WU Sha1, JIN Zhong-guo1,2*, ZHENG Ming-hong2, ZHENG Lun-wei2, LIU Ling2, ZENG Dao-guo3, CAI Guo-sheng3

(1. Institute of Resources and Environmental Engineering, Guizhou university , Guiyang 550025,China;
2. Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau, Guiyang 550005, China;
3. Academy of Geological and Mineral Exploration, Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau, Guiyang 550005, China)

Abstract: The Shanshulin Pb-Zn deposit is located in the southeastern section of the Weining - Shuicheng metallogenic belt and is a representative Pb-Zn deposit in the northwestern Guizhou metallogenic district. In this paper, based on field observation and microscopic identification, it is identified that there are pyrites of two stages, including the early one (PyⅠ) and the late one (PyⅡ), in this deposit. The PyⅠ was formed in the diagenetic stage of sedimentary rock and is limitedly distributed in the ore, while the PyⅡ is closely related to the lead-zinc mineralization with its obviously epigenetic characteristics. The PyⅡ could be formed by the recrystallization of the PyⅠ. It is suggested that the Pb-Zn mineralization is closely related to the late hydrothermal mineralization. In this paper, the LA-ICPMS in-situ testing technology was used to test and analyze trace elements of pyrites and sphalerites of different stages in the deposit. On the basis of summarizing geological characteristics of the deposit, the metallogenic process has been discussed and the genetic type of the deposit has been determined, in order to provide a new basis for understanding the lead-zinc mineralization of the Shanshulin deposit. The results show that pyrites contain various trace elements, among which Ag and Pb occurred in the form of microscopic mineral inclusions. Generally, Co/Ni ratios for pyrites of two stages are far less than 1.00. However, it is worth to notice that contents of Cu, Ag, Sb and Pb of the PyⅡ are 2-5 orders of magnitude higher than those of the PyⅠ, with large ranges of variation, suggesting that the ore-forming fluid of this stage is rich in ore-forming materials such as lead and zinc, and the deposit is of hydrothermal origin. In addition, sphalerites contain various trace elements such as Cu, Sb, As, Ga, Ge and In which occurred in the form of isomorphism. They are relatively enriched in Ge and Ga, but relatively depleted in In, with Cd/Fe ratios ranging from 0.08 to 300 (average 6.16), Zn/Cd ratios varying from 100 to 500 (average 223.08), and lg (Ga/Ge) values varying from -2.55 to 0.47 whose corresponding metallogenic temperatures varying from 93.7℃ to 212.6℃. Combined with calculated results by using the Frenze equation, the metallogenic temperatures are concentrated in the range of 197－213℃, indicating that the metallogenic temperature of the deposit belongs to the category of low temperature. Based on results of the geological characteristics and interpretations of genetic discrimination diagrams, it is believed that the Shanshulin Pb-Zn deposit belongs to the MVT Pb-Zn deposit.

Keywords: LA-ICPMS; characteristics of trace elements; metallogenic information; genesis of mineral deposit; the Shanshulin Pb-Zn deposit

ACTA MINERALOGICA SINICA Vol. 43, No. 4, 2023, Page 469