Formation and re-orientation of the Suerkuli Basin within the Altyn Tagh in northeastern Tibetan Plateau since late Miocene

The Altyn Tagh Fault (ATF) had formed in Eocene time, however, the temporal evolution of slip along the fault remains elusive, despite its important role in governing growth of the Tibetan Plateau (TP) and evaluating models of continental lithosphere deformation. Here we perform a high-resolution magnetostratigraphic study on Neogene sediments from the Suerkuli Basin, a small basin located between two active strands of the ATF. Results show that both depositional environment and the sedimentation rate changed at about 5.4 and 6 Ma, respectively. Lithofacies shift from conglomerates and sandstones with parallel and cross beddings to mudstones with horizontal bedding, suggesting a sedimentary fluvial to lacustrine depositional environment shift. Even aridification increased over northern China, from the Tarim Basin to the Qaidam Basin, during late Miocene to early Pliocene times, lacustrine deposition had started in the Suerkuli Basin still. We argue that an increase in slip rate along the ATF triggered concurrently forming of the intermontane basin. The inferred timing of increased slip-rate on the ATF coincides with a variation in movement of the Indian Plate relative to Eurasian Plate since Late Miocene-Early Pliocene time. Our work suggests that a re-orientation of crustal shortening and deformation in the northern TP began since late Miocene and supports the idea that the modern boundary of the TP orogen had rejuvenated to adjust deformation in plate boundary conditions