Article 106302"},"PeriodicalIF":3.2,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586146","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}
Porphyry copper systems contain porphyry Cu, skarn, carbonate-replacement and epithermal deposits, and presently supply nearly all the Te and Se, and have the potential to produce Co as by-product in the future. However, few studies have investigated the distribution of Co, Te, and Se in the specific porphyry-skarn deposit. Detailed mineralogical and geochemical analyses were conducted to investigate the distribution of Co, Te, and Se across porphyry, skarn, and carbonate-replacement ore types in the Tonglvshan porphyry-skarn Cu-Fe-Au deposit, Eastern China. The early sulfide stage in three ore types is characterized by Co-bearing pyrite (Py1a, Co up to 1.3 wt%) + droplet-like tetradymite ± hessite ± cattierite. The texture transition from coarse-grained, pore-free to porous Py1a in porphyry and skarn type ores suggests a shift from stable physico-chemical conditions to gentle fluid boiling, resulting in the precipitation of Co- and Te-bearing minerals. In contrast, fine-grained euhedral Py1a in carbonate-replacement type ores implies rapid cooling from high-temperature fluid interaction with marble.
The late sulfide stage, which only occurs in skarn and carbonate-replacement type ores, is characterized by Co-rich pyrite (Py2) + carrollite + hessite + Bi-sulfosalts. In skarn type ores, tetradymite-kawazulite solid solution (TKSS) + hessite + native Te + naumannite reflects intense boiling, leading to an increase in fO2 and pH that precipitates Py2b (Co up to 19.2 wt%) and carrollite, while Te and Se may precipitate through vapor phase condensation. Conversely, the presence of fine-grained carrollite, zoned Py2a, sphalerite, and galena in carbonate-replacement type ore suggests that rapid cooling and increasing pH, resulting from fluid mixing, played a significant role in the precipitation Co and Te. Furthermore, the porous texture resulting from coupled dissolution-reprecipitation (CDR) during the late sulfide stage also provided favorable conditions for the formation of micro-nano sized critical metal particles.
斑岩铜系统包括斑岩铜、矽卡岩、碳酸盐置换和热液矿床，目前几乎提供所有的碲和硒，并有可能在未来生产副产品钴。然而，很少有研究调查特定斑岩-矽卡岩矿床中钴、碲和硒的分布情况。为了研究中国东部铜绿山斑岩-矽卡岩铜-铁-金矿床中钴、碲和硒在斑岩、矽卡岩和碳酸盐置换矿石类型中的分布，我们进行了详细的矿物学和地球化学分析。三种矿石类型的早期硫化物阶段的特征是含钴黄铁矿（Py1a，钴含量高达 1.3 wt%）+水滴状四铁矿±辉绿岩±猫铁矿。斑岩型和矽卡岩型矿石中从粗粒、无孔到多孔 Py1a 的质地转变表明，从稳定的物理化学条件转变为温和的流体沸腾，导致含 Co 和 Te 的矿物沉淀。与此相反，碳酸盐置换型矿石中的细粒八面体Py1a意味着高温流体与大理岩相互作用后的快速冷却。晚期硫化物阶段仅出现在矽卡岩型和碳酸盐置换型矿石中，其特征是富钴黄铁矿（Py2）+卡罗来石+辉锑矿+双硫化物。在矽卡岩型矿石中，四闪长岩-卡瓦祖利石固溶体（TKSS）+红柱石+原生碲+瑙锰矿反映出强烈的沸腾，导致 fO2 和 pH 值升高，从而沉淀出 Py2b（钴含量高达 19.2 wt%）和卡罗莱石，而碲和硒则可能通过气相凝结沉淀出来。相反，碳酸盐置换型矿石中存在细粒榴辉岩、带状Py2a、闪锌矿和方铅矿，这表明流体混合导致的快速冷却和pH值升高在Co和Te的沉淀中起了重要作用。此外，硫化物晚期阶段的溶解-再沉淀耦合作用（CDR）所产生的多孔质地也为微纳尺寸临界金属颗粒的形成提供了有利条件。
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Pub Date : 2024-11-01DOI: 10.1016/j.oregeorev.2024.106330
