晚更新世小江流域泥石流沉积特征及发育规律

Deposit Characteristic and Developed Law of Debris Flow During the Late Pleistocene in Xiaojiang Valley

泥石流沉积物作为晚更新世一种特殊沉积类型,是在特定的地质过程和地理环境中形成的。由于特殊的地理环境,泥石流沉积成为晚更新世小江流域主要的沉积类型,本文在研究了青藏高原东缘小江流域蒋家沟附近晚更新世不同时段泥石流沉积剖面沉积特征、化学元素及可溶盐成分的富集规律、CaCO3含量、pH值、有机质含量及植物花粉组合特征后发现,自末次间冰期到末次冰期,沉积物基质中可溶性盐在增多,花粉从以木本为主转变为草本为主,同时泥石流沉积层有变薄的趋势,反映了随气候变冷,泥石流有减少的趋势。

As a special deposit type,debris flow deposit forms in specifically geological structure and geographical environment.Because of specifically geographical environment,debris flow deposit becomes the main deposit type in Xiaojiang Valley.On basis of studying deposit characteristic,the law of distribution,assignation,transference and enrichment of chemical element and soluble salt,the content of calcium carbonate,acidity and basicity,the content of organic matter and combination character of plant＇s spore and pollen in deposit section of debris flow during different times of the Late Pleistocene near Jingjia Valley in Xiaojiang Valley in the east border of Tibetan Plateau,and according deposit characteristic of debris flow.This paper finds that since the last interglacial stage to the last glacial period,the soluble salt increased,and the mainly pollen has changed into herbal from woody.At the same time the debris flow deposits are the trend of thinning.This reflects that a cooling tendency of climate caused a decrease in debris flow.