Geological And Geochemical Characteristics And Genesis Of Dabate Cu-Mo Deposit,Western Tianshan,Xinjiang

The Dabate is a typical porphyry Cu-Mo deposit in Western Tianshan. Thedeposit reserves of copper52,000tons, molybdenum5,600tons. Combining withpetrography, mineralography, the geochemistry of petrology and ore deposit,geochronology, this paper analyzed the nature and source of the ore-forming fluids,the genetic types of granite porphyry and rhyolite porphyry, the tectonic environmentof magma and the origin of the magma, and attempted to reveal the nature of themagma, and genesis of Dabate.In the Dabate Cu-Mo deposit, one copper and one molybdenum ore body havebeen found, and both of them are developed in the rhyolite porphyry, and areseparated from each other in space. Ore body can be seen on the surface, like abending of the plate, distribution within the contact zone of the rhyolite porphyry andtuff; Molybdenum ore body is concealed deposits, like a curved convex mirror body,near the granite porphyry. The mining area has a typical alteration zone characteristicof the porphyry-type deposits. As the center copper mineralized rock outwards in turn:the K-feldspar belt, the sericitization belt, the silicification belt and the propyliticalteration belt. The main ore types include disseminated copper ore, disseminated-fine stockwork Cu-Mo ore and veinlets-stockwork molybdenum ore.The granite porphyry and porphyry in the area both are the highly fractionatedgranite （1） with high SiO₂, whole alkali （K₂O+Na₂O）, high mafic index （MF） andhigh felsic index （FI）;（2） all have great negative anomaly of Eu, the distributionmode of REE shows like a seagull, and tetrad effect;（3） the component of minorelements enrich in Rb, K, Th、Ta、Zr、Hf、Y and REE，and extremely lose Sr, P andTi，with clear negative anomaly of Nb. Judgment highly fractionated granitoids isvery difficult, but whether it is highly fractionated type I, S or A high degree ofcrystallization differentiation are one of the typical characteristics of theporphyry-type deposits.The ore-forming fluid has the medium temperature, a low salinity, and shallowdepth （0.53¹.32km）, average0.79km; Metallogenic environment aerobic fugacity is low, weak acid, reduction and other features.The Dabate mineralization porphyry emplacement environment was theextensional environment of the intraplate setting after plate collision in the late ofCarboniferous and Permian early. Experimental result of the molybdenite Re-Osisochron age is300.3±2.1Ma, and shows that the Daba Te mineralization age is theend of the Late Carboniferous.In summary, Dabate Cu-Mo deposit the rhyolite porphyry and granite porphyryemplaced in the intraplate setting after plate collision in the late of Carboniferous andPermian early, and had the nature of mantle-derived magma underplating causes.Then magma emplaced in the ultra-shallow, and generated the porphyry Cu-Momineralization.