云南星云湖断陷湖盆中粘土矿物组合特征与沉积环境关系的初步探讨

于１９８８年对云南星云湖盆地区进行调查，运用Ｘ射线衍射，差热分析，红外光谱分析和扫描电镜方法，对该盆地的第四系泥岩和现代沉积环境的泥质沉积物的４９个样品进行研究。发现，现代环境中粘土矿物分布规律明显，且与第四系沉积物有对比性，从而推断盆地沉积环境分布和演化与泥质沉积物的微量元素聚类分析结果相吻合。

A PRELIMINARY STUDY ON THE RELATIONSHIP BETWEEN THE CHARACTERISTICS OF CLAY MINERAL ASSEMBLAGE AND SEDIMENTARY ENVIRONMENTS IN DOWN-FAULTED LAKE BASINS OF XINGYUN LAKE, YUNNAN PROVINCE

Xingyun Lake located in the eastern part of Yunnan Province is a down-faulted basin with an area of 38.1km², maxium depth of 11.3 m, and mean depth of 7 m. X-ray differaction analysis, differential thermal curves analysis, and infrared absorption spectrum analysis of 49 samples investigated in 1988 showed that the main clay minerals in the modern and Quaternaryi sediments of the Xingyun Lake are illite, montm-orillonite, kaolinite and chlorite. They are distributed in different depositional facies in delta front environment. Illite and kaolinite appear in fluvial deposits, while montmorillonite is rich in shallow lake sediments. From the margin to the center of the lake basin, the content of illite and kaolinite decreases, while the content of montmorillonite and chlorite increases. The mainclay mineral assemblages in Quarternary sediments are:

(1) Lower assemblage: M (montmorillonite) -I(illite) -K(kaoliniteQ->CH(chlorite);

(2) Middle assemblage: I-K-CH;

(3) Upper assemblage: I-M-K.

The sedimentary environment reconstructed according to the characteristics of the clay minerals concords with the results obtained by analyses of trace elements, fossils, sedimentary structure and vertical sequence, etc.