Sedimentary evolution of the Zhongjian Reef in the South China Sea

A large number of reefs are developed on the continental shelves, slopes and basement highs of the deepwater basins in the South China Sea (SCS) since Neogene. The ages and depositional characteristics of the reefs vary from region to region and are mainly controlled by the depositional environments and basement movement. Compared with the Xisha Islands, the Zhongjian reef is an isolated reef developed on an uplift on the northern continental slope of the South China Sea. Based on the surveys of the modern reefs made by predecessors, a two-dimensional seismic survey and boat loading magnetic explorations have been carried out this time. Based on the analysis of seismic sequence stratigraphy, in addition to integrated interpretation of gravity, magnetic and seismic data for depositional environments, five seismic sequence boundaries are identified at the Zhongjian reef. The lithological characteristics and forming time of the Zhongjian reef basement are preliminarily defined. Through the studies of the fan deposits in front of the reef, it is found that the Zhongjian reef has undergone three stages of development in Miocene, Late Miocene and Pliocene respectively. Key words: basement characteristics; sedimentary characteristics; Zhongjian reef