Leaf wax stable isotopes from Northern Tibetan Plateau: Implications for uplift and climate since 15 Ma

The growth of Tibetan Plateau is considered to have played a key role during the evolution of Asian climate. Our understanding of the relationship between the plateau growth and Asian climate changes is limited, however, due to the scarcity of well-dated sedimentary sequences that could provide parallel information of the evolution of elevation and climate. Here, we report a high-resolution time series record of the stable hydrogen isotopic composition of leaf-wax n-alkanes ( δ D n - alk ) from a continuous Neogene stratigraphic sequence (15–1.8 Ma) from the Qaidam basin on the northern Tibetan Plateau. These data are used to reconstruct the isotopic composition of meteoric waters ( δ D m ) and subsequently applied to interpret the history of paleotopography and climate in Qaidam. sults indicate four stages in the evolution of hydrology in the Qaidam basin. In Stage I (15 Ma to 10.4 Ma), δ D m gradually decreases from − 24.9 ‰ to − 75.5 ‰ , synchronous with a period of active tectonism. The estimated topographic growth of 2.1 ± 0.3 km is comparable to the height of Qaidam basin relative to the foreland Hexi Corridor. We note that C3 plants were dominant in this region since the Miocene; we take this as independent evidence that this area was mountainous before the C4 expansion in late Miocene and Pliocene. δ D m variability in subsequent stages appears to be related to shifts in dry and moist conditions and independent of topographical changes — a conclusion supported by other independent climatic records on the Tibetan Plateau. High δ D m values in Stage II (10.4 Ma to 6.9 Ma) are related to severe aridity, and Stage III (6.9 Ma to 4.1 Ma) is marked by low δ D m values, suggestive of moist conditions related to the strengthening East Asia Summer Monsoon. High δ D m values in Stage IV (4.1 Ma to 1.8 Ma) reflect a climate, drier than the present.