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Extraction of Weak Structural Information and Evidences of Sinistral Strike-Slip in Kalpin Area,Xinjiang, Northwest China

FAN Xiang-tao1; LU Hua-fu1; SHI Huo-sheng1; GUO Hua-dong2; SHAO Yun2   

  1. 1, Department of Earth Sciences, Nanjing University, Nanjing 210093 China; 2, Laboratory of Remote Sensing Information Science, Chinese Academy of Sciences, Beijing 100101 China
  • Received:2000-03-20 Revised:2000-03-20 Online:2000-03-20 Published:2000-03-20

Abstract: The peculiar geomorphologic pattern of Kalpin area, northwest flank of Tarim Basin is represented by certain regular structural shapes on remote sensi ng images. These structure patterns are rich in information of kinematic and dyn amic characteristics of this area and could be used to reveal tectonic history a nd deformation characteristics of Tian Shan and Tarim Plates. Based on field stu dy and integrated processing of Landsat TM, SIR-A and hyperspectral images of K alpin area, as well as the radar image expressing surface features, we extracted weak structural information from the images and enhanced secondary-order struc tures and interface information of geologic bodies with thin covers.   The Kalpin ranges, comprising of strata from the Cambrian to the Permian, is co mposed of a series of thrust sheets of the Late Cenozoic. Interpretation of remo te sensing images and field surveying have revealed that there are two stri ke-slip fault bend contortions and a strike-slip fault propagation contortio n. Studies on the deformation of the thrust sheets and the reduplication of these sheetes in map view suggested that the force model of this area is determined by the sinistral strike-slip in east-west and northeast directions under the com pression from north to south.   After detailed study on the image characteristics and tectonic feature s of six sub-areas (A, B, C, D, E, F), we analyzed the characteristics of secon dary-order structural deformation, geological interfaces under thin covers, and the related deformation caused by sinistral strike slip in this area.   Sub-area A exhibits that several strata layers are cut off by the northweat tre nding fault, which forms the strike slip fault bend.   Sub-area B is the most distinctive north-south trending fault zone in this are a. It is a synthetic breakthrough fault of the sinistral strike-slip fault prop agation contortion in the east part of this area.   Sub-area C shows the deformation character of thrust sheets trending from EW to NE, which, together with the sinistral NS shearing belt in the sub-area B, for ms a northward extrusion structure towards north.   Sub-area D is a relative weak deformation area. The thrust sheets trend in NE d i rection continuously without large fractures. Tectonic stress is consumpted by f lexural and propagation deformations.   Sub-area E shows that the NE and SW terminal segments has been cut off by thrus t sheet sinistral strike-slip movement.   Sub-area F exhibits clearly an asymmetric twist of bedding lines of the Paleozo ic strata thrust sheet in the weak information. The thrust sheets form strike- sli p detachment contortion, indicating that it is a sinistral strike-slip trending in west-east direction.   The evidences presented in this paper demonstrated the nature of intensive sinis tral strike slip movement and therefore revealed the deformation pattern and kin ematic process of this area.