Extreme aridification since the beginning of the Pliocene in the Tarim Basin, western China

Mid-latitude Central Asia is characterized by an extreme arid landscape. Among the Central Asian deserts, the Taklimakan Desert is the largest shifting sand desert which is located in the rain shadow of the Tibetan Plateau and of the other central Asian high mountains. The formation of this desert is important for placing widespread aridification into a regional tectonic context at the western end of the Himalayan-Tibetan orogen. However, there still exists considerable controversy regarding the timing of desert formation, thus impeding our understanding of the climatic effects of the Tibetan uplift and regional environmental changes. Here we report new biostratigraphic age control and multiple high-resolution climatic records from the center of the Taklimakan Desert. Our results reveal dramatic environmental changes at ~ 5 Ma, suggesting that an extremely dry climate has prevailed since the beginning of the Pliocene, which is consistent with findings from a high-resolution borehole record about 670 km to the east in the same basin. The two records combined demonstrate that an extremely dry environment prevailed in the entire Tarim Basin from approximately 5 Ma. This was related to the reduced transport of water vapor by westerlies in response to the retreat of the Paratethys Ocean driven by global climatic cooling, and the closed oceanic water-vapor pathway between the Pamir and the Tian Shan ranges driven by the ongoing India-Eurasia collision.