Geology and Isotope Geochemistry of the Yinchanggou-Qiluogou Pb-Zn Deposit, Sichuan Province, Southwest China |
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| Authors: | LI Bo ZHOU Jiaxi LI Yingshu CHEN Aibing and WANG Ruixue |
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| Institution: | 1 Faculty of Land Resource Engineering, Kunming University of Science and Technology, Yunnan Kunming, 650093, China,2 State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guizhou Guiyang 550081, China,1 Faculty of Land Resource Engineering, Kunming University of Science and Technology, Yunnan Kunming, 650093, China,1 Faculty of Land Resource Engineering, Kunming University of Science and Technology, Yunnan Kunming, 650093, China and 1 Faculty of Land Resource Engineering, Kunming University of Science and Technology, Yunnan Kunming, 650093, China |
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| Abstract: | The Yinchanggou‐Qiluogou Pb‐Zn deposit, located in the western Yangtze Block, southwest China, is hosted by the Upper Sinian Dengying Formation dolostone. Ore bodies occur in the Qiluogou anticline and the NS‐ and NNW‐trending faults. Sulfide ores mainly consist of sphalerite, pyrite, galena and calcite, with subordinate dolomite and quartz. Seventeen ore bodies have been discovered to date and they have a combined 1.0 million tons of sulfide ores with average grades of 2.27wt% Zn and 6.89wt% Pb. The δDH2O‐SMOW and δ18OH2O‐SMOW values of fluid inclusions in quartz and calcite samples range from ?68.9‰ to ?48.7‰ and 7.3‰ to 15.9‰, respectively, suggesting that H2O in the hydrothermal fluids sourced from metamorphic water. Calcite samples have δ13CPDB values ranging from ?6.2‰ to ?4.1‰ and δ18OSMOW values ranging from 15.1‰ to 17.4‰, indicating C and O in the hydrothermal fluids likely derived from a mixed source of metamorphic fluids and the host carbonates. The δ34SCDT values of sulfide minerals range from 5.5‰ to 20.3‰, suggesting that thermal chemical reduction of sulfate minerals in evaporates were the most probable source of S in the hydrothermal fluids. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sulfide minerals fall in the range of 18.11 to 18.40, 15.66 to 15.76 and 38.25 to 38.88, respectively. The Pb isotopic data of the studied deposit plot near the upper crust Pb evolution curve and overlap with the age‐corrected Proterozoic basement rocks and the Upper Sinian Dengying Formation hosting dolostone. This indicates that the Pb originated from a mixed source of the basement metamorphic rocks and the ore‐hosting carbonate rocks. The ore geology and C‐H‐O‐S‐Pb isotopic data suggest that the Yinchanggou‐Qiluogou deposit is an unusual carbonate‐hosted, strata‐bound and epigenetic deposit that derived ore‐forming materials from a mixed source of the underlying Porterozoic basements and the Sinian hosting carbonates. |
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| Keywords: | C-H-O-S-Pb isotopes source of ore-forming fluids and metals the Yinchanggou-Qiluogou Pb-Zn deposit southwest China |
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