SPATIAL AND TEMPORAL CHARACTERISTICS OF LANDSLIDES AND THERE RESPONSE TO CLIMATIC CHANGE FROM SIGOU TO LAGAN GORGES IN UPPER REACHES OF YELLOW RIVER

Landslides forming dynamic mechanism and their response to the global climatic change are becoming a hot and focus issue in geological disasters research. This paper is based on paleo-climate evolution, the evolution of the Yellow River and the chronology of some landslides. It studies typical landslides from Sigou gorge to Lagan gorge in the upper reaches of the Yellow River, where is one geo-hazard high-prone zoning area in China. The spatial and temporal distribution characteristics of the massive landslides and the giant landslides are summarized. The relationship between landslide development periods and the response of landslides to the global climatic change are also analyzed. On the basis of above study, the authors discuss the dynamic mechanism of landslide development and the climate change. They believe that the ancient and old landslides mainly occurred in the warmly and humidly periods and the rapid climate change transition stages. The results of this research are as follows.(1)the landslides of the studied areas distributed widely and led severe geological disasters, particularly in the Qunke-Jianzha Basin. The dynamic mechanism of landslides is very complicated.(2)With dating samples of slip zone of landslides and studying the relation between a landslide and its overlying or under-covering loess formation, the chronology sequence of landslides is established. Five stages of landslide development are divided, i.e.53～49ka B.P.、33～24ka B.P.、10～8ka B.P.、5～3.5ka B.P. and present.(3)the landslides developmental stages are closely corresponds to warm and wet stages over the last 100ka, i.e. ,the two weak paleosol-developed stages of Malan loess of the last glacial period in the Chinese loess Plateau L1-4 and L1-2.They both are belong to the marine oxygen isotope stage 3,the last deglacial period, the Holocene Optimum and the present global warming period.(4)Landslide-triggered drivers may be closely linked to the global climate change. Landslides mainly developed during the warm and wet climatic periods and were related to the rapid climate transitions.