Inversion structures in the northern continental margin of the South China Sea:Taking Lingao Uplift in the Yinggehai Basin and Qionghai Sag in the Pearl River Mouth Basin as examples

To reveal the geometry,evolution and timing of inversion structures on the northern continental margin of the South China Sea,we analyzed the inversion structures in Lingao Uplift of the Yinggehai Basin and Qionghai Sag of the Pearl River Mouth Basin through quantitative analytical methods. Growth index,displacement-distance curve and reversal rate of inversion structures are calculated in above two basins. The results suggested that the tectonic inversion in Lingao Uplift began in the Early-Oligocene,mainly developed from the Late-Oligocene to the Early Miocene,the inversion degree is moderate,and it belongs to fault inversion structures with cap upper part and normal lower part. Tectonic inversion in Qionghai Sag developed in the Late-Miocene,the inversion is mild,and it belongs to folded inversion structures with convex upper part and concave lower part. The inversion structures in the two basins have good hydrocarbon potential in generation,storage,cover and the good relationship between time and space allocation,they are favorable traps for the oil and gas accumulation.