A unique Yellow River-derived distal subaqueous delta in the Yellow Sea

摘要

Newly acquired high-resolution Chirp sonar profiles reveal a unique Yellow River-derived, alongshore distributed, bidirectional (landward and seaward) across-shelf transported, omega-shaped ("OMEGA") distal subaqueous deltaic lobe deposited around the eastern tip of the Shandong Peninsula in the Yellow Sea. This clinoform deposit directly overlies the postglacial transgressive surface, featured by convex-up seafloor morphology, up to 40 m thick locally. Radiocarbon-14 dates from the underlain pre-Holocene and transgressive sediments indicate this distal lobe has formed since the middle-Holocene highstand under a relatively stable sea level. This along-shelf distributed distal clinoform has been deposited mainly by the resuspended Yellow River sediments carried down by the coastal current, interacting with the local waves, tides and upwelling. Collectively, over the past 7000 years, nearly 30 percent of the Yellow River-derived sediment has been re-suspended and transported out of the Bohai Sea into the Yellow Sea. Overall, the Yellow River-derived sediment could reach the -80 m water depth in the central South Yellow Sea, about 700 km from the river mouth; in contrast, a very small fraction of the modern riverine sediment could escape the outer shelf or reach the Okinawa Trough.