Post-glacial sedimentation in a river-dominated epicontinental shelf: The Yellow Sea example.

摘要

The North Yellow Sea (NYS) and South Yellow Sea (SYS), stretching from the Bohai Sea in the north to the East China Sea (ECS) in the south, represents an end member of modern epicontinental seas. Because of its shallow depths, the Yellow Sea was entirely exposed subaerially during the last glacial maximum.; The new post-glacial sea-level curve derived from an extensive local dataset shows a series of rapid flooding events (12–45 mm/y), separated by a series of slow rises (2–6 mm/y). By about 15 ka, sea level had reached −100 m, and seawater entered the SYS. A rapid rise during MWP-1A occurred between 14.7–14.1 ka, sea level jumped from −98 m to −74 m (40 mm/yr). At the end, the sea water had reached the southern edge of the NYS, after which sea level rose again slowly (6 mm/yr) from −72 m to −60 m. Beginning about 11.7 ka, it again jumped, from −60 m to −42 m (MWP-1B), resulting in a rapid westward flooding of the NYS. Sea level then again stagnated (between −42m to −36 m) for about 1.8 ky. Starting about 9.8 ka, the sea-level advanced again from −36m to −16 m at 9.0 ka (MWP-1C), after which most of BS, YS, and ECS had been submerged. Then another slowdown occurred between 9.0–8.0 ka when sea-level rose from −16m to −10m. The last major transgression happened between 8.1 and 7.0 ka (MWP-D), and resulted in Holocene highstand of at least +2 to 4 m along most of Chinese and Korean coastlines.; Sequence structures on this epicontinental shelf show strong landward horizontal changes, instead of the vertical changes. The first major deltaic system was developed in the NYS together with the decreased sea-level rise after MWP-1B event, and the intensified summer monsoon and subsequent increased river discharge at about 11 ka. The second subaqueous delta was built in the SYS between 9–7 ka which during another slackened sea-level after MWP-C. The modern subaqueous and subaerial deltas in the west Bahai Gulf have been formed during the sea-level highstand after the last jump of MWP-1D.