Miocene rapid strike-slip faulting along the Altyn Tagh Fault, North Tibet: Insight from sedimentology records in the Tula and Qaidam basins

Abstract

A better understanding of the kinematics of strike-slip faults in northern Tibet greatly affects our knowledge of the Cenozoic growth of the Tibetan plateau. Despite recent achievements in geometry and slip rate of the modern Altyn Tagh fault as well as the exhumation history of the basement rocks along the fault, how did the Altyn Tagh fault construct through time remains controversial. Here we combined sedimentological and geochronological datasets from the Anxi section in the remote Tula basin to reveal the source to sink system across the western segment of the Altyn Tagh fault through time. Compared with sedimentary records from other two sections (namely Caishiling and Eboliang sections) at the central segment of the Altyn Tagh fault, our study reveals that the Altyn Tagh Range consistently served as the major source of clastic materials for the Tula basin from the Early Jurassic to the Early Miocene, suggesting negligible strike-slip motion along the western segment of the Altyn Tagh fault before Miocene. However, the sediments in both Caishiling and Anxi sections show a consistent variation of composition through time, likely corresponding to the pre-Early Miocene strike-slip faulting along the central segment of the Altyn Tagh fault. Integrated with existing evidence of multistage mountain building process in orogenic belts in the northern Tibet, our inference of the differential initial rupture on different parts of the Altyn Tagh fault highlights a Middle Miocene reorganization of the deformation in the northern Tibetan plateau.