CHEN Xiao-dong1,2, LI You-guo1, LI Min-tong2, XU Yuan-ping2, XIE Wan-hong2, ZHOU Hong-bing2, SUN Chong-bo2
(1. College of Earth Science, Chengdu University of Technology, Chengdu 610059, China；
2. Hydro-Engineering Party of Sichuan Metallurgical Geology&Exploration Bureau, Chengdu 611730, China)
Abstract: The Nagengkangqieergou silver deposit, situated in north side of the Kunzhong fault in the eastern segment of the Eastern Kunlun orogenic belt, is a recently discovered large-scale independent hydrothermal vein-type deposit, whose orebodies are mainly controlled by the NW-trending faults, in Qinghai Province. This is the first time to have undertaken a systematic study on the characteristics of representative sulfides from the Nagengkangqieergou silver deposit in this paper. The results of microscopic mineralography observation and electron microprobe analysis show that sulfides of the Elashan Formation mainly include sphalerite, galena, and pyrite, while those of the Jinshuikou Group include sphalerite, galena, pyrite, chalcopyrite, marcasite, arsenopyrite, stannite, and pyrrhotite. Silver minerals including native silver and argentite are in close spatial association with the distribution of sphalerite, arsenopyrite and stannite. Besides independent silver minerals, the Ag occurred partly in galena in isomorphism forms. In addition, the contents of Ag in galena crystals from the Jinshuikou Group are obviously different to those from the Elashan Formation, with average Ag contents of 0.33% and 0.64%, respectively. There is scarcely any Ag in other sulfides. Moreover, the compositional and typomorphic characteristics of sphalerite, galena, and pyrite indicate that the mineralization of the Nagengkangqieergou silver deposit is genetically associated with volcanic activities, and the ore-forming fluids associated with the Ag mineralization in both ore-bearing strata show remarkable differences in temperature, composition, and sulfur fugacity.
Keywords: the Nagengkangqieergou silver deposit; sulfides; electron microprobe; mineralogical characteristics; the Eastern Kunlun orogenic belt
ACTA MINERALOGICA SINICA Vol. 39, No.1, 2019, page 64-74
