TANG Xiao-fei1,2, ZHANG Bo-wen1,2*, FENG Jing3, CHEN Chuan1,2, ZHAN Xin-zhong1,2
(1. Institute of Geology and Mines Engineering, Xinjiang University, Urumqi 830047, China;
2. Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt, Xinjiang University, Urumqi 830047, China;
3. Xinjiang Uygur Bureau of Geology and Mineral Resources, Uriimqi 830000, China)
Abstract: The Saibo copper polymetallic deposit, located in the Sailimu Lake－Sitai Haiquan copper-lead-zinc metallogenic belt in the Western Tianshan, is a newly discovered medium-large sized copper deposit as a result of the mineral exploration breakthrough in the area. Through the thin section authentication and the theremometric analysis of fluid inclusions, it is concluded that skarnization was developed in this deposit, and the mineralization stages can be divided into the retrograde skarn stage (S1), quartz-sulfide stage (S2), and quartz-carbonate stage (S3). Fluid inclusions were distinguished as Type I of the pure liquid one phase inclusion, Type IIa of the liquid-rich two-phase inclusions, Type IIb of the vapor-rich two-phase inclusion, Type IIIa of daughter mineral-bearing inclusion(with daughter mineral of halite), and Type IIIb of daughter mineral-bearing inclusion (with other daughter minerals rather than halite). There are several stages in the evolution process of ore-forming fluids. In the early-ore stage, the ore-forming fluid is characterized with high temperature, high salinity, and occurrence of a small amount of metal minerals. In the main-ore stage, the ore-forming fluid was characterized with relatively decreased temperature and salinity due to the mixing of meteoric water and a large amount of metal minerals were precipitated due to the fluid boiling. In the late-ore stage, the ore-forming fluid was characterized with relatively low temperature and salinity and the carbonation was developed. The C-H-O isotopic results show that the ore-forming fluid was mainly composed of the primary magmatic hydrothermal fluid in the early-ore stage but meteoric water in the late-ore stage. The sulfur and lead isotopic data indicate that the metallogenic material were sourced mainly from the mixture of crustal and mantle materials. In general, the Saibo copper polymetallic deposit belongs to a typical calc-skarn type of deposit which was formed in the magmatic arc setting of the active continental margin.
Keywords: The Western Tianshan; Saibo copper deposit; fluid inclusion; C-H-O isotopes; genesis discussion
ACTA MINERALOGICA SINICA Vol. 41, No.2, 2021, page 197-212
