Resource Geology最新文献

{"title":"Geological, mineralogical, and oxygen isotope studies of the Chandmani Uul iron oxide–copper–gold deposit in Dornogobi Province, Southeastern Mongolia","authors":"Luvsannyam Oyunjargal, K. Hayashi, T. Maruoka","doi":"10.1111/rge.12232","DOIUrl":"https://doi.org/10.1111/rge.12232","url":null,"abstract":"The Chandmani Uul deposit is located in Dornogovi province, Southeastern Mongolia. Iron oxide ores are hosted in the andesitic rocks of the Shar Zeeg Formation of Neoproterozoic to Lower‐Cambrian age. Middle‐ to Upper‐Cambrian bodies of granitic rocks have intruded into the host rocks in the western and southern regions of the deposit. The wall rocks around the iron oxide ore bodies were hydrothermally altered to form potassic, epidote, and sericite–chlorite alteration zones, and calcite and quartz veinlets are ubiquitous in the late stage. Since granitic rocks also underwent potassic alteration, the activity of the granitic rocks must have a genetic relation to the ore deposit. The ore mineral assemblage is dominated by iron oxides such as mushketovite, euhedral magnetite with concentric and/or oscillatory zoning textures, and cauliflower magnetite. Lesser amounts of chalcopyrite and pyrite accompany the iron oxides. Among all these products, mushketovite is dominant and is distributed throughout the deposit. Meanwhile, euhedral magnetite appears in limited amounts at relatively shallow levels in the deposit. By contrast, cauliflower magnetite appears locally in the deeper parts of the deposit, and is associated with green‐colored garnet and calcite. Sulfide minerals are ubiquitously associated with these iron oxides. The oxygen isotope (δ18O) values of all types of magnetite, quartz, and epidote were found to be −5.9 to −2.8‰, 10.5 to 14.9‰, and 3.6 to 6.6‰, respectively. The δ18O values of quartz–magnetite pairs suggest an equilibrium isotopic temperature near 300°C. The calculated values of δ18O for the water responsible for magnetite ranged from 2 to 10‰. All the data obtained in this study suggest that the iron oxide deposit at the Chandmani Uul is a typical iron oxide–copper–gold deposit, and that this deposit was formed at an intermediate depth with potassic and sericite–chlorite alteration zones under the oxidized conditions of a hematite‐stable environment. The δ18O range estimated implies that the ore‐forming fluid was supplied by a crystallizing granodioritic magma exsolving fluids at depth with a significant contribution of meteoric water.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90712154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical characteristics of ores and surface waters for environmental risk assessment in the Pinpet iron deposit, southern Shan State, Myanmar","authors":"Kyaw Zay Ya, T. Otake, A. Koide, K. Sanematsu, Tsutomu Sato","doi":"10.1111/rge.12231","DOIUrl":"https://doi.org/10.1111/rge.12231","url":null,"abstract":"Mining operations in the Pinpet Fe deposit, which is the second‐largest Fe deposit in Myanmar, are currently suspended, in part because of possible contamination of heavy metals and hazardous elements (e.g., Fe, As, Cu, Zn, and U) into the surrounding aquatic environment and associated public concern. However, a scientific investigation of the source and degree of contamination in streams near the deposit has not yet been conducted. Therefore, we quantified heavy‐metal and hazardous‐element concentrations of stream waters and sediments in stream beds, and measured the speciation and concentration of these metals in deposit Fe ores using the sequential extraction method, to better understand the influence of mining activities on the surrounding environment. Geochemical results for Nan‐tank‐pauk stream and its tributaries indicate that the chemical compositions of their waters are controlled by carbonate bedrock and that no detectable contamination has occurred as a result of mining activity or hematite and limonite ore beneficiation processes in either the wet or dry seasons. All measured heavy‐metal and hazardous‐element concentrations were below the World Health Organization standards for drinking water and the proposed national drinking water quality standards in Myanmar. Bulk chemical compositions of stream‐bed and tailings dam sediments show that As, Zn, and Cu concentrations are similar to those in uncontaminated sediments. Results of bulk mineralogical and chemical analyses of ore samples reveal that some limonite ore samples contain substantial amounts of As (up to 2 wt%). However, sequential extraction results indicate that most (>90%) of the As in these As‐rich ores is hosted in insoluble fractions (e.g., crystalline Fe hydroxides and clays). Therefore, arsenic is unlikely to be released into the aquatic environment by interacting with water during ore beneficiation processes should the mine resume operations.