摘要
In order to further understand the central canyon system(CCS) in Qiongdongnan Basin(QDNB),a large axial submarine canyon,the present study described and dissected morphological characteristics and internal architectures of the CCS based on 2D and 3D seismic data,and the result indicated that the CCS in QDNB can be characterized by "segmentation" and "multi-phases".Based on integrated comparisons and analyses of different segments and evolution phases of the CCS and combined with changes of tectonic-sedimentary conditions of QDNB,we could divide the sedimentary evolution of the CCS into 4 phases,i.e.an initial development phase in Late Miocene(11.6 Ma-5.7 Ma),an eroded-infilling phase in Early Pliocene(5.7 Ma-3.7 Ma),a tranquil infilling phase in Late Pliocene(3.7 Ma-1.81 Ma) and a rejuvenation phase since Pleistocene(since 1.81 Ma).The regional tectonic transformation at late Middle Miocene(11.6 Ma) initiated the formation of an axial sub-basin in the eastern QDNB,which can be regarded as a rudiment of the CCS.In Early Pliocene,abundant sediments supplied the basin from the northwestern and northern sources,and the limitation from the southern uplift belt and the geomorphology of the eastern QDNB would constrain the developing course of the CCS from west to east and confine the canyon within the central depression belt.Because of the lack of deposits during Late Pliocene,the CCS then only developed in the eastern QDNB.Climate factors,a distributary effect of the northern seamount and the topography of the eastern QDNB have co-controlled the development of the modern central canyon system since Pleistocene,which is called as a rejuvenation phase of the CCS.