Vicissitude of Cenozoic carbonate platforms in the South China Sea:Sedimentation in semi-closed marginal seas

Cenozoic carbonate platforms are widely distributed in the South China Sea. They are characterized by large thickness and strong spatio-temporal variations. This study summarized most of the recently published findings on the geological and geophysical features of the South China Sea. It is found that all these carbonate platforms have experienced a progressive evolution from initiation, extension, flourishing, drowning and relict stages. Most of them are drowned in Late Cenozoic, and often called drowned carbonate platforms by some researchers. The carbonate platforms are unique in the South China Sea and contain rich information on tectonic evolution. The development of carbonate platforms follows the rifting process. They are usually initiated on the high shoulders of a faulted block at the conjugated rifting margin in Eocene and Early Oligocene. By rifting, thinning, and mantle exhumation of the South China Sea margin, the carbonate platforms has kept growing as NE-SW direction ridges, and flourished till Late Early Miocene. Tectonic subsidence provided accommodation space for platform growth. Tectonic tilt, faulting and migration of compressive folds in the front of foreland basins controlled the distribution of thickness and lateral variation in seismic reflection features. Tectonic induced relative sea level change controlled the sedimentary cycles of carbonate platforms in different orders. Furthermore, the rapid subsidence in Late Miocene and the formation of the semi-closed marginal sea caused the drowning of most carbonate platforms. Only a few carbonate platforms might leave behind as isolated platforms with limited distribution and small scale up to present.