Evolution of the North Qinling Mountains since the Eocene: Evidence from provenance analysis of Cenozoic sediments of the Weihe Basin, central China

The Qinling Mountains are a major climatic and geographical boundary, separating both the semi-humid and humid climate regions and two major river drainages in China. The Qinling Mountains have experienced significant uplift during the Cenozoic, which resulted in their development as a major environmental boundary. However, despite the availability of multiple types of evidence, ranging from low-temperature thermochronology to geomorphic features, the Cenozoic uplift history of the Qinling Mountains remains controversial. The North Qinling-Weihe Basin is an extensional mountain-graben system that developed since the Eocene. The sedimentary processes and provenance changes of the Cenozoic deposits in the Weihe Basin can provide valuable evidence of the uplift history of the North Qinling Mountains since ca. 46 Ma. In this study, we obtained new detrital zircon U-Pb ages from 37 horizons in the Cenozoic depositional sequence and five samples from modern rivers of the Weihe Basin. Our data reveal that the topography of the North Qinling Mountain-Weihe Basin was established by at least the middle Eocene. Stepwise accelerated growth and eastward migration of the North Qinling Mountains occurred at ca. 34 Ma, the middle Miocene, and in the Pliocene to Pleistocene. We propose that the modern-like landscape of China, with the Qinling Mountains as the major north-south boundary, was established from the latest Eocene to early Oligocene onward.