冰碛转化为冰川泥石流堆积过程及其沉积特征

Process of Accumulation and Characteristics of Glacial Debris Flow Deposits Trangformed by Moraine

冰碛与冰川泥石流堆积同是冰冻圈内的两种混杂堆积，前者是后者的物质来源，后者又是前者的再生沉积，在沉积特征上既有相同处，又有相异点。本文阐述厂由冰碛向冰川泥石流堆积的转化过程，并遵循多指标综合原则，提出了依据沉积构造、砾石组构、沉积韵律、粒度特征、石英砂表面结构、粒序垂向变化等１０项区分二者的判别标志。

Moraine and accumulaion of glacial debris flow are two kinds of mixed depOSits within the cryosphere of the earth's surface. Moraine is a material source of glacial debris flow and accumulation of glacial debris flow is a new mixed deposit transported and transformed by glacial debris flow. Both appear similar, but differ in sedimentary characteristics. It is very important for understanding of cause and type on mixed deposits in the cryosphere and evolution of natural environments to verify both sedimentary characteristics and process that moraine transforms into accumulation of glacial debris flow.By effect of erosion of melting water and earthquake, moraine may block up a channel.As air temperature rises rapidly and glaciers and snow melt obviously, melted flood has to be obstructed by blocked moraine in the channel and to form a lake. Blocked material soon bursts out in action of flow pressure. Outburst floods are able to transport sediments in the form of drawing and bed loads and to transform them into glacial debris flow with either moving flow of viscidity or dilute turbulent flow. At last, glacial debris flow can form accumulative fan or cone in a gentle area. The above content is the basic process that moraine transforms into accumulation of glacial debris flow.After deposits of moraine and glacial debris flow are studied and compared in detail, both mutiple identified indexes have been set up, in which there are common indexes of mixed deposits as well as some distinctive indexes for each one. The distinctive indexes include sedimentary bedding, sedimentary structure, sedimentary rhythm, gravel fabric, size features, vertical change of size sequence and surface features of quartz sand, etc.. With practical test, it is found that the above study method and the indexes that identifiy glacial debris flow and moraine are feasible and reliable.