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›› 2019, Vol. 36 ›› Issue (2): 196-207.DOI: 10.7523/j.issn.2095-6134.2019.02.007

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Three-dimensional numerical modeling of the tectonic evolution of the serial basins in the Hexi Corridor in Northwest China

LI Weilin, CHENG Huihong, ZHANG Huai, SHI Yaolin   

  1. Key Laboratory of Computational Geodynamics of CAS, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2018-02-13 Revised:2018-03-28 Online:2019-03-15

Abstract: The Hexi Corridor, located in the northeastern margin of Qinghai-Tibet Plateau, is the leading edge of northeastern expanding of Qinghai-Tibet Plateau. In the northeastern thrusting of Qinghai-Tibet Plateau, there forms the landscape of basins and mountains in the Hexi Corridor, which is an ideal area for studying the tectonic evolution of the Cenozoic basins. The four basins, Wuwei, Zhangye, Jiuquan, and Yumen basins, lay in the Hexi Corridor from the east to the west. Based on the Late Cenozoic tectonic environment in the Hexi Corridor and its adjacent areas, the geometric structure of the present basins and fault zones, GPS, and historical seismic data, we establish a three-dimensional visco-elastic-plastic finite element model to describe the tectonic evolution process of the serial basins in the Hexi Corridor dynamically and explore the effects of lateral inhomogeneity of the crust on the tectonic deformation in this area. The results of the simulation are shown as follows. 1) The hard secondary blocks in the Hexi Corridor form four basins in a sequence of left echelon arrangement in the model and they are separated by the NNW-NW faults. 2) Compared with other regions, the Qilian Mountains and the junction areas of the Hexi Corridor with the Qilian Mountains and the Alashan block generally uplift fast and the uplifting speed of the Northern Qilian Mountains is higher than that of the Southern Qilian Mountains. 3) Under the overall compression-torsion, there appears an approximate "pull-point tectonic structure" gap on the Elm Shan fault in the northern Qilian fault zone where the uplifting speed is slower than in the adjacent part on the fault. 4) In the Tarim and Alashan blocks, the upper crust sinks correspondingly and squeezes lower blocks, and thus the tectonic framework between the basins and the mountains forms. The results of the modeling reflect the evolution of the serial basins in the Hexi Corridor, explain the distribution of the current river network in the Qilian Mountains area, and reveal the potential power source of the northeastern thrusting of the northeastern Tibetan Plateau.

Key words: Hexi Corridor, Northeastern Tibetan Plateau, tectonic evolution, visco-elasto-plastic, finite element modeling

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