Large-scale controls on the development of sand seas in northern China

摘要

Although sand seas are located in arid regions, given that the proportions of dune areas vary greatly from region to region they are clearly influenced by other factors as well as aridity. This paper discusses the distribution pattern and major features of sand seas and large fields of stabilized dunes in northern China, and demonstrates the main influences on their development. It appears that the availability of onsite loose sediments, not wind strength, is critical to the occurrence of the sand seas on a regional scale. Tectonic, endorheic basins or areas of alluvial fans or forelands of mountain ranges are advanta geous to the accumulation of fluvial sediments, and thus are ideal locations of large sand seas in an arid climate. The large dune fields currently stabilized by vegetation were active sand seas during the drier periods of the late Pleistocene and early Holocene. The distribution patterns of Chinese sand seas suggest that the height or size of the dunes in the sand seas are determined more by the availability of sands than any other potential factors. As the sand seas in China account for a large portion of deserts in the middle latitudes of the Northern Hemisphere (Taklamakan is the second largest sand sea on Earth), knowledge of these sand seas' past changes is important for understanding climatic changes in the terrestrial regions of mid-latitudes.