ANALYSIS OF CENOZOIC ABRUPT EVENTS IN CORAL AREAS IN SOUTHERN SOUTH CHINA SEA

In the coral reef area of the southern South China Sea, abrupt events are quite often, which well recorded the changes in tectonic and sedimentary environment. In this paper, we summarized the Cenozoic abrupt events in the research area and discussed their relation with major tectonic abrupt events according to the collected geophysical data and the previous works. Tectonic events vary with tectonic units. For examples, tectonic events in the Zengmu basin were happened in late Cretaceous, late Eocene, late early Miocene, late middle Miocene, late Miocene and late Pliocene respectively, while the events in the Wan' an Basin happed in the Late Cretaceous, early Eocene, early Miocene, Late Miocene and Late Miocene. Since the events in coral reef area are usually regional, they are easy to trace and make correlation. In the basins of the study, there are 3 tectonic events happened respectively in late Cretaceous-early Paleocene, late Eocene and late middle Miocene as the records of the Liyue movement, the Xiwei movement and the Nansha movement. The erosional unconformities saved in the Early Miocene basins reflects the drop of global sea level. However, it is missing in the Beikang Basin due to the Nansha movement. The three unconformities and the erosion recorded the tectonic evolution of the South China Sea.