广西东攀剖面二叠系顶部粘土矿物特征及古气候意义

Characteristics of Clay Minerals from the Uppermost Permian in Dongpan Section,Guangxi Province and Its Significance

对广西东攀剖面二叠系顶部20个样品中的粘土矿物进行X射线衍射分析。伊利石结晶度值显示这些样品形成于中晚成岩带的地质环境;伊利石、蒙脱石纵向分布规律和伊利石结晶度与伊利石含量的关系表明伊利石除陆源碎屑来源外,可能有部分为蒙脱石伊利石化而成;伊利石结晶度变化曲线和伊蒙混层类型的变化规律表明,本区粘土矿物组合与含量的变化除受到后期成岩作用的影响外,还明显地受沉积因素的控制;伊利石结晶度、伊利石化学指数、高岭石和伊利石的含量、伊蒙混层类型显示东攀剖面以9、10层界线上方5cm为界,古气候由干冷变为湿暖;水介质由偏碱性向酸性转变。

The integrated information of clay minerals from the Uppermost Permian sediments in the Dongpan Section, Guangxi province is measured by the analyses of the X-ray diffraction. Illite crystallinity show that the illite in Bed 9 and Bed 10 is formed in the middle-late diagenetic stage ; Vertical distribution of the illite, smectite and the relationship between the contents of illite and illite crystallinity indicate besides terrigenous clast genesis, part of it may derived from smectite. But the clay mineral assemblages and contents are not only related to the diagenesis, also controlled by the sedimentary factors, such as source rock, climate and geography. Illite crystallinity, illite chemical index, the contents of illite and kaolinite, illite-smectite mixed-layers type show that Paleoclimate turn dry and cold into wet and warm and that water medium turn from alkaline to acidic upward 5cm from Beds 9 and 10 boundary.