The Research Of The Shale Group Of Lower Cambrian Maidiping Formation And Qingzhusi Formation In Southwestern Sichuan Basin

Knowing the characteristics of the shale group of Maidiping-Qingzhusi Formation in Southwest of Sichuan Basin, and through systematically researching the lithology, the organic geochemical features, the Inorganic chemical features, the mineral assemblage characteristics, the Porosity and adsorption characteristics of which, we worked out the main controlling factors of porosity and adsorption capacity of shale.The main outcome is as followed:1) Within being thick, the shale group of Maidiping-Qingzhusi Formation in Southwest of Sichuan Basin is widely-distributed. The main lithology of which is shale and siltstone, the Qiongzhusi Formation is belonged to the Lower Cambrian Series along with the Maidiping Formation, therefore, it is been called the shale group.2) Vertically the condition of the organic matter of Qiongzhusi Formation is much better than Maidiping Formation, while horizontally which in the east part of Mianyang-changning intracratonic sag is better than other part of it.3) The data analist of the west side of the intracratonic sag shows its tendency of poor-oxygen sedimentary environment, while the middle and the east part of the intracratonic sag is anoxic environment. Based on the geochemical data and the slices analysis, we consider that the main reason of the siliceous sediments of the two formantion is biochemical effection, but not hydrothermal cause.4) The main minerals of the rocks of the two formations are Quartz and clay, meanwhile the feldspar and the clay are genetically connected.5) The Specific surface area experiment data of the selected rock samples indicates that morphologically there are two kinds of pores and there are three kinds of pore based on the pore size distribution curve. The inkpot-type and the multiple-peaked-A type point to the same type of pore, which is full of organic matter and has a good development of pores.6) The main determinant of the Maidinping-qiongzhusi Formantion is the organic matter, but not other factors, such as the clay.7) The main controlling tectonization is Xinkai tafrogeny, during which the Tongwan movement Leads some specific local uplift, meanwhile the two period of regression-transgression after Simian provide the background of the sedimentation.