Ahmad Rabiee , Federico Rossetti , Michele Lustrino , Hossein Azizi , Yoshihiro Asahara , Saeed Alipour , David Selby
This study investigates the temporal relationships between mineralization and magmatism in the Khatoon-Abad porphyry Mo-Cu prospect (Urumieh-Dokhtar Magmatic Arc, NW Iran). Integrated zircon U-Pb and molybdenite Re-Os dating document a prolonged stationary magmatism, spanning ∼ 45 Myr (from ∼ 66 to ∼ 21 Ma; Paleocene-Early Miocene). Three main Oligocene ore-bearing granitic intrusions and an early Miocene barren dyke swarm are documented, with the main mineralization formed at ∼ 27 Ma, as attested by the molybdenite Re-Os age of 26.75 ± 0.14 Ma and the zircon U-Pb age 26.93 ± 0.30 Ma from the host granodiorite porphyry. Despite having similar geochemical fingerprints, including an adakitic signature and having REE patterns similar to productive magmas, the subsequent Oligocene granite bodies (∼26.0–25.7 Ma) yielded lower Mo-Cu enrichments and the early Miocene rhyodacite dykes (∼21 Ma) are barren. This evidence demonstrates that the efficiency of mineralization has been reduced by changes in the physiochemical conditions of magmatic-hydrothermal systems over time. We suggest that a perturbed geothermal gradient during later Oligocene granite (at ∼ 26 Ma) caused slow cooling/degassing of the melts, and hence determined an inefficient mineralization environment. We also infer that during the latest granite porphyry pulse (∼25.7 Ma), the structurally-controlled emplacement at shallower levels resulted in rapid melt cooling along with more meteoric water mixing, eventually minor potassic but vast phyllic alterations, and hence, causing a dispersed mineralization rather than a focused fluid flow. Therefore, the later Oligocene and early Miocene magmatic pulses degraded the early mineralization. The results of this study emphasize that a consistent magma supply into the chamber followed by a rapid magma-fluid flux to the mineralization site are needed for efficient mineralization in collisional settings. Otherwise, multiple mineralization pathways and sites would result in low-grade ore bodies.
本研究调查了 Khatoon-Abad 斑岩钼铜矿探矿区（伊朗西北部乌鲁米耶-多赫塔尔岩浆弧）矿化与岩浆活动之间的时间关系。综合锆石 U-Pb 和辉钼矿 Re-Os 测定记录了一个漫长的静止岩浆活动，时间跨度达 45 Myr（从 66 Ma 到 21 Ma；古新世-早中新世）。记录了三个主要的渐新世含矿花岗岩侵入体和一个早中新世贫瘠堤群，主要矿化形成于 ∼ 27 Ma，这可以从主控花岗闪长岩斑岩的辉钼矿 Re-Os 年龄 26.75 ± 0.14 Ma 和锆石 U-Pb 年龄 26.93 ± 0.30 Ma 得到证明。尽管具有类似的地球化学特征，包括阿达克特特征，并具有与高产岩浆相似的 REE 模式，但随后的渐新世花岗岩体（∼26.0-25.7 Ma）的 Mo-Cu 富集度较低，而早中新世流纹岩堤（∼21 Ma）则贫瘠。这些证据表明，随着时间的推移，岩浆-热液系统理化条件的变化降低了成矿效率。我们认为，在晚渐新世花岗岩时期（26 Ma ∼），地热梯度的扰动导致熔体冷却/脱气缓慢，从而决定了成矿环境的低效率。我们还推断，在最近一次花岗斑岩脉冲期间（25.7Ma∼），结构控制下的较浅层位赋存导致熔体快速冷却，同时更多的陨石水混合，最终产生了轻微的钾质变化，但却产生了巨大的植物变化，因此造成了分散的成矿作用，而不是集中的流体流动。因此，渐新世晚期和中新世早期的岩浆脉冲使早期矿化退化。这项研究的结果强调，在碰撞环境中，需要有持续的岩浆供应进入腔室，然后岩浆流体快速流向成矿部位，才能实现高效成矿。否则，多种成矿途径和地点将导致低品位矿体。
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