论泥石流沉积与环境

DISCUSSION ON SEDIMENTARY ENVIRONMENT AND DEBRIS FLOW DEPOSITS

甘肃武都地区及陕西某些地区典型泥石流沉积剖面,可分为A,B,C,D,A′5种相。不同的相组合,剖面沉积特征及纵、横剖面等,都从不同的角度较好地记录了环境变化。

Ancient environment rebuilding is a very trouble problem for many years. After studying the standard debris flow deposit in different area,the relationship between the different facies,facies associations, sedimentary feature of section, vertical and cross section,and depositional environment is discussed in this paper.Debris flow deposit can be separated into A,B,C,D,and A' 5 different facics. The facies of A,B,D,A1 represent the period of debris flow deposit.and the C facies stand for times of depositional interruption. Research on B facies should be given more attention in the fieid, which also can give the information about time of the depositional interruption according to whether it contain the fossil of aninalsand plants. Different facies associations reflect the depositional features of debris flow in different environment. From southwest to northeast in China the C facies increases in facies associations gradually.This represents that frequency of debris .flow activity decreases and the climate changes from wet-hot to dry-cold.Sedimentary section of debris flow reflects quite the paleoclimatic.change.At .period of debris flow deposit during late Pleistocene, the climate had three middle scale changes in Wudu Region, Gansu Province. The comprehensive records of environment change which showed by cross and vertical section of debris flow are different. The vertical section can give more information about sedimentary environment. The change of thickness in section records the change of debris flow supplying quantity and accumulate quantity in material source area. The deposit and interrupt of debris flow respect the climatic change in the region, they are the record of environment change.