Acta Metallurgica Sinica
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LI Zhenli, YE Lin*, HUANG Zhilong, ZHOU Jiaxi, HU Yusi, NIAN Hongliang
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Abstract: The mineral assemblage in the MVT Pb-Zn deposits is generally simple because the copper minerals of this type of deposit are very rare. As one of the largest MVT deposits in the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn metallogenic domain, the Fule Pb-Zn deposit is hosted in the Permian Yangxin Formation dolostone, which is the youngest ore-bearing strata in the area, and the distance between Pb-Zn ore bodies and the Permian Emeishan basalts is less than 160 m. By means of microscopic, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrum (EDS) analysis, a great number of copper-bearing minerals were found in the deposit, including chalcopyrite, Zn-tennantite, tetrahedrite and malachite. These minerals occur as banded, vein and irregular, and replace sphalerite or pyrite. The research shows that the droplet chalcopyrite is distributed within sphalerite, implying that both of themsphalerite grain, or distributed at the edge of the sphalerite, indicating that it was formed later than that of Pb-Zn mineralization. The copper minerals mentioned in this study commonly occur in middle-low temperature hydrothermal deposits, in which the Zn-tennantite is a rare sulfosalts. The appearance of Zn-tennantite and tetrahedrite indicates an oxidizing environment, and malachite is a secondary mineral formed at supergene weathering stage. The paragenetic sequence in the deposit is inferred as follows: pyrite→sphalerite (droplet chalcopyrite)→galena→chalcopyrite→Zn-tennantite→tetrahedrite→malachite. Combined with the geologic and geochemical characteristics of this deposit, it is suggested that there are two possible sources of copper. Early-stage copper was derived mainly from the basement of the Kunyang group and the late-stage copper was likely stemmed from the upper Emeishan basalts, which are different from those of Pb and Zn derived mainly from the Kunyang Group in the deposit. The research provids new geological and geochemical evidence for understanding the genetic relationship between the Emeishan basalts and Pb-Zn mineralization in the SYG district.
Key words: Fule Pb-Zn deposit, chalcopyrite, Zn-tennantite, tetrahedrite, MVT deposits
LI Zhenli, YE Lin*, HUANG Zhilong, ZHOU Jiaxi, HU Yusi, NIAN Hongliang. Mineralogical Characteristics and Geological Significance of Copper Minerals in Fule Pb-Zn Deposit, Yunnan Province, China[J]. Acta Metallurgica Sinica.
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URL: https://geology.nju.edu.cn/EN/
https://geology.nju.edu.cn/EN/Y2018/V24/I2/200