南海东北部深部构造与中新生代沉积盆地

RELATIONSHIP BETWEEN THE DEEP STRUCTURE AND CENOZOIC/MESOZOIC SEDIMENT BASINS IN THE NORTHEASTERN SOUTH CHINA SEA

利用OBS资料作约束条件对南海东北部的地球物理资料,主要是重力资料和多道反射地震资料进行反演,获取比较理想的莫霍面深度、地壳厚度、中生代沉积基底面、新生代沉积底界面等地壳结构信息。研究发现该区中生代沉积盆地形成模式与新生代沉积盆地的形成模式不同。中生代沉积基底与莫霍面呈正相关,而新生代沉积基底则与莫霍面呈明显的镜像关系。中生代地层不受边界断层控制,中生代沉积坳陷边界实质上是残留的中生代地层的边界。中生代沉积盆地具有大型坳陷沉积特征,而新生代盆地为断陷盆地。

The authors use the new OBS data published by Taiwan scientists as the constrain conditions to inverse the relation between the gravity anomaly data,multichannel seismic data,and deep seismic data of the northeastern South China Sea. The obtained Moho depth,crustal structure thickness,and Cenozoic and Mesozoic basement show that the formation mechanism of Mesozoic basins is different from that of the Cenozoic basins.The relation between Mesozoic basement and Moho depth is positive,but the Cenozoic basement is in negative correlation with Moho depth.Distribution of Mesozoic strata is not controlled by the northeast direction boundary faults,and the edges of Mesozoic depressions are actually the boundary of the relict Mesozoic strata.This indicates that Mesozoic strata are of large depression characteristics,but the Cenozoic depressions are faultboundary basins.