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

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.