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Post-Collision Tectonism and Basin-Range Evolution in the Tianshan Belt

SHU Liang-shu1, GUO Zhao-jie2, ZHU Wen-bin1, LU Hua-fu1, WANG Bo1   

  1. 1. Department of Earth Sciences, Nanjing University, Nanjing 210093, China; 2. School of Earth and Space Sciences, Beijing University, Beijing 100083, China
  • Received:2004-09-20 Revised:2004-09-20 Online:2004-09-20 Published:2004-09-20

Abstract: The sub-E-W-striking Tianshan belt was built in the late stage of Paleozoic.evidenced by Permian foreland molasses of regional scale which indicate the uplifting of Tianshan belt and formation of foreland basin.During Triassic,this orogenic belt was peneplaned,and the basins parallel to orogenic belt were further developed.In the interval of Jurassic Paleogene,extensional tectonic activity withinplate split the peneplaned Tianshan region into a series of sub-E-W-striking extensional basins.Since Neogene,a collision between Indian and Eurasian plates took place in the southem side of Tianshan belt,causing a strong intra-continental deformation characterized by thrusting and folding. This event led to coupling of ranges and basins,yielding a mosaic basin-range landform of present time.The strong thrusting influenced the orogenic belt in the hinterland.The Mesozoic-Cenozoic brittle deformation superposed on the ductile deformed Paleozoic rocks,and the transpression structures and listric faults were strongly developed.The thrusting flakes moving toward basins are very common. The distinct kinematic features occur throughout different geological units.At the same time,ranges were strongly reuplifted,and the extensional basins were converted into compression basins. Some Mesozoic coal-bearing basins in the ranges were violently uplifted to 4 000 m high,and the altitude difference between basins and ranges was increased.The step-type thrust faults and related fault folds were developed commonly in the basins. Strong fold-thrust structures occurred in the connecting zone between basins and ranges, accompanied with local sub-E-W-striking strike slip faulting.In the Tianshan region.thrusting deformation is an important basin-range coupling mechanism.The folding and faulting of Mesozoic sedimentary rocks,active faulting,Jurassic coal layer self-ignition and formation of sintered rocks were resulted from Cenozoic tectonism.