北康盆地构造特征及其构造区划

北康盆地是位于南沙中部海城的新生代沉积盆地，新生代沉积盖层在盆地内广泛发育，根据地震反射特征及地震反射界面的区域对比，盆地基层可进一步划分为3个构造层。北康盆地西南边界发育延贾断裂，该断裂西起万安盆地，向东直于加里曼丹。从渐新世始，廷贾断裂先后经历了3次规模较大的构造活动。南沙海槽西北缘断裂位于北康盆地的东南边界，该断裂把北康盆地和南沙海槽盆地分隔开来。北康盆地内断裂主要有北东、北西和南北向三组，其中南北、北西向断层往往错断北东向断层。在详细讨论断层特征和沉积盖层布规律的基础上，对北康盆地的二级构造单元进行了划分。

TECTONIC CHARACTERISTICS AND DIVISION OF THE BEIKANG BASIN

Located in mid Nansha waters, the Beikang basin is a Cenozoic sedimentary basin where Cenozoic sedimentary cover rock is extensively developed. The cover rock consists of three structural layers according to seismic reflection. There lies Tingjia fault along southwest boundary of Beikang basin, which originated from Wan'an basin in the west and reached Kalimantan in the east. From Oligocene through Miocene to late Miocene and Quaternary, the fault experienced three tectonic movements on large scales. Northwest fault of the Nansha Trough lies on the southeast boundary of the Beikang basin and has separated Beikang basin from Nansha Trough. There are three series of faults (NE, NW and N S faults) in Beikang basin, and the first fault is always cut by the last two. On the basis of the analysis of the faults and characteristics of the cover layer, the secondary tectonic units were further discussed in this paper.