黄河上游寺沟峡拉干峡段滑坡时空特征及对气候变化的响应研究

滑坡发育动力机制对全球气候变化的响应过程逐渐成为地质灾害研究领域的热点和焦点问题。文章以我国地质灾害高易发区的黄河上游寺沟峡拉干峡段大型、特大型、巨型滑坡为研究对象,在广泛收集区域古气候演化资料和滑坡年代测定的基础上,开展了末次冰期以来特大型、巨型滑坡发育的时空分布规律研究,分析了滑坡的主要发育期与全球气候变化的响应关系,在此基础上探讨了研究区滑坡发育的动力机制对气候变化的响应过程。主要取得了以下认识:(1)研究区滑坡异常发育,分布广泛、成灾规模大、动力机制复杂、危害严重,在空间上以群科尖扎盆地最为发育; (2)利用滑坡钻孔滑带土和滑坡体与上下覆黄土的叠置关系开展了滑坡体的年代学测定工作,并从时间尺度上划分了滑坡的5个主要发育期,其分别为53～49ka B.P.、33～24ka B.P.、10～8ka B.P.、5～3.5ka B.P.和现代; (3)研究区滑坡的主要发育期分别对应于中国黄土高原马兰黄土中的2层弱发育古土壤层L1-4 和L1-2、末次冰期晚期/全新世过渡期、全新世适宜期和现代全球升温期; (4)全球不同地区滑坡的发育期与气候变化有密切联系,其主要发育于古气候的温暖湿润期和气候变化的快速转型期。

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.