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81657351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study of igneous rocks related to Zn–Pb mineralization in the Shinyemi and Gagok deposits of the Taebaeksan Basin, South Korea","authors":"Jieun Seo, S. Choi, Min-Ho Koo, C. Oh, In-Chang Ryu, G. Lee","doi":"10.1111/rge.12230","DOIUrl":"https://doi.org/10.1111/rge.12230","url":null,"abstract":"The Shinyemi and Gagok deposits, located in the Taebaeksan Basin, South Korea, display Zn–Pb mineralization along a contact between Cretaceous granitoids and Cambrian–Ordovician carbonates of the Joseon Supergroup. The Shinyemi mine is one of the largest polymetallic skarn‐type magnetite deposits in South Korea and comprises Fe and Fe–Mo–Zn skarns, and Zn–Cu–Pb replacement deposits. Both deposits yield similar Cretaceous mineralization ages, and granitoids associated with the two deposits displaying similar mineral textures and compositions, are highly evolved, and were emplaced at a shallow depth. They are classified as calc‐alkaline, I‐type granites (magnetite series) and were formed in a volcanic arc. Compositional variation is less in the Shinyemi granites and aplites (e.g., SiO2 = 74.4–76.6 wt% and 74.4–75.1 wt%, respectively) than in the Gagok granites and aplites (e.g., SiO2 = 65.6–68.0 wt% and 74.9–76.5 wt%, respectively). Furthermore, SiO2 vs K/Rb and SiO2 vs Rb/Sr diagrams indicate that the Shinyemi granitoids are more evolved than the Gagok granitoids. Shinyemi granitoids had been already differentiated highly in deep depth and then intruded into shallow depth, so both granite and aplite show the highly evolved similar chemical compositions. Whereas, less differentiated Gagok granitoids were separated into two phases in the last stage at shallow depth, so granite and aplite show different compositions. The amounts of granites and aplite are similar in the Shinyemi deposit, whereas the aplite appears in an amount less than the granite in the Gagok deposit. For this reason, the Shinyemi granitoids caused not only Fe enrichment during formation of the dolomite‐hosted magnesian skarn but also was associated with Mo mineralization in the Shinyemi deposit. Zn mineralization of the Gagok deposit was mainly caused by granite rather than aplite. Our data suggest that the variation in mineralization displayed by the two deposits resulted from differences in the compositions of their associated igneous intrusions.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84426318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The relationship between hydrocarbon accumulation and Mississippi Valley‐type Pb‐Zn mineralization of the Mayuan metallogenic belt, the northern Yangtze block, SW China: Evidence from ore geology and Rb‐Sr isotopic dating","authors":"Guozhi Wang, Zhu Huang, Fufeng Zhao, Na Li, Yuzhen Fu","doi":"10.1111/rge.12229","DOIUrl":"https://doi.org/10.1111/rge.12229","url":null,"abstract":"The coexistence of Pb‐Zn deposits and oil/gas reservoirs demonstrates that a close genetic connection exists between them. The spatiotemporal relationship between Pb‐Zn mineralization and hydrocarbon accumulation is the key to understanding this genetic connection. The Mayuan large‐scale Pb‐Zn metallogenic belt is composed of a number of Mississippi Valley‐type (MVT) Pb‐Zn deposits that were recently discovered on the northern margin of the Yangtze Block, China. It is hosted in the dolostone of the Sinian (Ediacaran) Dengying Formation (Z2dn). In addition to the abundant bitumen in the Mayuan Pb‐Zn metallogenic belt, the paleo‐oil reservoir and the MVT Pb‐Zn deposit overlap in space. In this study, two precise ages of 468.3 ± 3.8 Ma and 206.0 ± 6.5 Ma were obtained via the Rb‐Sr isotopic dating of galena and sphalerite from the Mayuan Pb‐Zn metallogenic belt, respectively. The early metallogenic age of 468.3 ± 3.8 Ma is similar to the previously published age of 486 ± 12 Ma. The age of 206.0 ± 6.5 Ma is consistent with the age of the metallogenic event that occurred at 200 Ma in the Upper Yangtze Pb–Zn metallogenic province of the Sichuan‐Yunnan‐Guizhou polymetallic zone, which is located on the southwest margin of the Sichuan Basin, suggesting that the metallogenic effects of this period were regional in scale in the peripheral areas of the Sichuan Basin. Previous studies have shown that two periods of hydrocarbon accumulation occurred in the oil/gas reservoir that coexists with