Expansion of Dust Provenance and Aridification of Asia Since ∼7.2 Ma Revealed by Detrital Zircon U-Pb Dating

The relative importance of global cooling and Tibetan Plateau uplift in driving the aridification of Asia during the late Cenozoic is debated, largely due to the lack of appropriate proxy indicators. Here we address this problem by investigating changes in the source of Chinese loess and Red Clay, which is directly controlled by changes in the extent and distribution of the arid zone of Asia and the intensity of the East Asian winter monsoon, using zircon U-Pb dating of 27 levels in a near-continuous eolian sedimentary sequence in southern Chinese Loess Plateau. The results show that source regions expanded stepwise at similar to 7.2, similar to 2.6, 1.2-0.9Ma, and at the Last Glacial Maximum. These changes were synchronous with global cooling and ice cover expansion in the Northern Hemisphere, suggesting that the drivers of aridification of the Asian interior were intimately related to global cooling in the late Cenozoic. Plain Language Summary The arid and semiarid regions of Central Asia are one of the most important dust sources on Earth. Dust emitted from these regions is deposited in the Chinese Loess Plateau, the North Pacific Ocean, and even in Greenland, with broad environmental impacts. Although there is evidence that the drying of the Asian interior occurred gradually over several tens of million years, the driving factor remains unclear. Here we investigate the evolution of the sediment sources of the Chinese Loess Plateau and find that the changes in the source regions of wind-blown sediment were synchronous with global cooling since similar to 7.2 Ma. This indicates that the long-term aridification of the Asian interior was most likely driven by global cooling.