The Structure Characteristics and Coal-Accumulating Features Under Sequence Framework in the Late Triassic of Qiangtang Basin

Based on the geological data in recent years,by discussing the structural attribute,geodynamic mechanism,structural evolution course of the south and north boundary structural belts of Qiangtang Basin,we analyzed the evolution and structural attributes in the late Triassic of Qiangtang Basin.On the basis of researching the Upper Triassic lithology,lithofacies in different locations within the basin,we established sequence stratigraphic framework in the Upper Triassic by Identifying Sequence interface and systems tract interface under the different ancient geographical backg rounds,and discussed the location of coal-bed in the sequence stratig raphic framework,the coal accumulation characteristics and spatial distribution law.The results show that the Qiangtang basin was a complex superposition basin in the Upper Triassic,and experienced the passive continental margin basin at the early and mid-stage in Late Tr iassic,the Foreland Basin in the northern Qiangt ang and the passive continental margin rifting depression basin in the southern Qiangtang at the late-stage in Late Triassic.The coalbed was located in the middle-upside of the highstand systems tract,which was mainly controlled by high-frequency and lowgrade sea-level changes.