Cenozoic tectonosedimentary evolution of the Linxia Basin, northeast Tibetan Plateau based on an analysis of detrital zircon provenance

Abstract

The Linxia Basin is an important region for understanding the tectonism and uplift history in the northeast Tibetan Plateau, and also contains rich mammalian faunas of evolutionary significance. In this paper, we conduct a provenance study of Cenozoic sediments, relying primarily on U-Pb dating of detrital zircons, to investigate the exhumation history of surrounding terranes and to gain a better understanding of the relationship between tectonism, basin development and paleoenvironment.Samples were collected from the Maogou section in the central Linxia Basin, which has been recently dated by magnetostratigraphy. Detrital zircon populations show five UPb age groups of 65–350 Ma, 350–600 Ma, 600–1600 Ma, 1600–2200 Ma and 2200–2600 Ma; however, UPb age patterns varied up-section, indicating different sources at different times.Sediments from the lower part of the section (>27.8 Ma) were sourced from multiple regions, including the distal East Kunlun Shan, Qilian Shan, and Songpan–Ganzi terranes, and as well as the proximal West Qinling region. Contributions from the Songpan–Ganzi terrane increased considerably during the late Oligocene (27.8–23 Ma), as a result of strong tectonic movements of the northeastern Tibetan Plateau. During the early Miocene (23–17.2 Ma), the northern sources of the Laji Shan–Maxian Shan region supplied more sediments to the basin, indicating the uplift and exhumation of these mountain ranges. Until the middle Miocene (17.2–12.8 Ma), the Songpan-Ganzi terrane and the northern sources dominated the basin sediments, while the northern sources and the Jishi Shan region became increasingly important sources at around 11.6 Ma. This study explores the tectonosedimentary evolution of the Linxia Basin in the northeastern Tibetan Plateau, providing a reference for further research of the paleoclimate and mammalian evolution in this critical region.