The Study of Ore-forming Fluid of Gold Deposits in Western Junggar, Xinjiang

Abstract: Baobei gold deposit is located in east of Western Junggar of Xinjiang, and in the Early Carboniferous volcanic-sedimentary formation named as Tailegula group, which is basalt, tuff, and andesitic rocks. The Baobei gold deposit is mainly composed of gold–bearing quartz veins. It is composed of two types quartz: Barren coarse grains ivory-white quartz and ore-bearing fine grains smoke-gray quartz.There are three types of fluid inclusions in the different quartzs: Type I, one- and two-phase vapor-rich fluid inclusions, occurred isolated or clusters. Type II, two-phase vapor-liquid fluid inclusions. Type III, one- and two-phase liquid-rich fluid inclusions. According to Laser Raman spectrum, each of the three types fluid inclusions could be subdividable. Type I is CO2-CH4-H2O±N2 system (Ia) and CH4-H2O±N2 system (Ib).Type II is CO2-CH4-H2O±N2 system (IIa), CH4-H2O±N2 system (IIb) and H2O-rich (IIc). Type III is CH4-H2O system (IIIa) and H2O-rich (IIIb). There are all types of fluid inclusions occurred in one quartz grain with different filling degrees, as shows characteristic of fluid boiling. The ore-related homogenization temperatures vary between 240℃and 330℃,with a mode between 280℃and 300℃. And the salinities are between 1.74wt% and 6.46wt% NaCl eq. The distribution of fluid inclusions in quartzes is closely related to sulfide minerals.Comparing with Hatu gold deposit, we considered that the origin of ore-forming fluid and the cause of formation of gold mine in Western Junggar are complicated. In this region, each of all deposits formed by multi-stage, various fluid…
Key words: Western Junggar; Baobei gold deposit; fluid inclusion; laser Raman spectral analysis

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