Quantitative reconstruction of Holocene sediment source variations in the Yellow and northern East China Seas and their forcings

Abstract

Sediment provenance in the Yellow Sea and northern East China Seas (YECSs) has long been a subject of interest, but its quantification is still inconclusive. Here, we present an improved Al-Mg regression analysis by refining its methodological approach to strengthen quantification of sediment source-to-sink transports in the YECSs, with focus on its forcing mechanisms during the Holocene. Our quantitative source estimates clearly depict a considerable supply of the Chinese river (CR) sediments (similar to 50%) to the southwestern Korean coastal region, and the Korean river (KR) sediments (30-40%) to the Central Yellow Sea Mud deposit, which accounts for a good balance between the sediment supply and budget of the shelf deposit. Of particular note is an abrupt decline in the CR contributions around 124 degrees E, which indicates that the CR sediments do not directly reach the eastern part of the Yellow Sea blocked by a strong physical boundary. Further, the observed variations in proportions between Huanghe-, Changjiang- and Korean river-derived sediments over the last 15 kyr - notably an abrupt increase of CR contribution since similar to 7 ka, followed by a sudden drop at similar to 3-4 ka - exhibit a good correspondence with other mineralogical proxy records. These temporal provenance changes witnessed robust palaeoenvironmental signals which fit to major climatic and oceanographic events linked with sea-level, intensity of the Kuroshio Current inflow and the East Asian monsoon. This study improves understanding of what pathways and sinks exist within the YECS basin, and how rates of sediment supply from adjacent rivers have changed over time.