Sedimentary evolution of the Central Canyon System in the Qiongdongnan Basin, northern South China Sea

Abstract

Abstract: This study elucidates sedimentary evolution history of the Central Canyon System (CCS), a large axial submarine canyon in the Qiongdongnan Basin (QDNB), northern South China Sea. The geomorphological characteristics and infill architectures of the CCS are summarized based on the analysis of two- and three-dimensional seismic data. Based on a comparative analysis of the CCS in different segments and evolutionary stages and in consideration of the tectono-sedimentary conditions of the QDNB four stages of the sedimentary evolution of the CCS can be divided, i.e., initial development stage in the Late Miocene (11.6–5.7 Ma), erosion - infilling stage in the Early Pliocene (5.7–3.7 Ma), tranquil infilling stage in the Late Pliocene (3.7–1.81 Ma), and rejuvenation stage since the Pleistocene (1.81 Ma to present). In the late Middle Miocene (~11.6 Ma), the rudiment of CCS was developed by a regional tectonic transformation in the eastern part of the basin. In the Early Pliocene, the CCS was further developed from west to east and restrained in the central depression belt of the basin due to abundant sediment supplies from the northwestern and northern provenances, the blocking effect of the southern uplift belt, and the restrictive geomorphological features of the eastern part of the basin. In the Late Pliocene, changes in the sedimentary environment resulted in the development of the CCS in the eastern part of the basin only. Since the Pleistocene, the joint action of climatic factors and geomorphological features of the eastern part of the basin led to the rejuvenation of the CCS. Key words: Central Canyon System, sedimentary evolution, Late Miocene, Qiongdongnan Basin, northern South China Sea