Late Pleistocene delta and its controlling factors on the shelf of Yinggehai Basin in the northwestern South China Sea

The continental shelf area of the Yinggehai Basin in the northwestern of the South China Sea is an important tectonic unit bearing rich information on sedimentation and sea level changes since the Quaternary. Based on the interpretation of the high-resolution single-channel seismic profiling in this area, combined with the drilling data in the deep water area, the sedimentary characteristics of the Late Quaternary strata in the area were analyzed. The shallow stratum of the study area could be divided into two stratigraphic units: unit A and unit B. The seismic characteristics of the delta plain, delta front, and front delta in the study area were recognized and analyzed. The age-dating results using accelerator mass spectrometry ¹⁴C and optically stimulated luminescence indicate that the delta formed during 65～56 kaBP of the Late Pleistocene. Combined with regional geology and sedimentary background, the control factors of delta formation were analyzed. It is believed that the structure and paleo-geomorphology of the Yinggehai Basin, the uplift of Hainan Island, the supply of provenance, and sea level change are important factors controlling the formation of delta.