Erosion and dust emission driven by alternatively episodic water- and wind-dominated environments in the stony Hami Basin, East Asia

Abstract

Wind is one of the most dominant agents of erosion and dust production in arid basins within the continental interior of central Asia. However, the interactions between water and wind erosion in landscape evolution and dust production in stony deserts remain unclear. We present an integrated geomorphologic, sedimentologic, and chronologic study from the stony Hami Basin and propose a hypothesis on dust production that may apply to other stony East Asian deserts. We propose that precipitation-driven water erosion contributed to lowering the basin floor and dust emissions. A 10Be depth profile from an isolated terrace (TN3) yields an exposure age of 198.3 +17.9/−23.9 ka which is geologically consistent with the electron spin resonance ages of the lower elevation terraces (TN2 and TS2), suggesting that higher precipitation during interglacials led to the water erosion of the higher elevation terrace and deposition of the lower terrace during the late Pleistocene. Integrated with field investigation, we thus infer that recurrent water erosion plays an important role in exposing friable strata, releasing loose sediments from consolidated bedrock, and increasing the availability of fine particles for the wind to pick up. Intense wind, especially during glacial periods, lowered the basin floor and transported the eroded materials out of the intermontane internally drained basin. Our results show that alternately episodic wind erosion (during glacial periods) and water erosion (during interglacial periods) driven by climatic cycles jointly contributed to the lowering of the basin floor and dust production in the Hami Basin.