The Crustal Evolution At The East Segment Of The South Tianshan From Late Paleozoic

South Tianshan fold belt is located between the Tarim plate and the Kazakhstan plate,save the important message of Proterozoic and Paleozoic ocean basin evolution, is one of theideal areas to study the history of the development of the Tianshan orogenic belt. To this end,we selected Xinjiang1:50000Malan village, Xinjingzi and other four regional survey projectas the support to explore the east segment of the South Tianshan from the late Paleozoiccrustal evolution.The study area is located in Heshuo County, Xinjiang, Wushen Tara village, belongs tothe east segment of the South Tianshan. By the field measured sections and route surveys,indoor data collation and data analysis, combined with the results of previous studies, thetheory of plate tectonics as a guide, starting from the regional geological setting,sedimentology, petrology and geochemistry characteristics of the study area since the latePaleozoic crustal evolutio process: From the Early Devonian Aerpishimaibulake Fm to theEarly Carboniferous Gancaohu Fm, this area is shallow water-shelf sea-bathyal-shallow wateralternating sedimentary environment; Late Devonian, South Tianshan Ocean closed, butbetween the Tarim plate and the Central Tianshan plate there are still residual basin, twoplates is still in the aggregation state, local tension in the northern margin of the Tarim plate,induced by volcanic eruptions, forming this area Pochengzi Fm volcanic rocks; Graniteformation in this area is widely distributed between the age of305±1Ma-289±4Ma(zirconU-Pb), The age of the Late Carboniferous-Early Permian, are calc-alkaline series,crust-mantle magma mixing, formed in the late stage of the South Tianshan orogeny, mayrepresent the final closure of the South Tianshan oceanic basin in the Late Carboniferous. Thisarea exposed in the Silurian tectonic melange formed in the the Early CarboniferousMedium-term-Late Carboniferous Later period, of the Area belong to Yushugou-Tonghuashantectonic melange with the westward extension. From the analysis of the folds and faults of thestudy area, the area has experienced at least two major tectonic deformation, the first is theEarly Carboniferous NW-SE folding deformation; the second is Early Carboniferous the mid-late Carboniferous late NNEâ†'SSW to thrust nappe role, and is accompanied by a series of left-lateral strike-slip movement.Comprehensive think, South Tianshan ocean starts to contract, the oceanic crustsubducting under the northern part of the Yili-Central Tianshan plate in the late Silurianperiod; to the Middle Devonian final, Yili-Central Tianshan plate and Tarim plate firstcollision, the oceanic crust disappears; From the Late Devonian-Early Carboniferous, the eastsegment of South Tianshan region into the residual basin evolution stage; LateCarboniferous-Early Permian, the east segment of the South Tianshan region into thecontinent-continent collision stage, namely Yili-Central Tianshan plate and Tarim platecollision, the residual basin disappear, has now entered a stage of evolution within the board;Early Mesozoic, the east segment of the South Tianshan region in the post-orogenicdenudation, missing Triassic deposition; From the Jurassic, mountain faulted activitygradually became active; Paleogene–Neogene period, the rift of activities further expand; intothe Quaternary, the east segment of the South Tianshan region mainly as the sinistralstrike-slip movement and asymmetric fault block uplift, thus forming a modern multi-levelvalley terraces.