Oroclinal bending of the Saishitengshan arcuate belt and implications for strike-slip faulting of the Altyn Tagh Fault

Knowledge regarding the origin of the arcuate belts located south of the Altyn Tagh Fault (ATF) is important for understanding the evolution of the ATF. Here, we conduct a detailed paleomagnetic rotation study on two halves of the Saishitengshan arcuate belt (SAB) in the northern Qaidam Basin to better understand the ATF evolution. Paleomagnetic results reveal an similar to 25?degrees rotational difference between the two halves during deposition of the Shangganchaigou and Xiayoushashan formations. This rotational difference is consistent with the geometric trend change in the SAB, and its oroclinal bending is further constrained as having occurred during the middle to late Miocene (similar to 17-10 Ma) based on similar rotation of nearby Heishiqiu. Combined with other paleomagnetic results along the ATF, we propose that a transitional zone with remarkable counterclockwise rotations developed south of the fault due to the frictional dragging of the ATF, which is related to its tectonic transition from concentrated to distributed sinistral shear during the middle to late Miocene.