CORRELATION OF OYSTER SHELL FORM AND SEDIMENT ENVIRONMENT FROM TWO BURIED OYSTER REEFS ON THE NORTHWEST COAST OF BOHAI BAY
渤海湾西北岸埋藏牡蛎礁体中的 壳体形态与沉积环境*

Buried oyster reefs are widely distributed over the coastal area in the northwest of Bohai Bay. Form of oyster shells and sediment characters (grain size and percentage of clay) are different in these buried oyster reefs. In this paper, we sampled 58 and 117 specimens of adult oyster shells from Dawuzhuang and Lingtou buried oyster reefs. Samples were washed with fresh water and then dried at room temperature. Weight, height, and volume of both oyster valves were measured. We also sampled nearly 80 muddy samples from these two reef bodies for their grain size analysis. The relationships between shells' weight and height, weight and volume, respectively, are calculated.Results show that forms of the shell from different oyster reefs are different. We found out that the rate of shell weight vs. height in Dawuzhuang is higher than that in Lingtou. However, the rates of shell weight vs. volume are almost the same in two reefs. Furthermore, specimens sampled from Lingtou are characterized by slim valves, but those in Dawuzhuang are relatively round and strong. Corresponding to different types of shell forms, the characters of deposited sediment in the reef bodies are different. While the sediment is fine and has more clay, the valves is slim; while the sediment is coarse and has less clay, the valves is round and strong.As the characters of the growing environment can be recorded on oyster shell, they can be used for the reconstruction of the paleo-environment.