Revised chronology of the middle−upper Cenozoic succession in the Tuotuohe Basin, central-northern Tibetan Plateau, and its paleoelevation implications

Abstract

Currently, the climatic implications associated with the Cenozoic tectonic history and growth mechanisms of the Tibetan Plateau lack consensus and remain controversial. This is due in part to chronological uncertainties and few paleoelevation records distributed in the central to northern Tibetan Plateau, which we address here with the development of a robust chronology (using magnetostratigraphy, biostratigraphy, detrital zircons, and regional radiochronologic dating) and a paleoelevation reconstruction for the Tuotuohe Basin (central-northern Tibet). We refined the age of the Tuotuohe Formation (37−33 Ma), Yaxicuo Formation (33−23.6 Ma), and Wudaoliang Formation (23.6−19.7 Ma). We estimated early Oligocene (ca. 29 Ma) paleotemperatures of the Tuotuohe Basin from 11 °C to 16.1 °C, which correspond to paleoelevations of 2.9 km (±0.4 km) when the relative humidity is 64% and 2.5 km (±0.5 km) when this value is 75%, using various methods including ostracod assemblages, gastropods, charophytes, branched glycerol dialkyl glycerol tetraether analysis, regional empirical formulas, and climate model simulation. Paleoelevation data and existing geological evidence in the vicinity indicate that late Eocene to late Oligocene uplift was associated with upper-crustal shortening. Since the middle Miocene, uplift has been associated with convective removal of lithospheric mantle and/or lower-crustal flow beneath the Hoh Xil Basin.