PALAEOECOLOGICAL ENVIRONMENT REVEALED BY THE BURIED BINHAIHU OYSTER REEF ON THE NORTHWEST COAST OF BOHAI BAY

Holocene buried oyster reefs were widely distributed over the coastal areas in the northwest Bohai Bay. All the reefs were exclusively covered with 1 to 6 m thick muddy sediments. In the old days, it was nearly impossible to obtain the distribution of a whole individual oyster reef, and there was no proper opportunity to sample sediments throughout the whole section of a reef body, including the underlying and inside-reef-body filling muddy deposits as well. In this study, with excavator and handle driller, the distribution of the Binhaihu oyster reef is revealed and sequential sampling is also given from the underlying to the upper portion of the reef body.
The results indicate that the reef, 2 m for its mean thickness and located in an estuary while it was living, extended its body along the riverbed in the direction of NW-SE. It started at 2 445 cal BP with the body-basement located on subtidal zone and at around 2 287 cal BP after nearly 160-year-buildup, the top portion of reef body reached the position of mean sea level. Then, it ceased building-up following the shoreline progradation and the reef was covered with muddy deposits.