A Study On The Geological Chracteristics And The Mineralization Background Of Kekesai Cu-deposit In Awulale, Western Tianshan

Kekesai cooper deposit is situated at eastern Awulale metallogenic belt, western Tianshan Mountains.It is of theoretical and practical significance to study on the Geological chracteristics mineralization background since the absence of research about Kekesai cooper deposit and Cu-mineralization in eastern part of Awulale metallogenic belt.A series of systematic research that included geological documentation of section, drill core and trenches have been operated after conscientiously study the previous achievements and the synthesized geochemical and geophysical exploration information,so as to summerise the geological characteristics.Furthermore,this study conduct petrogeochemistry and geochronology test an analysis to discuss on the mineralization background and genetic type of the deposit.In this thesis, a series of systematic research about petrography, mineragraphy, analysis on geophysical and geochemical exploration have been done after conscientiously study the comprehensive previous achievements, combined with filed geological investigation to recongnize the basic geology. The ore bodys that contained disseminated, breccias, veinlet type ore are hosted in the Upper Carboniferous Yishenjilike Formation and the intrusive quartz-syenite of early Permian, which is controlled by fault structures, propylitization and ferritization widely developed.The volcanic rocks were formed in the early stage of late Carboniferous epoch.On the one hand,it shown some characteristic with depletion of some HFSE(Nb、Ta、Ti、P) and lower concentrations of them and the value of Nb/La<1,which indicated an assimilation and contamination progress;On the other hand, it possessed similar characteristics of bimodal volcanic rocks in a rift settings since the enrichment of Ce、Hf、Zr、Sm,which indicated a tectonic agent transformation.It can be explained as a post-subduction extensional tectonic setting that was related to a series of balance adjustment process and displayed as a lateral escape mechanism, which is under a compression environment in convergent boundary.The zircon LA-ICP-MS U-Pb age of quartz-syenite was yieled at 291 Ma, which suggested it was formed in early Permian. The petrogeochemistry indicated that the quartz-syenite belongs to alkaline “I” type granite.Even though it revealed the affinity to arc granites with LILEs enrichment and HFSEs(Nb、Ta、Ti、P) depletion,but it exhibited the general characteristics of within plate granite as the Nb/Ta value in the continental crust scope,and the Ba、Sr depletion. In general, the quartz-syenite formed in a post-collisional crustal extension setting.Based on the tectonic settings and mineralization background,combined with the ore-fabric characteristics, we can infer that The Cu elements were derived from magmatic hydrothermal and extraction in the volcanic rock formation,the sulfur isotope characteristics indicate that the migration and precipition of majority chalcocite is attributed to the postmagmatic hydrothermal solution.In conclusion, Kekesai Cooper deposit was closely related with the magma hydrothermalism of the Quartz-syenite and underwent leaching enrichment process subsequently.