Title

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

Document Type

Article

Publication Date

3-15-2014

Abstract

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 ) 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 ) and subsequently applied to interpret the history of paleotopography and climate in Qaidam.Our results indicate four stages in the evolution of hydrology in the Qaidam basin. In Stage I (15 Ma to 10.4 Ma), δ 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 C plants were dominant in this region since the Miocene; we take this as independent evidence that this area was mountainous before the C expansion in late Miocene and Pliocene. δ 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 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 values, suggestive of moist conditions related to the strengthening East Asia Summer Monsoon. High δ values in Stage IV (4.1 Ma to 1.8 Ma) reflect a climate, drier than the present. © 2014 Elsevier B.V. D n-alk Dm Dm 3 4 Dm Dm Dm Dm

Publication Source (Journal or Book title)

Earth and Planetary Science Letters

First Page

186

Last Page

198

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