Early Miocene Paleoaltitude of the Tuotuohe Basin, Central-Northern Tibetan Plateau and its Tectonic Implications

Reconstruction of the paleoaltitude history of the Tibetan Plateau is critical for understanding the linkage between tectonics and its effect on regional and global climate change. Presently, most of the paleoaltitude studies are concentrated on the southern and southeastern part of the Tibetan Plateau, and few studies have been conducted in the central-northern part. In this paper we focused on the Wudaoliang Formation in the Tuotuohe Basin, central to northern Tibetan Plateau, to reconstruct paleoaltitude based on carbonate oxygen isotopes. The carbonate samples are primary or have experienced an early stage of digenesis. Based on the thermodynamic and empirical model results, the paleoaltitude of the Wudaoliang Formation is found to be around 2700-3260 m (average of 2980 +/- 280 m) in the early Miocene (similar to 24 Ma). Integrating paleoaltitude results from Wudaoliang Basin and our results, we conclude that crustal shortening and tectonic activity were strong during the late Eocene to late Oligocene-early Miocene and relatively weak during the early Miocene in the central-northern Tibetan Plateau.