Tectonic And Sedimentary Evolution Of Triassic Southern Qilian Basin

South Qilian basin is located in the northeastern margin of Qinghai-Tibet Plateau, the north adjacent to widely developed Precambrian of the middle Qilian and development of Paleozoic of the North Qilian Mountains, south adjacent to Zongwulong Mountain-Qinghai Nanshan. Because of the rich geological phenomena and exposed condition Southern Qilian area has long been a classic for the study of orogenic areas. But for a long time, the area of research has always been focused on the evolution of orogenic base, structure and ocean-continent collision process for the Indo-cycle features of the original basin, the superposition between the Triassic basins relationship has not yet been systematically studied. This study therefore a clear understanding of the Triassic Basin, southern Qilian basin during the transformation between the prototype and the superposition of space-time structure of great significance.Using the principles of continental dynamics and basin analysis theory, comprehensive utilization of Geological studies have been, geophysical methods, by means of satellite remote sensing, geological survey combined with field and laboratory research, Through the preparation of southern Qilian basin filling model diagram, Early to Middle Triassic, Late Triassic tectonic pattern map, Triassic basin evolution model map to reproduce the South Qilian basin sedimentary and tectonic evolution of the Triassic.The results show that:the South Qilian area Triassic sedimentary and tectonic evolution can be divided into early and middle Triassic epicontinental sea and Late Triassic delta two-stage regression. Early and Middle Triassic sea water intrusion from the southeast to the northwest, the formation of early Middle Triassic epicontinental shallow sea, in the late Triassic to early indosinian movement, so that the relative uplift of the South Qilian area, the sea retreated from west to east, Basically ancient sedimentary pattern of the south sea and north land. Late Triassic, the overall completion sea basin to land basin of the South Qilian's conversion. The Late Triassic indosinian movement, and ultimately the end of the Triassic basin formation of the South Qilian history, uplift the area as a source area.