the Pb‐Zn deposits in the study area. The Pb‐Zn mineralization at 468.3 ± 3.8 Ma occurred during the first period of hydrocarbon accumulation, while the second mineralization at 206.0 ± 6.5 Ma occurred during the transformation of the paleo‐oil reservoir to a paleogas reservoir. The spatial relationship between the paleo‐oil/‐gas reservoir and the MVT Pb‐Zn deposits and the temporal relationship between mineralization and hydrocarbon accumulation show that a close genetic relationship exists between the MVT Pb‐Zn mineralization and hydrocarbon accumulation. Analysis of metals in the source rocks forming the paleo‐oil/‐gas reservoirs show that source rocks which formed paleo‐oil/‐gas reservoirs may have provided metals for Pb‐Zn mineralization. Both the paleo‐oil/‐gas reservoirs and Pb‐Zn mineralizing fluids had the same origin.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74023836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Titanium‐in‐biotite thermometry in porphyry copper systems: Challenges to application of the thermometer","authors":"M. Rezaei, A. Zarasvandi","doi":"10.1111/rge.12227","DOIUrl":"https://doi.org/10.1111/rge.12227","url":null,"abstract":"Empirical geothermometer dealing with Ti solubility in the Fe‐Mg biotites was originally proposed for biotites in graphitic, peraluminous metapelites containing ilmenite or rutile that equilibrated roughly at 4–6 kbar. Given that biotites are abundant in the porphyry copper systems, this geothermometer has frequently been used for the determination of magmatic–hydrothermal temperatures in the porphyry copper systems. Common associations of porphyry copper deposits (PCDs), that is, low Al content of biotite, biotite chloritization (causes the biotite to become more magnesian and to lose Ti), and biotite formation by amphibole replacement, as well as disequilibrium, local equilibrium, or re‐equilibration of biotites, especially through potassic alteration, may provide significant uncertainty in the temperatures estimated a by Ti‐in‐biotite geothermometer. In addition, besides the calibration range of thermometer for pressure (400–600 MPa), the temperatures of major sulfide precipitation in PCDs (>~400°C) does not fit with the temperature range of thermometer calibration (480–800°C). Worth noting, as confirmed by fluid inclusion data in the Sarkuh PCD, regardless of presence of mineralogical requirements, obtained temperatures of sulfide mineralization using Ti in biotite thermometer could be overestimated. This may be due to the difference between general conditions of sulfide mineralization and calibration range of Ti in the biotite thermometer for pressure and temperature, as well as the metaluminous nature of biotites in PCDs.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82142709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochronology and fluid source constraints of the Songligou gold‐telluride deposit, western Henan Province, China: Analysis of genetic implications","authors":"Peng-liang Wang, Wei Jian, J. Mao, Huishou Ye, Weiwei Chao, Yongfei Tian, Jianming Yan","doi":"10.1111/rge.12228","DOIUrl":"https://doi.org/10.1111/rge.12228","url":null,"abstract":"The Songligou gold‐telluride deposit, located in Songxian County, western Henan Province, China, is one of many gold‐telluride deposits in the Xiaoqinling‐Xiong'ershan district. Gold orebodies occur within the Taihua Supergroup and are controlled by the WNW F101 Fault, and the fault was cut across by a granite porphyry dike. Common minerals in gold orebodies include quartz, chlorite, epidote, K‐feldspar, calcite, fluorite, sericite, phlogopite, bastnasite, pyrite, galena, chalcopyrite, sphalerite, tellurides, gold, bismuthinite, magnetite, and hematite, and pyrite is the dominant sulfide. Four mineralization stages are recognized, including pyrite‐quartz stage (I), quartz‐pyrite stage (II), gold‐telluride stage (III), and quartz‐calcite stage (IV). This work reports the Rb–Sr age of gold‐telluride‐bearing pyrite and zircon U–Pb age of granite porphyry, as well as S isotope data of pyrite and galena. The pyrite Rb–Sr isochron age is 126.6 ± 2.3 Ma (MSWD = 1.8), and the average zircon U–Pb age of granite porphyry is 166.8 ± 4.1 Ma (MSWD = 4.9). (87Sr/86Sr) i values of pyrite and δ34S values of sulfides vary from 0.7104 to 0.7105 and −11.84 to 0.28‰, respectively. The obtained Rb–Sr isochron age represents the ore formation age of the Songligou gold‐telluride deposit, which is much younger than the zircon U–Pb age of the granite porphyry. Strontium and S isotopes, together with the presence of bastnaesite, suggest that the ore‐forming fluid was derived from felsic magmas with input of a mantle component and subsequently interacted with the Taihua Supergroup. Tellurium was derived from metasomatized mantle and was related to the subduction of the Shangdan oceanic crust and Izanagi plate beneath the North China Craton (NCC). This deposit is a part of the Early Cretaceous large‐scale gold mineralization in east NCC and formed in an extensional tectonic setting.