Tectonic Features Of The Basins At The North Margin Of The South China Sea From Cretaceous To Oldest Eogene

The tectonic features of China southeast continental margin are characterized bydivergence and compression, and many Cretaceous-Tertiary basins emerged in thisbackground. The tectonic course of these basins has close relationships withmovement of Pacific plate and the Eurasian plate, may also the evolution of theProto-South China Sea and the South China Sea（the SCS）.（1）There is a continental marginal arc that on behalf of the proto-SCSsubduction in the north of the SCS. All basin that keep volcanic-sedimentary recordsare associated with continental margin arc. It indicates that the reaserch area has aepicontinental arc system that includes many Andean type of basin and the width hasmore than600km, the system of distribution is given priority to with the north-southdirection.（2）The internal history evolution of the epicontinental arc system aredifferent. The magmatic, sedimentary or tectonic features of near arc region, Ledong,Maoming, Sanshui Basin, are showed a close correlation with the pressureenvironment of epicontinental arc in the most of Cretaceous; while in broadback-arc area, represented with Hengyang, Danxia-Nanxiong and Heyuan Basin, thegeological features are stretch tension in common in the early late Cretaceous, andbelonging to the back-arc rift environment of epicontinental arc system. The dominantfactors of the features maybe related to the recessive subduction zone of Proto-SCS.（3）Volcanic eruptions of Sanshui Basin in Cenozoic opened a preluede of themodern SCS Wilson cycle. Sanshui Basin, Heyuan Basin, Maoming Basin, LedongBasin, Pearl River Mouth Basin,which all keep the Cenozoic geologic record have thebasic characteristic of stable passive continental margin sedimentary, which show thebackground of active continental margin in proto-SCS has succumbed to backgroundof passive continental margin in the modern SCS. In the light of limitation of thecurrent study conditions, the age, which stand for these major tectonic boundariesconversion is difficult to define.