The large deep-water turbidity fan system in southeastern South China Sea Basin: Formation and tectonic constraint

A large turbidite fan system was found from southeastern South China Sea basin through the latest multi-channel seismic profiles in the regional geological and geophysical measurement data set. This fan system occurred in the water depth from 2000 m to 3800 m of the present sea level, with forward northwest direction to the central basin edge 150-260 km in length. The fan system was interpreted to have been formed from middle Miocene to Quaternary with series of turbidite fan sequences, mainly composed of sediment waves, channel filling, submarine fans, and mass flows. In time scale, from the early to late stage, the size and architecture of fan system were constantly changing, underlying valuable information of sea level change, depositional process and tectonic evolution. In spatial scale, the turbidite sand bodies were formed by the superimposed layers of turbidite flow sediments. The channels were well developed on the seabed within this fan system. The bottom of the channel sand bodies are distributed on "V" shape in panel, extending from south to north, revealing mainly sources from Liyue Bank and north Palawan Island area. The turbidite fan's formation was obviously controlled by tectonic movement, on the one hand related to the uplift of Liyue Bank-Palawan Island since the middle Miocene and, and on the other hand related to magmatic activity since the late Miocene. The turbidite current mechanism occurred in the transition of continental margin to abyssal plain in the southeast of the South China Sea, driving particles transportation from shallow sea to deep basin. This new interpreted large turbidite fan system presents an important linkage of "source-to-sink" sedimentary system, and benefits to revealing deep-sea sedimentary evolution process in the South China Sea.