Abstract:

Through samples drilling survey of the ancient lagoon in the western Changxing Island of Liaodong Peninsula, over 100 boreholes samples from 4 different locations from sea to land are being tested for clay turbid water electric conductivity to distinguish the sediments of the land and sea facies of the ancient lagoon plain and to identify the upper bound of the ancient marine layer. The result shows that the upper bounds at different drilling holes are consistent and are about 4.0-4.2 m above sea level, and this level could represents the average high tide line of the highest sea level of the Holocene lagoon plain. By ¹⁴C measurement of the basal peat covering the marine layer, it is suggested that the highest sea-level of Holocene was seen at about 5 800 cal.aB.P. The average sea level of at highest sea-level periods of the Holocene is about 3.4-3.6 m. When this height is compared with the average sea-level (about 2 m) of the high sea level in the eastern part of Dagushan of Liaodong Peninsula, it seems there was a rising at the Bachagou area of the western Liaodong Peninsula. In addition, there are two peaks in the conductivity measurement profile in 9 m deep B3 hole, reflecting two transgressions during Holocene. The largest range of later transgression is up to about 1.2 km away from the modern coastline.

Key words: enlectric conductivity, ancient lagoon plain, peat layer, Holocene, Liaodong Peninsula