WANG Hao-yu1,2, YE Lin1*, HU Yu-si1,2, WEI Chen1,2, LI Zhen-li1,2, HUANG Zhi-long1, SHUANG Yan3
(1. State Key Lab of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China;
3. Chongqing Key Laboratory of Exogenic Mineralization and Mine Environment, Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China)
Abstract: The Western Hunan？Eastern Guizhou Pb？Zn metallogenic belt, located in southeast margin of the Yangtze Block, is an important part of the South China large-scale low-temperature metallogenic domain. More and more studies have shown that the Pb？Zn deposits in the belt belong to the MVT type of Pb-Zn deposit. However, researches on the enrichment characteristics and existing forms of critical metals (Ge and Ga, etc.) in those deposits are very limited. The Laochangping Pb？Zn deposit of the southeastern Chongqing, located in the northwest part of the metallogenic belt, is the largest Pb-Zn deposit in Chongqing City. Based on the LA-ICPMS in-situ analysis, combined with the time-resolved depth profiles, we have realized the features of trace elements in sphalerites from the Laochangping deposit, realved the distribution regulation and existing forms of critical metals of Ge and Ga in sphalerites of the deposit, discussed their substitution mechanisms in sphalerites, and provided practical basis for the comprehensive utilization of critical metals of Ge and Ga. The results show that the sphalerite of the Laochangping deposit is characterized by the enrichment of Cd, Ga, Ge, and Fe and depletion of Mn, Co, Ni, and In. The sphalerite was formed in the medium-low temperature environment. Both Ge and Ga contents meetan the requirements of industrial grades for the associated Ga and Ge elements. The existing forms of Ga and Ge are dominated by the isomorphism. The uneven distribution of Ge and Ga in sphalerites is an important feature. Cu is a key factor controlling the enrichment of Ge and Ga in the sphalerite, with the possible coupling substitution modes of 3Zn2+？Ge4++2Cu+ and 2Zn2+？Ga3++Cu+. In general, the compositional characteristics of trace elements in sphalerites from the deposit are basically consistent with those of the MVT Pb-Zn deposit. Combined with other geological and geochemical characteristics of the Laochangping deposit, it is suggested that the Laochangping deposit belongs to the MVT type of Pb-Zn deposit.
Keywords: Sphalerite; critical metals; Ge and Ga; LA-ICPMS; MVT type of Pb-Zn deposit; the Laochangping Pb-Zn deposit in the southeastern Chongqing
ACTA MINERALOGICA SINICA Vol. 41, No.6, 2021, page 623-634
