Characteristics And Original Analysis Of The Clay Minerals Of Jurassic In Turpan Depression

This paper detailedly analysis the origin and characteristics of the clay minerals of the Jurassic rocks from the Turpan Depression, using traditional research methods, combined with more advanced environmental scanning electron spectrometer instrument and energy spectrometer. The detailed study results show that:(1) The main component in Turpan Depression of Jurassic is SiO2, Al2O3, followed by S, the SiO2 is the lowest in Xishanyao formation,the reason is that part of SiO2 in the upper layer Xishanyao formation was dissolved, while it was well-preserved in the lower layer of Sangonghe formation and Badaowan formation; The A12O3 content is the highest in the upper layer, it decrease,while the burial depth increases, reflecting the degree of clay rocks in Turpan Depression is almost consistent with the degree of oxidation of rock.(2) Jurassic Turpan Depression of clay minerals in each formation was formed in diagenetic stage, the mainly clay minerals is kaolinite and illite, followed by smectite and chlorite, the rock formation wsa in the acidic environment, it buried not very deep.The clay mineral content is the highest in the upper layer of Xishanyao formation, it is clear that the clay mineral content decreases from Xishanyao to Sangonghe and Badaowan formation. It mainly occurred kaolinization, illitization, smectitzation and chloritzation and so on. Montmorillonite and kaolinite content is related to the alteration of clay minerals and the epigenetic process of conversion. It depends on temperature and groundwater conditions.(3) The smectite in environmental scanning electron microscope is a collection of multi-form and varied shapes. A similar sponge-like, spherical aggregates, is often around the particles, there are flaky smectite, honeycomb-like smectite. Kaolinite is mostly smaller aggregates, and there are worm-like shape, but also the organ-like aggregates,it is often in the form of pore filling between the particle or in the surface. Illite is mainly feathery aggregates, also observed irregular illite/Montmorillonite mixed layer, some illite displayed the characteristics of the form to transformed montmorillonite. Highly sophisticated early kaolinite is formed by K, Na, Ca, Mg and Si-Al-oxide colloidal precipitation due to weathering under acidic conditions.The formation of smectite have the relatationship to topography, climate, and groundwater conditions of burial condition,it is transformed from feldspar, mica and other clay minerals under magnesium-rich dried alkaline conditions.(4)The clay minerals in Jurassic mainly is Ca, Mg, Al, U, Ti, V, Fe, Re, it is exist in the kaolinite, smectite and illite by adsorption. but smectite can adsorb more C and metal ions than the kaolinite.