Variations of thick-skinned deformation along tumuxiuke thrust in Bachu uplift of Tarim Basin, northwestern China

摘要

The curved Tumuxiuke thrust is the northeastern boundary of the Bachu uplift in the Tarim Basin. Based on the interpretation of 2D seismic reflection sections, thick-skinned deformation along the Tumuxiuke structural belt is characterized by monoclinal fault-propagation folds that alternate with push-up structures. The localization and patterns of thick-skinned deformation were controlled by pre-existing normal faults. The forward trishear modeling process further revealed the existence of short-cut thrusts branched from pre-existing normal faults and tested their effect on folding deformation. Monoclines decapitated by low-angle short-cut thrusts coexist with anticlines decapitated by high-angle inverted faults due to the selective inversion of pre-existing normal fault segments. Furthermore, the fault propagation to fault slip ratio (P/S) and the combined effect of multiple propagating thrusts determine the variations in the fold amplification rate and the growth-stratal architecture. The coeval activity of the western Kunlun orogen and the Tumuxiuke thrust in the Cenozoic indicates the far-field transmission of orogenic stress into the distal foreland. Under the approximately N-S-directed compressive stress, inverted structures in nearly W-E-striking segments exhibit monoclinal fault-propagation folds controlled by forethrusts; for the oblique NW-SE-striking segments, the transpressional deformation was partitioned into the frontal contractional deformation zone and the backlimb strike-slip zone.