New archive of another significant potential sediment source in the South China Sea

Sediment provenance is an important part of the sediment source-to-sink transport process from land to sea. However, we sometimes cannot explain some contradictory problems well when assessing sediment sources in certain areas. The northern South China Sea (SCS) is currently considered to be dominantly supplied with sediments from the Pearl River, Taiwan and Luzon. For smectite (one type of clay mineral), Luzon is normally thought to be a significant source when considering only the high smectite percentages in Luzon-derived sediments and neglecting their limited sediment discharge into the sea and longer transport distance of its sediments from this island. Recently, clay mineral compositions of the Pearl River originated sediments were reported to change from rich in smectite from similar to 2500 years ago due to the anthropogonic activities. By contrast, the wide area in the east of the Pearl River (EPR) is similarly characterized by sediments with high smectite percentages and a shorter transport distance than those from Luzon. However, a previous study showed that surface sediment samples with high smectite percentages were occasionally distributed in bays. Here, we present a sediment archive of 16 gravity cores from neighboring bays/harbors along the northern SCS coast. Unlike surface sediments with low smectite percentages, core sediments from the coastal bays/harbors of the EPR show high smectite percentages, indicating that the EPR besides the Pearl River and/or Luzon might be as another potential sediment source for the northern SCS. In South China, widely distributed igneous rocks/volcanic materials are prodigious sources for sediments in the northern SCS slope. In future work, weathering of local materials must be considered when differentiating various sediment sources.