Basement Transverse Faults in Kuqa Foreland Basin, Northwest China and Their Significance in Petroleum Geology

Abstract

Researchers have emphasized the significance of transverse faults in basin evolution and petroleum geology. However, the transverse faults in the Kuqa Foreland Basin, the most important gas producing area in China have scarcely been studied. Based on field observation, gravity data, satellite images, focal mechanism solutions, and seismic data, we identified and calibrated a few widely-spaced approximately NS trending transverse strike-slip faults separating major structural units, and clarified the geometry and kinematics of these transverse faults seated under thrust faults. These reactivated basement faults, which inherited from Paleozoic deformation, controlled salt diapir, sedimentary cover deformation, and other elements relevant to gas accumulation and enrichment. In the Kuqa Foreland Basin, two major structural domains can be distinguished. A domain of NNE trending sinistral faults in its northern part implies that fault-bounded blocks may have rotated clockwise about vertical axes. In contrast, the predominance of NW trending dextral faults in its southern part implies that fault-bounded blocks may have rotated counterclockwise about vertical axes. We proposed a tectonic model in which crustal blocks are bounded by strike-slip faults in a zone of simple shear rotation about vertical axes. The domains of strike-slip and thrust faults in the basement suggest that some of the convergence between South Tienshan plate and Tarim plate could have been accommodated by rotation and possible lateral movement of crust along transverse faults, as well as by obvious crustal shortening and thickening along thrust faults.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015