Late Cenozoic Geomorphic process in the northeastern Tibetan Plateau: Evidence from U-Pb age spectra of detrital zircons in the Wuwei Basin, NW China

The Cenozoic intensive uplift of the Tibetan Plateau and its northeastward expansion have had an important impact on the tectonic evolution, landform changes, and atmospheric circulation in the Asian interior. However the plateau uplift process is controversial, especially when did the initial time of the deformation on the northeastern plateau. The Cenozoic deposits in the northeastern Tibetan Plateau provide an ideal record for understanding the uplift and the geomorphic evolution in NW China. In this study, we measured U-Pb age spectra of detrital zircons collected from sand layers within the borehole WW-01 from the Wuwei Basin in the northeastern Tibetan Plateau, which ages of sand layer in the borehole WW-01 ranges from 10.34-0.09 Ma. Based on the long-term source variations of provenance of sands in the Wuwei Basin, combined with the existing structural and sedimentological data, our work reveals the Cenozoic uplift and geomorphic process of the northeastern Tibetan Plateau. Our results indicate that: (1) The dominant provenance of sediments in the Wuwei Basin was derived from Qilianshan Orogenic Belt (QOB) at 10.34-9.51 Ma, 8.18 Ma, 2.02-0.09 Ma, and the Alxa Block (AB) at 8.69 Ma and 8.14-4.51 Ma. (2) The two dominant provenance area transitions at 9.51-8.69 Ma and 8.18-8.14 Ma were controlled by the closely related to the pre-existing landforms of the basin and its periphery. And the two provenance transitions of 8.69-8.18 Ma and 4.51-2.02 Ma were prevailing in the uplift of the northeastern Tibetan Plateau. (3) Provenance analysis, integrated with the sedimentary and structural analysis, shows that the initial uplift of the northeastern Tibetan Plateau in the Cenozoic was ca. 8.25 Ma, and the last uplift occurred at ca. 2.58 Ma, corresponding to the geomorphological formation of the northeastern Tibetan Plateau.

Keywords: Northeastern Tibetan Plateau, Wuwei Basin, geomorphic evolution, uplift, Zircon U-Pb age, provenance analysis