青藏高原风化壳红土的沉积地球化学和矿物学特征及环境意义

对青藏高原主夷平面上分布的风化壳红土进行了沉积地球化学和矿物学方面的研究。结果表明，高原风化壳红土中细粒物质（粒径小于１ｍｍ）的粒径分布范围较广且比较均匀；红土中粘粒部分的主要化学成分为ＳｉＯ２，Ａｌ２Ｏ３和Ｆｅ２Ｏ３；粘土矿物多属于伊利石－高岭石型组合，少数属高岭石－伊利石型组合。高原风化壳红土处在红土化的初期阶段，间接反映了青藏高原古岩溶发育时期的湿热气候。

The Sedimentary Geochemistry and Mineral Characteristics and Environmental Significance of the Laterites on Plateau of Tibet

It was observed that the relative deposits of the Tertiary palaeokarst, i e , limestone residual laterite, are widely distributed on the main planation surface of Plateau of Tibet. The frequency distribution curves of the finer grains in those residual laterites are relatively even and wide, expecpt for some samples which have one or more peaks.SiO\-2, Al\-2O\-3 and Fe\-2O\-3 are three main parts in the clay minerals.The clay mineral compositions mainly belong to illite\|kaolinite type,while a few samples are the kaolinite\|illite types.Judged by the silica\|allumina ratio and the clay mineral composition, the residual laterites reflect a kind of preliminary laterization processes However, considering the vertical distribution of weathering degree in the weathering section, those residual laterites still reflect a kind of humid and hot climate, i e , a kind of tropical or subtropical climate.