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88369043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"U–Pb geochronology and Raman spectroscopy of zircons from the granites in the Xihuashan and Tieshanlong Deposit: Implications for W‐Sn mineralization in Southern Jiangxi Province, South China","authors":"Xiaofei Guo, Kaixing Wu, Yu Tian, Xiao-Bing Zhang","doi":"10.1111/rge.12226","DOIUrl":"https://doi.org/10.1111/rge.12226","url":null,"abstract":"The Xihuashan and Tieshanlong tungsten deposit is an important large quartz vein‐type W‐polymetallic deposit in the southern Jiangxi Province, eastern Nanling Range. Zircon U–Pb analyses of representative ore‐forming granites from the Xihuashan and Tieshanlong tungsten deposit yield ages of 146.3 ± 2.9 Ma and 146.0 ± 3.8 Ma, respectively. According to the zircon Raman spectroscopy, these granitic rocks are disturbed by different degrees of hydrothermal alteration, whereas most zircons exhibit primary oscillatory zoning and Th/U ratios in the range of magmatic zircon, which means the analysis results represent the crystallization age of metallogenetic granitic assemblages. In combination with regional geological data, it is suggested that the Late Jurassic is probably another important episode of granitic magmatism and W‐Sn mineralization in southern Jiangxi Provinces, even South China.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81807255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geological and Geophysical Studies of Sulfide Copper Mineralization in the Dochileh Area: An Example of Manto‐Type Deposit in the Sabzevar Zone, Iran","authors":"Susan Ebrahimi, A. Arab-Amiri, A. Kamkar-Rouhani","doi":"10.1111/rge.12222","DOIUrl":"https://doi.org/10.1111/rge.12222","url":null,"abstract":"The Dochileh stratiform copper deposit in the Sabzevar Zone of northeastern Iran is hosted in the basaltic sequence of the Upper Eocene age. The host rock displays two hydrothermal events: zeolite–carbonate alteration that is a stratigraphic–lithologic feature and chlorite and chlorite/ferruginous alterations in the local mineralized structures. Ore formation is related to both hydrothermal events and occurs in both stratiform and vein mineralization types. Mineralization consists of main chalcocite with variable amounts of bornite, chalcopyrite, native copper, malachite, and cuprite minerals, which occur as hydrothermal breccias, and disseminated, vein, and veinlet forms. Geophysical field studies using resistivity and induction polarization (IP) methods were conducted along nine survey lines in the area. As a result of modeling and interpretation of the acquired geophysical data, high values of IP and resistivity corresponding to mineralization were observed at two depth levels: 0–20 m and more than 40 m. Based on these geological and geophysical investigations, six locations for drilling exploration boreholes were proposed. Drilling data confirmed the mineralization containing high copper values in the two depth levels: the vein‐type mineralization in the surface and shallow depth level, and the stratiform mineralization at the deeper level. Fluid inclusion studies in calcite and quartz from stratiform‐ and vein‐type mineralization show the evidence of mixing, and a linear dilution trend during the ore formation occurred at a wide range of temperatures: 121–308°C and 80–284°C, respectively, and varying salinities of between 3.2–16.8 and 0.8–22 wt% NaCl equivalents. The stable isotope composition of δ34S that falls in a range of −2.4 to +25.0‰ could be considered biogenetic sulfur from bacterial sulfate reduction and leaching of sulfur from hosting basalt. The δ13C values of calcite vary between −0.6 and −7.6‰, suggesting a major contribution of marine carbonates associated with igneous carbonates, and the δ18OSMOW values of calcite are between +15.2 and +19.9‰, suggesting a contribution of δ18O‐rich sedimentary rocks and δ18O‐poor meteoric water. Copper and sulfide‐rich hydrothermal fluid have flowed upward through the local faults and permeable interbeds within the Eocene volcanic sequence and have formed the mineralized veins and horizons. The geophysical results have detected the local faults as the channel ways for mineralization.