Geological environment changes during the late Pleistocene-Holocene on the E'mei tableland in the northern Yuncheng basin, Shanxi Province: Implications for the distribution of human settlements

Neotectonic movements and the changing natural environment have profoundly influenced human settlements on their formation and distribution. The Gushan uplift, Niandi low-lying area and Sanguan highland developed from north to south in the central section of the E'mei tableland; however, human settlements nowadays distribute on the peripheral slopes around the low-lying area rather than right in the Niandi low-lying area. Our field investigation reveals that the Malan loess is overlied by a set of alluvial-diluvial deposits, lacustrine deposits, and fluvial deposits. This paper mainly presents field evidence and chronological analyses of OSL and 14C for the typical sections of different geomorphic sites to discuss the geological environment evolution of the E'mei tableland during the late Pleistocene-Holocene and its influence on the migration of human settlements. Our field investigation and analysis results show that the formation age of the bottom of the late Pleistocene lacustrine deposits above the loess in the Niandi low-lying area is about 17 ka B.P., indicating a depression had developed in the middle section of the E'mei tableland during this period with water converging in, forming a lake afterwards. Combined with the regional structural data, it is speculated that the formation of this depression was caused by the fault activity on the north side of the Sanguan highland. The location of 5000-year-old ruins of Jingcun Village and Yuanjiazhuang Village shows that the lake may have expanded to the piedmont of Gushan in the middle Holocene. Along with increasing dryness of climate and the shrinkage of lake, human settlements kept migrating to the low-lying lands. Nowadays, villages around the periphery of the Niandi low-lying area carries on the distribution pattern of living by water in the middle-late Holocene, which indicates that the distribution and evolution of human settlements are closely connected with the changes of natural environment.