Southern Sichuan The Triassic Jialing Group Structural Analysis

Under the guidance of new theories and methods of Structural Geology and structural analytical technology including Structural Geometry, Structural Kinematics and Structural stress, this thesis has discussed the general characteristics of structural styles in South Sichuan Basin and put forward the zoning of such styles. Characteristics of each zoning have been analyzed, and structural origin patterns for the different zoning have been produced. To be more clearly, some important structures have been selected and analyzed structurally. The results have further proved the characteristics and patterns of the zonings. According to the study achievements of each zoning, the structural cause has been derived out clearly and reasonably and the pattern maps of such cause have also been established. Based on the study, the relationship between structural styles of South Sichuan Basin and oil and gas has been discussed. The main conclusions drawn in this study are as following:1. The occurrence of South Sichuan Basin structure depends mainly on two stages of structures, that's, nearly east-westward structures caused by nearly south-northward structural extrusion during Yanshan movement and nearly south-northward structures caused by nearly east-westward structural extrusion during Himalayan movement.2. In the east part of South Sichuan Basin, structures are mainly controlled by the Himalayan movement. The relative highest intensity of structural compression occurred in the middle pare of Huaying Mountain fracture belts and the intensity decreases gradually toward the two sides of south and north. The two stages of structural movements in the south have more obvious effects. The east-westward structures are first formed and overprinted by nearly south-northward structures. Meanwhile, such nearly south-northward structures as Guandu and so forth are produced. The direction of the two stages of structures are perpendicular each other. Structures in the north- west part are mainly developed during the extruding period nearly north- southward. Because of the existence of Huaying Mountain fracture belt and the oblique intersection between the direction of such belt and the regional major effort, special double- en echelon folds were formed in the area. In the middle part, amplitude of structural folds is low because of the relative weaker intensity of structural effort. Tectonics styles of this area are more complex in that two stages of structural movements were overprinted. Fractures, however, are still well developed.3. It has been pointed out in this article that the oil and gas in South Sichuan Basin have rimmed- triangle distribution. The fractures are developed in the margin areas while have a bad reserve. The middle part of the study area shows a good development of fractures and reserve condition, therefore can be thought of as important and favorable targets for exploration and development.