Low elevation of the northern Lhasa terrane in the Eocene: Implications for relief development in south Tibet

Xu Q, Ding L, Hetzel R, Yue Y, Rades EF

Abstract

The uplift history of Tibet is crucial for understanding the geodynamic and paleoclimatologic evolution of Asia, however the pattern of plateau uplift through space and time remains unresolved. We use stable isotope data for paleosol carbonates to reconstruct the Eocene (~46Ma) elevation of the Tangra Yum Co region (northern Lhasa terrane). The difference between the oxygen isotopic composition of the studied paleosols and Eocene surface water near the source of the Indian monsoon indicates a paleoelevation of 2590(+730/-910)m for Tangra Yum Co (present altitude: ~4600m). A similar paleoaltitude is obtained by comparing our data with modern soils and taking past environmental changes into account. Combining our results with published paleoelevation estimates in Tibet suggests a significant relief (~2km) during the Eocene, when a low-lying basin in the northern Lhasa terrane was bounded by the Qiangtang and Gangdese mountain belts farther north and south, respectively.