• 责任者：Yin Zhiqiang (China Institute of Geo-Environment Monitoring ; Beijing 100081 ; China) ; Qin Xiaoguang
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(5)
• 关键词：红粘土 ; red clay ; 泥石流 ; debris flows ; 青藏高原 ; Qinghai-Tibetan Plateau
• 页码：p.995-1004
• 图表：9 illus., 3 tables, 44 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     The destruction reasons of Lajia prehistoric disaster relics in Guanting basin is a hot and focus issue in recent years.In this paper,based on the results of field investigation analysis and laboratory tests,the deposition sources,formation mechanism of red clay layer,which lies in the second terrace of the Yellow River of Guanting basin has been explored.The authors revealed that the huge impact of the debris flow to the Lajia prehistoric disaster relics,this result will provide some geological basis of disasters prevention and mitigation in some mountainous area neighborhoods.The results of this research were：1）The depth of red clay layer profile is 2.45m in Guanting basin,the grain size distribution characteristics of red clay layer can divide into three components and the second is the dominant,which median grain size is 9~11μm; magnetic susceptibility values of the red clay profile are mainly distributed between 20×10-8~40×10-8 m3/kg; 2）The obviously differences of developmental age,color,grain size distribution characteristics,magnetic susceptibility,soil structural parameters between the red clay layer profile of Guanting basin and lake sediments of Jishixia valley,which reflected that different formation mechanism between them,and the red clay sediments has unrelated with the dammed lake outburst of Jishixia valley; 3）Due to earthquake or tectonic activity,some ancient landslides and mountainous collapses were formed,on the other hand,the Tertiary loose clay materials of north side of hillside of Guanting basin were all closely scour handling accumulation in the piedmont sloping sites by the heavy precipitation,the destroyed flooding of Lajia disaster relics came from some valleys of north hillsides,eg：Gang valley.Therefore,the flooding was not from the upper reaches of Yellow River; 4）The forming mechanism of the red clay layer of Guanting basin may be：earthquake-induced landslides and collapses,at the same time,the mountainous loosely.Then,the deposits of landslides and collapses and the mountainous loose material were carried to exports of valley and the lower second terrace of the Yellow River along the valley by the heavy rain or sustained rainfall.Therefore,the debris flows induced by the flushing flood after earthquake was the actually reason of destruction of the Lajia disaster relics.