Sedimentary records of holocene palaeo-mudflow events in Tianshui basin of the western Loess Plateau, China

摘要

During our field investigations, a Holocene aeolian loess-soil profile containing three units of palaeo-mudflow deposits is identified in Tianshui basin of the western Loess Plateau, China. Through field observation and the analysis of particle-size characteristics, three palaeo-mudflow deposit layers are differentiated from the interbedding aeolian loess and soil, and they record three episodes of palaeo-mudflow events. Based on stratigraphic correlation, OSL dates and archeological constraints, the three episodes of palaeo-mudflow events are estimated to occur in 7000-6000, 5500-4800, and 4200-4000 yr BP, respectively. Comparison of the ages of the three paleo-mudflow events with the paleoclimatic proxy data from different regions indicates that these three episodes of palaeo-mudflow events were most likely associated with the climatic instabilities and prehistorical human activities. The results of our study, as well as the results of other studies, may provide further insights into the Holocene climate change and also into the prehistoric human activities in environmentally sensitive areas.