The present paper deals with the evolution of the palaeoclimatic conditions of the Mawo karst basin in Weining, Guizhou on the basis of composition, content, crystallinity index, chemical index and relative content of the clay minerals by using the X-ray diffraction analysis. The clay minerals in the study area are composed dominantly of mixed illite-montmorillonite layers (30% -75%) and chlorite (10% -45%) , and subordinately of gaolinite ( 5% - 20%) and illite ( 10%) with no montmorillonite, and derived from the weathering of the surrounding bedrocks. Four stages are recognized for the evolution of the palaeoclimatic conditions in the study area, including three major climatic cycles and several minor climatic cycles.%利用X射线衍射等分析方法,对贵州威宁麻窝山岩溶盆地沉积物中粘土矿物进行研究,获得了粘土矿物的组成、相对含量、结晶度指数、化学指数以及相对含量比值等方面的信息,探讨该盆地的沉积环境演化特征.研究表明,粘土矿物以伊/蒙混层矿物(30%~75%)和绿泥石(10%~45%)为主,高岭石(5%~20%)和伊利石(10%)次之,基本不含蒙脱石.伊/蒙混层矿物和绿泥石含量呈负相关性.高岭石含量在剖面底部较稳定,在484cm上部出现较大的波动.伊利石结晶度和化学指数与伊/蒙混层矿物含量具有较好的正相关性,且在第Ⅰ阶段相对于其它指标较敏感,出现波动.通过综合对比分析,将研究区剖面划分为4个阶段,其是3个冷暖干湿的大循环和若干个小循环气候环境的物质记录.
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