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90217675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic matters and acid‐sulfate alteration in Itomuka mercury mine, Hokkaido, Japan: Implications for the transportation and deposition mechanisms of Hg","authors":"T. Echigo, M. Kimata, M. Shimizu","doi":"10.1111/rge.12225","DOIUrl":"https://doi.org/10.1111/rge.12225","url":null,"abstract":"In order to examine the transportation and deposition mechanisms of Hg, we investigated the ore and hydrothermal alteration minerals and solid organic matters from Itomuka mercury mine located in the eastern part of central Hokkaido. In addition to the ore minerals, native mercury and cinnabar, quartz, marcasite, alunite, kaolinite, and minor amounts of pyrite and smectite were identified in the Hg ore by powder X‐ray diffraction (XRD) analysis. This mineral assemblage of acid sulfate alteration was likely developed under the conditions of low temperature (≤100°C) and low pH (≤2) in the steam‐heated environment. The H2SO4 was produced above the water table by the oxidation of H2S separated from deep, near‐neutral fluids by boiling. The dominance of native mercury over cinnabar in Hg ore indicates that the greater part of mineralized Hg was transported as Hg0 in aqueous solution and vapor with low sulfur fugacity. The solid organic matters found in the Hg ore were analyzed with SEM‐EDS, micro‐XRD, and micro‐Fourier transform infrared (FTIR) spectroscopy, and these results suggest that the organic matters contributed to keeping the low fO2 of the Hg‐bearing fluid and transportation of Hg as Hg0 in S‐poor condition. Because the solubility of Hg in acidic fluid is low, neutral to alkaline fluid seems to have leached Hg from the basement sedimentary rocks of Hidaka Group which also supplied the organic matters to the fluid. The oxidation and cooling of Hg‐bearing solution and vapor triggered the deposition of liquid Hg as a primary phase.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90805897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cu–Mo Differential Mineralization Mechanism of the Dabate Polymetallic Deposit in Western Tianshan, NW China: Evidence from Geology, Fluid Inclusions, and Oxygen Isotope Systematics","authors":"Rui Cao, Shengchao Yan, Bin Chen, Keke Sun, Qinglin Zhang, Haodong Gu","doi":"10.1111/rge.12218","DOIUrl":"https://doi.org/10.1111/rge.12218","url":null,"abstract":"Classic porphyry Cu–Mo deposits are mostly characterized by close temporal and spatial relationships between Cu and Mo mineralization. The northern Dabate Cu–Mo deposit is a newly discovered porphyry Cu–Mo polymetallic deposit in western Tianshan, northwest China. The Cu mineralization postdates the Mo mineralization and is located in shallower levels in the deposit, which is different from most classic porphyry Cu–Mo deposits. Detailed field investigations, together with microthermometry, laser Raman spectroscopy, and O‐isotope studies of fluid inclusions, were conducted to investigate the origin and evolution of ore‐forming fluids from the main Mo to main Cu stage of mineralization in the deposit. The results show that the ore‐forming fluids of the main Mo stage belonged to an NaCl + H2O system of medium to high temperatures (280–310°C) and low salinities (2–4 wt% NaCl equivalent (eq.)), whereas that of the main Cu stage belonged to an F‐rich NaCl + CO2 + H2O system of medium to high temperatures (230–260°C) and medium to low salinities (4–10 wt% NaCl eq.). The δ18O values of the ore‐forming fluids decrease from 3.7–7.8‰ in the main Mo stage to −7.5 to −2.9‰ in the main Cu stage. These data indicate that the separation of Cu and Mo was closely related to a large‐scale vapor–brine separation of the early ore‐forming fluids, which produced the Mo‐bearing and Cu‐bearing fluids. Subsequently, the relatively reducing (CH4‐rich) Mo‐bearing, ore‐forming fluids, dominantly of magmatic origin, caused mineralization in the rhyolite porphyry due to fluid boiling, whereas the relatively oxidizing (CO2‐rich) Cu‐bearing, ore‐forming fluids mixed with meteoric water and precipitated chalcopyrite within the crushed zone at the contact between rhyolite porphyry and wall rock. We suggest that the separation of Cu and Mo in the deposit may be attributed to differences in the chemical properties of Cu and Mo, large‐scale vapor–brine separation of early ore‐forming fluids, and changes in oxygen fugacity.","PeriodicalId":21089,"journal":{"name":"Resource Geology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2019-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72585209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}