Development and Interplay of Two Orthogonal Fault Systems in the NW Qaidam Basin, Northern Tibetan Plateau

How fold and thrust belts (FTBs) evolve over time space in a transpressional regime remains poorly understood. Based on high-resolution 3D seismic reflection data remote sensing images, we herein present detailed structural analysis of the Cenozoic faults NW margin Qaidam Basin that is bounded to north by left-reverse Altyn Tagh fault system. Two sets orthogonal, basement-involved with contrasting geometries, kinematics, temporal development are identified. One set consists generally E-W-striking, N-dipping, reverse component sinistral shear. They parallel or subparallel system, led southward tilting basement, formed local unconformity between middle Miocene Shangyoushashan formation underlying strata. developed an out-of-sequence order, were mostly active during 43.8–15.3 Ma but relatively tectonic quiescence limited weak reactivation since then. The second mainly composed NNW-striking dextral shear components. approximately perpendicular intensively ∼15.3 Ma, much later than initiation E-W-striking faults. Together published results, ascribe these two orthogonal as transition from transpression left lateral slip central segment interplayed each other ways: 1) older offset younger faults, 2) curved link preexisting Our findings reveal transpressional-dominated FTBs more complicated way contractional-dominated ones, site-based case studies needed primary principles.