COMPARISON AND APPLICATION OF SHEPARD'S AND FOLK'SCLASSIFICATIONS TO THE SUBSURFACE MAPPING IN THE SOUTH YELLOW SEA

Both the Shepard's and Folk's classifications of detrital sediments are used in mapping the surficial sediments of the South Yellow Sea.In accordance with Shepard's nomenclature the detrital sediments in the mapping area are divided into sandy silt,silty sand,silt,clayey silt,sand-silt-clay and sand,and following the Folk's classification,they are sand,silt,mud,silty sand,sandy silt,sandy mud,muddy sand,gravelly mud and so on.Results show that the Shepard's classification is only a descriptive one.The three end members of the triangle are equal in significance with no meaning of hydrodynamics.However,the classification proposed by Folk et al treated the three end members of the triangle in accordance with their dynamic significance.The map compiled upon Folk's classification demonstrates that grain size components are the effective indicator of hydrodynamics.The distribution of the sediments,therefore,can indicate the change of the sedimentary environment.The fine components of sediments clearly increase as the environments change from high energy environments to low energy ones.The distribution of sediments also has the function to indicate the provenance of the sediments.In the map,the west part of the South Yellow Sea is dominated by sediment from sand to silt,but the east part by sediments from sand to mud.In this regard,Folk's classification is highly recommended in mapping the surficial sediments in the future offshore mapping programs.