TECTONIC CHARACTERISTICS OF NORTHWESTSUBBASIN AND SEAFLOOR SPREADING HISTORYOF SOUTH CHINA SEA IN CENOZOIC
Yao Bochu;( Guangzhou .Marine Geological Survey, MLR Guangzhou 510075)
By analyzing the topography, landform, gravity anomalies, geomagneticanomalies and crustal structure, and interpreting the seismic profile across theNorthwest Subbasin and the Central Basin, it is found that the trends of geophysicalanomalies, geological structure and crustal isopach are to the northeast in theNorthwest Subbasin. and to the east in the Central Basin. The Northwest Subbasin hasone more set of strata (T4-Tg) than the Central Basin, which means that the age ofthe Northwest Subbasin is older than the Central Basin. According to the similaritiesin the regional structure, geophysical anomalies, topography and landform, and the agedifference between the Southwest Subbasin and the Central Basin acquired byinterpreting magnetic anomaly lineations, it is believed that the Northwest Subbasinand the Southwest Subbasin formed during the firet seafloor spreading between the lateEocene and the early Oligocene (42-35 million yrs. B. P.), and the Central Basinformed during the second seafloor spreading between the late Oligocene and the earlyMiocene (32-17 million yrs. B. P.).
【CateGory Index】： P736.1