The Tectonic Evolution In The Region Of Alagou At The East Segment Of The West Tianshan From Upper-Paleozoic

At present, although there are already many discussions for the crust fexture and tectonic evolution of Tianshan, Xinjiang, the research of the tectonic evolution for the study area were mainly on the specialist routes with convenient transit like the Du-Ku road, which is limited by the transit, and there are some disputes. The study region locates the connected position between the East and west Tianshan, through two samsaras 1:50000 regional geologic mineral examination and mapping from Xinjiang Autonomous Region, the tectonic environments and the importance for the tectonic evolution of the tectonic elements in the study region are comprehensively judged depend on gathering amount of field and interior geologic materials and dates. The aim is to discuss the partly regional tectonic evolution in Tianshan orogenic belt more concrete and comprehensive by combining the regional tectonic evolution of Tianshan tectonic belt, and it will guide the research of the connection of the East and West Tianshan.The study region locates on the combinative region of Kazakhstan-Junggar Plate and Tarim Plate, which belongs to the east of the West Tianshan. Bindaban-Xiarega Fault runs through this area in northwest-west orientation, it has the change from northward nappe to southward overthrust depended on the geologic and geophysical datas, the south of the fault is the Paleozoic composite arc belt of Boluokenu belongs to The Mid Tianshan district; and the north of the fault belongs to the North Tianshan tectonic district, which is futherly divided into the Upper Paleozoic trench-arc belt of Yilianhabierga and the Upper Paleozoic arc belt of Dananhu in the south divided by the Sumutexi-Alagou fault which is detachment fault and the Upper Paleozoic back-arc taphrogenic basin of Bogeda in the north by the Hongwuyueqiao -Sumutedaban fault, which is northward overthrust. Depending on the research on the field and the microstructure and fabric analysis in indoors, the Bindaban-Xiarega Ductile shear zone is divided into four main stages: brittle-ductile compressional shear - ductile compressional shear - ductile-brittle strike-slip shear - brittle deformation.Using the accurate tectonic environmental judgment through the comprehensive contrast of the petrologic, lithogeochemical, remote sensing geology and deformational characteristics in indoors and macroscopic characteristics in field on the tectonic elements, the volcanic rock in the Paleozoic composite arc belt of Boluokenu indicate the island arc environment, the multiple magma intrusion embodies the progress of the procollision continental-margin arc turn into syncollision volcanic arc, and there are one Metamorphic Core Complex may exist at Upper Proterozoic period in the Mid Tianshan; the Tiangeer formation in the Upper Paleozoic trench-arc belt of Yilianhabierga indicate the oceanic volcanic-arc environment, the later intrusional Carboniferous granite is the tectonic magmatic product of the oceanic island-arc, and constitute a complete trench-arc system; the Xiaorequanzi formation in the Upper Paleozoic arc belt of Dananhu display the continental crust island-arc environment; the Upper Paleozoic back-arc taphrogenic basin of Bogeda is compressional back-arc basin in Carboniferous, and turn into downfaulted tectonic basin in Permian, it reflect the collisional orogeny mainly occurred among the Upper Carboniferous and the Permian, and the downfaulted basin in Mesozonic Era is intracontinent pull-expansion extensional environment.Combining the achievement of the tectonic evolutional research in the past, the tectonic evolution in the research region is divided into four main stages: the formation-development-close of the North Tianshan Ocean evolution stage at Proterozoic - Lower Paleozoic; the limted oceanic basin pull-expansion to collision orogeny stage at Devonian-Carboniferous; the intracontinent extensional taphrogenic stage at Permian-Mesozoic Era and the intracontinent differential subsidence stage at Cenozoic.