CENOZOIC SUBSIDENCE HISTORY OF THE PEARL RIVER MOUTH BASIN, NORTHERN SOUTH CHINA SEA

Pearl River Mouth Basin is the largest basin in the northern continental margin of the South China Sea. In order to study the its subsidence characteristics, temporal–spatial variation, and controlling factors, we have calculated and mapped 34 wells' subsidence via 1‐D backstripping method, from which 12 typical wells have been selected as a sample to compare. Three typical profiles also have been chosen to compile subsidence evolution profiles by 2‐D backstripping method. All wells were synthesized as the holistic subsidence of the whole basin. The results indicate that the holistic subsidence of the basin can be divided into three episodes: The first one was Eocene with the mean total subsidence rate of 85 m/Ma; the second episode was from Oligocene to Middle Miocene with the mean total subsidence rate of 146 m/Ma; and the third episode was from Late Miocene up to present, and its mean total subsidence rate was 104 m/Ma. It is a common phenomenon that variation of subsidence and evolution existing in different units during the same period as well as different periods in the same unit. According to the distribution of subsidence rate in the plane, the basin can be divided into three zones from east to west, and several belts in the same zone from north to south during each period. The variant change of subsidence evolution is related to the phase of basin evolution and structural characteristics. The holistic subsidence of the whole basin is controlled by basin dynamics, and the temporal–spatial variation of subsidence is affected by both basin dynamics and structural framework.