ANALYSIS ON THE UPPER DEVONIAN-TRIASSIC SEQUENCE STRATIGRAPHY IN THE TARIM BASIN AND ITS CONTROLLING FACTORS

The Devonian-Triassic stratigraphic sequences in the Tarim Basin can be divided into two megasequences, five supersequences and twelve sequences. The Late Devonian-Triassic regional geotectonic evolution underwent the local splitting and rematching of "the paleo-Xinjiang plate", and the Tarim Basin involved the Late Devonian-Early Permian back-arc rift and the Late Permian-Triassic foreland basin two stages. The megasequence Ⅰ is the product of the back-arc rift evolutionary stage, in which the supersequence Ⅰ_A represents the deposit of downwarped basins in the craton and the supersequence Ⅰ_B represents the basin-filling deposit of rift in the bacd-arc craton. The megasequence Ⅱ is the deposit of the foreland basin evolutionary stage, in which the supersequence Ⅱ_A represents the filled deposit of peripheral foreland basins and the supersequence Ⅱ_B adn Ⅱ_C are the deposit of inland downwarped basins. Research reveals that tectonic process played a decisive role in the formation of most Ⅲ-order sequences. Only in the evolutionary period of the Late Devonian-Carboniferous passive continental marginal and craton basins, during which tectonics are relatively stable, did the global eustacy act a greater part in the formation of the sequences.