Geochemical Characteristics And Genesis Of Mengxi Cu Deposit In The Eastern Junggar, Xinjiang

Mengxi copper deposit is located at the eastern segment of Xiemisitai-Yemaquan-Qiongheba arc in Xinjiang, the arc is one of the most important metallogenic of Central Asia.The ore bodies are hosted tuff of Mid-late Ordovicion Huangcaopo Group, the plagioclasegranite porphyry intrusion plays a very important role in the formation of the deposit. On thebasis of petrology, ore deposit geology,geochemical, ziroc U-Pb geochronology, this studymakes investigation on geological characteristics of the deposit,age and genesis of rock,metallogenic material source and genesis of the deposit, extract the prospecting information,and established the prospecting model.The geochemical and Sr-Nd-Pb isotop research of porphyry bodies in Mengxi mine showthat rocks are peraluminous calc-alkaline, enriched in large-ion lithophile elements Rb, Ba, U,K, Sr and depleted in high field strength elements Th, Nb, Ta, Nd, Ti. Through the studies onporphyry bodies, it is identified for rock bodies characterized with low (87Sr/86Sr)ⅰratio(0.70465～0.70537) and high Nd(t) value (-2.2～6.6). The research of Pb isotopic indicatesthat magma of porphyry bodies is originated from partial melting EMI, and mixed with thelower crustal matter. Comprehensive analysis that the metallogenic material sources migmaby enriched mantle metasomatic Subduction of oceanic crust material, formed in arcenvironment. Zircon U-Pb dating results suggest that porphyry formed in late Silurian（410±11Ma）, Zircon cores age of443.6±2.3Ma, show the age of magma source area.The S-Pb isotope and electron probe of pyrite in ores indicated the following cases:34Svalues range very small, from-2.1‰to0.3‰, indicating that sulfur of pyrite may be sourcedfrom magmatic rocks. Pb isotope values have a relatively wide variative range, which showthat originated from the mantle mixed with a few upper crust or stratum. S/Se of pyritebetween1142.34to4895.455, its formation is related to magmatic hydrothermal.Combination with background value of Huangcaopo Group and polished section, state clearlythat Huangcaopo Group provided a lot of material sources, as the main source bed. Mengxicopper deposit is a volcanic sedimentary and late thermal fluid overprint deposit.Extraction of ore prospecting information of geologic, geophysical, geochemical,Mid-late Ordovicion Huangcaopo Group, Regional deep fault, Plagioclase granite porphyry,High gravity, high polarization, middle magnetic anomaly, middle resistivity regions and Cu,Mo, Au, Zn, As, Sb and W elements geochemical anomaly distribution area. Established thefollowing prospecting model：(1) Mid-late Ordovicion Huangcaopo Group are favorable ore area;(2) Regional deep fault, especially the fracture interchange are favorable formineralization;(3) Plagioclase granite porphyry intrusion, especially the contact belt betweenthe rocks and stratums mineralization more easily;(4) High gravity, high polarization, middlemagnetic anomaly, middle resistivity regions easily mineralization;(5) Cu, Mo, Au, Zn, As, Sand W elements, especially Cu, Mo, Au and Zn elements geochemical anomaly distributionarea has important implications for ore prospecting.