Sequence stratigraphy and depositional evolution of the north-eastern shelf (33.9–10.5 Ma) of the Pearl River Mouth basin, South China Sea

The north-eastern shelf successions of the Oligocene to Middle Miocene South China Sea (SCS) have attracted considerable interest because of recent hydrocarbon exploration success. However, their stratigraphic-depositional patterns and interactive controls still remain less understood. Based on integrated analyses of seismic, well-logging, core data and paleontological data, we systematically document the sequence architecture and depositional evolution of north-eastern shelf of the Pearl River Mouth Basin (PRMB) in the northern SCS. The infill of the Late Oligocene to Middle Miocene successions on the north-eastern continental shelf of the PRMB can be divided into three composite sequences (CS3-CS5) and nine sequences. Depositional-geomorphological systems represented on the shelf mainly include inner-middle shelf deltas, shoreface deposits, reefal platforms, shelf sand-ridges and fine-grained deposits. Large-scale shelf-deltaic deposits are prominent in CS3, whereas the rapid Early Miocene transgression, apparently enhanced by tectonic subsidence, caused a great retreat of Hanjiang River-related systems in CS4. The deposition of during 33.9 Ma to 17.5 Ma is constructed by a ‘sandstones-carbonate-shale’ regressive-transgressive cycle in the proximal domain on the northern continental margin of the SCS. A muddy-prone deposition of CS5 is related to the enhanced tectonic subsidence with possible less sediment supply. The NE-striking geomorphic pattern of sand-ridge related systems possibly caused by the intensification of the south-westerly flowing paleocurrent likely related to the Dongsha Movement after ca. 13.8 Ma. The shoreface deposits (23.8–21 Ma) and reefal platform deposits (21–18.5 Ma) served as potential hydrocarbon reservoir and further exploration in shelf area of the SCS.