The Geometry and Kinematics of the Kashi-Aksu Foreland Thrust System, Northwestern Margin of the Tarim Basin

Abstract

Abstract

The Kashi-Aksu thrust system lies on 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 based on surface investigation, interpretation of available seismic profiles and other geophysical data. The thrust system can be divided into three zones based on variations in structural style. The western and central zones are characterized by stacked structural wedges involving multiple detachment levels and imbricates involving a single detachment level, while the eastern zone exhibits basement-involved shortening occurring through reactivation of preexisting basement faults. The mid-eastern region of the thrust system developed through structural uplift as a foreland of the distant southern Tian Shan and through contractional subsidence under the influence of the Wushi Sag to the north. Sequential restored sections illustrate the kinematics of the foreland thrust system, they suggest the amount of shortening varies from 47.4∼57 km in the western and central zones to 27 km in the eastern zone. The average shortening rate since 5.3 Ma also varies laterally, from 8.7∼10.7 mm/a in the western and central zones to 2 mm/a in the east. We propose lateral variations in preexisting structure and changes in stratigraphic configuration exert major control on the along-strike variation of late Cenozoic deformation.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016