VARIATION IN GRAIN-SIZE DISTRIBUTION PATTERN OF THE SOUTHEASTERN LIAODONG BAY AND ITS IMPACT FACTORS

Based on the lithology and grain-size parameters of the two piston cores(LDC30 and LDC25),we studied the changes in sedimentary environment and provenance of the southeastern Liaodong Bay since early Holocene.The lithology and grain-size parameters of the two cores display two step variations,and the sand content and mean grain-size of the upper layers are obviously larger than that in the lower parts.It suggests that the lower section of the sediments is mainly deposited under a nearshore shallow marine environment during the early Holocene transgression,whereas the upper section deposited in the tidal environment since the highest sea level stand (~7 kaBP).The sediment provenance of these two sections in the piston cores is also different with each other,under the control of sedimentary environment changes caused by sea level fluctuation and the terrigenous input variation related to the East Asian summer monsoon.