EVALUATION AND MODELS OF CENOZOIC SEDIMENTATION IN THE SOUTH CHINA SEA

The South China Sea is a marginal basin with the most complex geological structures in the west Pacific region and is characterized by the extensive distribution, large thickness, diversity and complicated evolution of the Cenozoic sediments. The author believes that studies of the sedimentary features and evolution of the Cenozoic are fundamental to understanding the Cenozoic evolution of the South China Sea, and that the definition of sedimentation models will be helpful in inferring the basin development at early stages, thus defining the basin patterns and guiding hydrocarbon exploration. This article, based on data obtained from hydrocarbon exploration in the South China Sea, together with related references, analyses the characteristics of Cenozoic sediments in the South China Sea and infers their evolution and models of formation. The Cenozoic in the South China Sea is divided into eight sedimentary provinces. A brief introduction is given to changes in sedimentary environments of the South China Sea during the Eocene, Late Oligocene-Early Miocene, Middle-Late Miocene and Pliocene-Quaternary. The line linking Taiwan and Natuna, as this article points out, was the sea-land boundary of the South China Sea in the early Cenozoic. The transgression cycle is dominant west of this line, while regression prevails to the east. During the Cenozoic, five different patterns of sedimentation existed in the South China Sea: offshore lake, shallow sea-deep sea, transgression, regression and platform. The former two belong to the lower cycle, whilst the latter three to the upper cycle. The time and spatial variations in the sedimentary sequence of these patterns is also discussed.