The Tectonic Segmentation and Hydrocarbon Exploration of the Foreland Thrust Belt in the Northwestern Tarim Basin

The structural style varies sharply in the foreland thrust belt along the northwestern margin of the Tarim basin,where contractional deformation occurred due to the rejuvenation of the southern Tian Shan in the late Cenozoic.Structural styles and their formation can be understood through construction of regional structural models on the basis of surface investigation,interpretation of available seismic profiles and other geophysical data.The thrust belt can be divided into seven segments in the light of difference in structural styles.They are the north Kashi fold zone,the Bapanshuimo fold zone,the Keping fold zone,the Wensu uplift,the Wushi fold zone,the Baicheng fold zone and the north Yangxia fold zone from west to east.The Wensu uplift exhibits basement-involved shortening,which occurs through reactivation of pre-existing basement faults,while the other fold zones are characterized by stacked structural wedges involving multiple detachment levels and also possibly a single detachment level.The structural styles and the deformation kinematics indicate that the central part of the thrust belt,such as the Wushi fold zone and Wensu uplift,is the key part for lateral structural transferring in the foreland thrust belt.Sequential restored sections illustrating the kinematics of the foreland thrust belt,suggest that the amount of shortening varies from 8.7 to 64.5 km.Therefore,we propose that the lateral variations in the pre-existing structure and changes in stratigraphic configuration play a major control role on the along-strike variation of late Cenozoic deformation.