Debris flow events of 4000 aBPand its resulting archaeological site destruction in Qian River gorge, the upper reach of Wei River, central China

In the study of global change, the relationship between the Holocene climatic disaster events and the rise and fall of ancient civilization is of considerable significance to a profound understanding of civilization evolution and human-land harmony. During the geological survey in the western Wei River Basin, a debris-flow event that would have destroyed an archaeological site was uncovered in the Holocene loesson the south bank of the Qian River. They were studied by field observations and laboratory analysis, including magnetic susceptibility, particle size distribution, carbonate content determination, and AMS(14)C dating. The debris-flow event was dated at about 3702 BP to 4084 cal BP by using the AMS(14)C in combination with archaeological artefacts age determination. Mingling with cultural layer, whole pig bones, and covering ash pit and cellars, the debris flow incident was linked to the site destruction. Combined with the global climate background at about 4000 a BP, the palaeo-floods records in the Wei River Basin, and the regional palaeo-earthquakes, we infer that the debris-flow was triggered by large earthquake and heavy rainfall and was a regional hydrological response to the 4.0 ka global climate event. Moreover, the debris-flow incident and its resulting archaeological site ruin have essential scientific significance for exploring the climate environment evolution, the ancient civilization evolvement, and the human-land relationship development in the Wei River Basin and surrounding area.