Fluid inclusion study and ore genesis of the Talate Fe-Pb-Zn deposit in Altay, Xinjiang
Fluid inclusion study and ore genesis of the Talate Fe-Pb-Zn deposit in Altay, Xinjiang
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作者：
L. Deng
The Talate Fe-Pb-Zn deposit is located in Abagong poly-metallic metallogenic belt of the Altay Orogen. The ore bodies, occur as veins in the Kangbutiebao Formation which contains intermediate-acid marine volcanic rocks and terrigenous clastic sedimentary-carbonate rocks, and are jointly controlled by faults. Considering the mineral assemblages and crosscutting relations of veinlets, the mineralization process can be divided into four stages, from early to late, forming the skarn minerals, veins of quartz-oxide (QO), quartz-sulfide (QS) and quartz-carbonate (QC) assemblages. Among them the quartz-sulfide (galena-sphalerite±pyrrhotite±chalcopyrite) stage is the main Pb-Zn mineralization stage. Four compositional types of fluid inclusions are observed at the deposit, i.e. aqueous inclusions (W-type), pure CO2 inclusions (PC-type), CO2-NaCl-H2O inclusions (C-type) and daughter mineral-bearing inclusions (S-type). Microthermometric data and laser Raman analyses show that the quartz accompanying oxides contains all of the four inclusion types, with the W-type being predominant. They are mainly homogenized between 271℃ and 426℃. The salinities of fluid inclusions of the W- and C-types range from 0.5% to 22.4% NaCleqv, and those of the S-type fluid inclusions from 30.5% to 40.6% NaCleqv. The quartz of quartz-sulfide stage contains the W-, C- and PC-types of fluid inclusions, which are homogenized at temperature of 204~269℃, with salinities of 0.2%~15.6% NaCleqv. The minerals of quartz-carbonate stage have only the W-type fluid inclusions yielding homogeneous temperature of 175~211℃ and salinities of 1.1%~9.9% NaCleqv. The C-type fluid inclusions in quartz of the quartz-sulfide stage yield trapping pressures of 107MPa to 171MPa, corresponding to a depth of 4~6km. Holistically, the fluids in the quartz-oxide and quartz-sulfide stages are hypothermal, CO2-rich and high salinity, but in the quartz-carbonate stage are low salinity and CO2-poor. Fluid immiscibility and/or boiling are the main factors resulting in precipitation of metallic minerals. The geology and ore-forming fluid characteristics presented in this paper shows that the Talate Fe-Pb-Zn deposit was a typical skarn-type mineralization system formed in the continental collision orogeny.
