Late Quaternary palaeolake levels in Tengger Desert, NW China

摘要

Comprehensive field investigations and laboratory analyses show that palaeolakes, including the Megalake Tengger, and other semi-connected and isolated water bodies, during late Pleistocene covered an area of more than 20,000 km~2. This is an area more than half the size of the Tengger Desert in NW China. Stratigraphic correlations and chronological evidence indicate that the palaeolakes started to develop around 42,000 14C year BP (uncalibrated, all throughout the paper) but their extent was limited until 37,000 14C year BP. Based on the chronology of representative lacustrine deposits, it can be deduced that the Megalake Tengger was established around 35,000 14C year BP and maintained until 22,000 14C year BP, leading to the formation of the Baijian Hu terraces, which are regarded as firm evidence of the existence of palaeolakes. The formation mechanism is unclear and the climate situation at the time is still an open question. The Holocene palaeolakes started to develop around 12,000 14C year BP. The Baijian Hu terraces indicate that the high water levels in the area occurred around 8500, 5400–5100, 3500, and 1860–1370 14C year BP. The extent of the Holocene palaeolakes, primarily migratory lakes, was smaller than that of the Late Pleistocene palaeolakes.