| The Upper Permian-Lower Triassic (P2-T1) sequence can be classified into one whole long-term base-level cycle（LC1） by using the high-resolution sequence stratigraphy and the base-level cycle recognition technology, and referring to the regional tectonic cycles and sea level changes in Lower Yangtze area. Based on the drilling data in the South Yellow Sea, five medium-term base-level cycles (MC1 to MC5) are recognized in LC1. The analysis of well-linking correlation has shown that delta, tidal flat and shelf facies commonly develop in P2-T1 strata, and sedimentary waters is deeper in the northwest than in the southeast. In the light of integrated analysis of changing base-level cycles and sedimentary environments, two filling patterns of base-level cycles can be recognized in the Upper Permian-Lower Triassic sequence, one is the stable Upper Permian Longtan tidal flat facies and the other is the rapidly-transgressive Upper Permian Dalong shelf facies to stable Lower Triassic Qinglong platform facies. These patterns will be significant to petroleum geology evaluation to Mesozoic and Palaeozoic marine sediments in the South Yellow Sea Basin. |
