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Trace Elements Features of the Vein Quartzs, Arsenian Pyrites and Their Fluid Inclusions in Jinfeng (Lannigou) Gold Deposit, Guizhou Province, China

HU Ying1, CHEN Mao-hong1, 2, DONG Qing-ji1, HUANG Qing-wen1   

  1. 1. China University of Geosciences, Beijing 100083, China;2. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
  • Received:2009-12-20 Revised:2009-12-20 Online:2009-12-20 Published:2009-12-20

Abstract: Jinfeng (previously known as Lannigou) is the largest known Carlin-type gold deposit in the Yunnan-Guizhou-Guangxi triangle area of southwestern China. Arsenian pyrite is the most important Au-bearing mineral, and silicification with quartz veins is the well-marked hydrothermal alteration. The trace elements of arsenian pyrites, vein quartzs and fluid inclusions in these minerals were analyzed by ICP-MS in this paper. The results show that in contrast to wall rocks and upper crust, the arsenian pyrites are enriched in chalcophile elements, but depleted in V,Sr and HFSE. The syngenetic pyrites bear the similar features.The vein quartzs have high lithophile elements contents, as well as chalcophile elements, Mo and Bi. However, compared with the upper crust, they are poor in most elements. The trace elements in fluid inclusions are usually lower than in corresponding hosting minerals, but with consistent variation features. Combining with the REE data of corresponding minerals and inclusions, it is clear that the arsenian pyrites, vein quartzs and fluid inclusions in these minerals are depleted in HFSE, with the Th/La and Nb/La ratios less than 1, suggesting a Cl-rich character of the ore-forming fluids. The Co/Ni ratios of arsenian pyrites and fluid inclusions are also lower than 1, indicating a lower ore-forming temperature. Consequently, it is inferred that the ore-forming fluids were mainly derived from the sedimentary formation water of the basin.