Development of Paleogene Depressions and Deposition of Lacustrine Source Rocks in the Pearl River Mouth Basin, Northern Margin of the South China Sea

A more accurate, integrated chronostratigraphic framework is applied to the analysis of the development of Paleogene depressions in the Pearl River Mouth basin. The results of our study show that the development of these depressions was characterized by at least three rifting or basin-forming phases occurring during these periods: late Paleocene (Late Cretaceous?)-middle Eocene, late Eocene-early Oligocene, and middle Oligocene-late Oligocene. The transition from rifting stage to postrifting stage in the basin is about 10 m.y. later than the initial spreading of the South China Sea. The prologue of the spreading of the South China Sea began as early as the end of the middle Eocene. Lacustrine source rocks deposited during the basins first rifting phase are thick and of go d quality; source rocks deposited during the last two phases, which had a sharp increase in sedimentation rate, are of lesser quality, with the exception being those areas where deposits were out of reach of sediment from the northern mainland.