Sequence stratigraphic and evolution of the Ganquan platform in Xisha area, South China Sea

The Ganquan Platform is a typical submerged carbonate platform in the Xisha Island, South China Sea. To unravel the architecture and development of the platform, two-dimensional multi-channel seismic data were collected, and the noise reduction was performed to obtain three high-resolution multi-channel seismic profiles. Ten special seismic facies and 4 sequence boundaries were identified on the seismic section, revealing that a 700 m thick carbonate formation was developed in the Ganquan Platform since the early Miocene, and submerged in the Pliocene.Large amounts of gravity flow deposit and contour flow deposit were developed at lower-bottom slope areas. Sedimentary facies in the slope varied with depth, siliceous-carbonate rock clastics were seen in the bottom of the slope, and carbonate rock clastics in the upper slope. The stratigraphic characteristics of the Ganquan platform and the tectonic background of the Xisha region show that the submerged carbonate platform in the Xisha was born at a structural height during the Late Oligocene to the Early Miocene. In the Middle Miocene, the relative sea level rose steadily and thick carbonate platforms were formed. In the Late Miocene, the relative sea level rose rapidly and the northeast monsoon strengthened, announcing the final stage of the carbonate platforms in evolution. In the Pliocene, the relative sea level increased continuously and rapidly. The reef carbonate platform submerged gradually and perished at last.