Metellogeneses In Relation To The Meiling Cu-Zn(Au) Deposit In The Kalatage Ore Concentration Area, Eastern Tianshan Mountain, Xinjiang, NW China

Located in the Paleozoic Kalatage uplift along the southern margin of Tu-Ha basin in eastern Xinjiang, the Meiling deposit occurs in the superimposed Mesozoic volcanic basin upon the middle part of Late Paleozoic Dananhu-Tousuquan accretionary arc. The ore-bodies, are hosted by basic-neutral-acid volcanic, volcaniclastic and sub-volcanic rocks, consist of veinlet disseminated sulfide ore-bodies and a sulphide-silicate stock- work vein system.The results of ³⁹Ar-⁴⁰Ar dating of sericite from M2 orebody in the Meiling deposit yielded the isochron age of（264.7±5.7） Ma. The age date corresponds to the zircon LA-ICPMS U-Pb age of（317.4 ± 2.6） Ma for the mineralization of altered dacite porphyry from M2 orebody, the zircon Shrimp U-Pb age of（313.0 ± 6.5） Ma for the altered dacite porphyry mineralization from M12 orebody, the zircon Shrimp U-Pb age of（317.7 ± 4.4） Ma for the burgundy dacite from the footwall of the M12 orebody, these data convinced the authors that the rock forming age of the surrounding rock is about Late Carboniferous Period. The Rb-Sr isochron age from six sphalerite samples and two pyrite samples from M12 orebody is（301.0±3.8） Ma and the Rb-Sr isochron age from five sphalerite samples, two pyrite samples and one chalcopyrite sample from M1 orebody is（299.2±2.9） Ma. These dating results indicate that the Meiling deposit formed approximately 300 Ma ago during the Late Carboniferous Period.The fluid inclusions are mainly consisting of aqueous fluid inclusions, are characterized by very small and sparse and small gas to liquid ratios; the medium-low homogenization temperature（range from 117°C to 238°C） and the medium-low salinity（range from 2.4% to 9.3%）. The trapping pressure wary from 6.8 MPa to 60.6 MPa mineralized at 0.2 km to 2.0 km depths. The ore-forming fluid belongs to the H₂O-Na Cl system with the gas phase is mainly composed of H₂O, with minor CO₂, while the liquid phase is mainly composed of Na⁺, K⁺, Cl^- and SO₄^2-. The hydrogen and oxygen isotopic features of quartz fluid inclusions show that the δ¹⁸O_H2O value ranges from-5.75‰ to-2.61‰ while the δD value ranges from-136‰ to-117‰, so it indicated that the ore-forming fluid was the mixture of magmatic water and atomspheric water.Studies on trace element and REE characteristics of pyrite, chalcopyrite and sphalerite which are the main sulfide of the quartz vein from M1 orebody show that the ore-forming fluid should be the Cl-rich weakly reduced fluid. From the early to the late stage of the mineralization, the ore-forming fluid changed its characteristics, and these results show that the late ore-forming fluid may be subjected to extraneous hydrothermal fluid. The characteristics of element content and the ratio changes of the pair of element of the mainly sulfide of Meiling deposit show that Meiling deposit belongs to magmatic hydrothermal deposit, but it is also influenced by the superposed transformation of the volcanic action. The δ³⁴S values in the volcanic rock are between 1.4‰ and 4.4‰ and the δ34S values of sulfide are between-1.6‰ and 4.8‰ suggesting that sulfur mainly derived from magma, with the volcanic rock. Lead isotope study shows some characteristics of mantle source, which is a mixed source of magma crust and mantle.According to the previous research results and ombined with the results of this research, we have constructed model of Meiling epithermal ore deposit. Combination the field surveying and the results of this research, we point out the indicator for this type of deposits in the Kalatage ore concentration area based on volcanic mechanism, structural features and hydrothermal alteration zoning.