Modern sand supply of the Tengger Desert and temporal variations in sand provenance driven by northern Hemisphere glaciation

Knowledge of surface processes in source-to-sink system of sand is important for the development and utilization of natural resources in desert. However, the surface processes within Chinese deserts, especially their response to long-term global cooling since the Late Pliocene, are still poorly understood. Here, we use geochemical analyses of aeolian sand (63-500 mu m) samples from a drill core in the central Tengger Desert of China, together with widely-distributed surface samples, to elucidate the present and past surface processes. The main sand provenances for the southwestern and northeastern parts of the Tengger Desert are the northeastern Tibetan Plateau and the Alxa Block, respectively. After the inception of Northern Hemisphere glaciation at-2.7 Ma, the expansion of ice sheets in high northern latitudes was the major trigger of an increased sand supply from the Alxa Block to the desert hinterland, via the strengthening of the Siberian High. After the Mid-Pleistocene Transition (MPT), during-1.2-0.8 Ma, the development of mountain glaciers in the Tibetan Plateau was the major trigger of an enhanced fluvial sand supply from the northeastern Tibetan Plateau to the hinterland. Further, we propose that these two triggers may subsequently have caused substantial variations in the sand supply to most of the deserts surrounding the northern Tibetan Plateau rather than only the Tengger, due to the similarity of their sand supply mechanisms. And the enhanced fluvial sand supply from the northern Tibetan Plateau may be of significance to the continuous existence of a sand sea landscape in the surrounding basins during the post-MPT interval. Overall, our study suggests that glaciation in the high latitudes and the high mountains of the Northern Hemisphere have a significant impact on the two sand supply agents, i.e., wind and water, of Chinese deserts respectively.