YANG Song-ping1, ZHOU Jia-xi2, 3*, XU Lei1, LU Mao-da1, MENG Qing-tian1, ZHANG Kun1, YOU Jia-gui1
(1. No. 104 Geological Team, Bureau of Geology and Mineral Exploration and Development of Guizhou Province, Duyun 558000, China;
2. School of Resource Environment and Earth Science, Yunnan University, Kunming 650504, China;
3. Stake Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China)
Abstract: The Wulonggou Pb-Zn deposit is a typical representative of Pb-Zn deposits in the Sandu-Danzhai (Sandan) polymetallic metallogenic belt and is adjacent to the Miaolong Au-Sb deposit. So far, no report on its geology and geochemistry has been presented, thus little is known about its genetic mechanism. Based on the systematic geological study, the S isotopic geochemistry of sulfide minerals has been carried out in this paper in order to reveal the source and evolution of the mineralizer elements of the Wulonggou deposit, and to provide a geochemical basis for understanding its formation mechanism. Orebodies of the Wulonggou Pb-Zn deposit occurred in silty dolostone of the Sinian Doushantuo Formation and are obviously controlled by the NE-, NW- and SN-trending composite structures. The ore bodies are lenticular, with massive, veining, and dissemination structures for its ores. The sulfide minerals are mainly sphalerite, galena and pyrite, and the gangue minerals are mainly dolomite/calcite and quartz with occasional barite. Sulfide minerals have granular, cataclastic, and metasomatic textures. The geological characteristics of this deposit indicate that it has post-ore properties. The δ34S values of sulfides, varying from 10.9‰ to 16.5‰, are lower than those of sulfides in the Sandu Niuchang and Duyun Niujiaotang Pb-Zn deposits that are hosted in early Cambrian carbonate rocks in the adjacent area (all>20‰), and lower than those of the Sinian-Cambrian seawater sulfate (20‰－35‰). It can be seen that reduced S of the Wulonggou deposit could be produced by the marine sulfate thermochemical reduction (TSR). The temperature of TSR or the input of other S sources could be the main reason resulting in its lower δ34S values than those of the adjacent deposits. In summary, it is believed that the Wulonggou deposit belongs to an epigenetic hydrothermal deposit that is controlled by structure and lithology, and its S was mainly sourced from the marine sulfate. Due to the lack of other geochemical and chronological constraints, to confirm whether it is an MVT deposit or not requires further research.
Keywords: ore deposit geology; mineral structure and texture; S isotopes; source of ore-forming materials; the Wulonggou Pb-Zn deposit
