APPLICATION OF ACOUSTIC SUBBOTTOM PROFILING TECHNOLOGY TO PROSPECT THE SITE OF ARTIFICIAL ISLAND IN JINZHOU BAY

The acoustic subbottom profiling technology is a geophysical method based on acoustical principle to continuously detect underwater stratigraphic structure and tectonics. Because of its high sensitivity, resolution, continuity and the ability of efficiently detecting the characteristics and distributions of underwater geological formations, it has been widely used in marine engineering prospect. An artificial island will be built in the Jinzhou Bay, Bohai Sea, where the sedimentary are gradually formed with the eustatism and transgression or retreat process since late Pleistocene. From top to bottom,the soilstrata are as follows: neritic facies silt or silty clay, littoral facies silt, continental facies clay, littoral facies silty clay, interbedded of marine and continental facies clay and silty clay. The typical acoustic subbottom profiles from Jinzhou Bay, Bohai Sea are analyzed and interpreted. Eight continuous strong acoustic reflection interfaces are recognized, and six acoustic sequences which have depositional environmental significance are confirmed. The thickness distribution of modern sedimentary and the depth distribution of bedrock are analyzed. According to the comparative study with the sedimentary stratigraphic and lithologic units of the engineering geological drillings, there is a good correspondence between the acoustic sequences confirmed by the subbottom profile and the geological strata of the drilling core. Therefore, the depositional environment is also deduced.