Case Studies On The Formation And Diagenetic Evolution Of Montmorillonite

Clay minerals are very abundant in China and regarded as important mineral resources. In addition to be essential for industry, clay minerals have significant importance in geological science. By investigating the characteristics and compositions of clay minerals, we can conclude both the distribution and the source of minerals. Furthermore, the analysis of clay minerals also plays a great role in many areas, such as palaeogeothermal reconstruction, paleoclimate research, stratigraphic classification and petroleum exploration. Based on the basic theory of clay minerals, the diagenesis of clay minerals and their characteristics were illustrated in this paper. In order to elucidate the two topics which are the formation and the diagenetic evolution of clay minerals, the clay minerals were selected from the bentonite belt located in riverside area of Jiangsu and the main reservoir of Shengli Oil Field respectively. After sampling, processing and analyzing, the data of clay minerals from Dongying sag were discussed. According to the images captured by scanning electron microscope (SEM), the clay minerals in Dongying sag contains kaolinite and chlorite; By the X-ray diffraction analysis, these clay minerals are primarily consisted of kaolinite, followed by illite and chlorite, and montmorillonite is rarely contained.This paper reports a study on the characteristics of the bentonite deposit in Jiashan, Jurong City of Jiangsu Province. The layered ore is located in the andesite and andesite-prophyrite of lower Cretaceous. The ore present various colors, such as yellowish green, pink, light gray and pinkish color. The remained breccias structure or residue lumps of primary volcanic rock can be observed. On the sliding surface of the faults, the sub-roundstone breccias are found. X-ray diffraction analysis indicates that the mineral composition varies with the color. In the images of scanning electronic microscope present the weathering of primary and secondary minerals in the ore and volcanic rocks. In summary, this deposit belongs to weathered residual bentonite deposit. It is think that classification in ore development and deep processing can improve the economic effectiveness.