Geomorphology of Goto shelf channels off northern Kyusyu, Japan.

Abstract

The remarkable shelf channels, named Goto shelf channels, were confirmed on the bottom on the southern Tusima strait area off western Kyusyu by the detailed survey of the Hydrographic Department of Japan. These channels consist of three major channel groups from the east to west side of the area, those names are Higasi Goto Shelf Channel, Tyuo Goto Shelf Channel, and Nisi Goto Shelf Channel. The three shelf channels are in junction with each other in the west off Hukue-Sima of Goto Retto and reach to the Goto basin through the Goto submarine canyon. The existence area of the sheIf channels was effected by the Philippine Sea plate tectonic movement as a plate boundary of the Asian and Philippine Sea plate. Also, eustatic sea level changes in the glacial age effected the sea bottom configuration due to submarine erosion, transportation and deposition. During the regression of the glacial age, the channel became narrow, or land between the Korean and Kyusyu districts. At that time, the mouth of the shelf channels formed deltas, estuaries and sandbanks near coastal areas. At the present time, some topographic relict remain, and tidal currents have reformed the submarine topography. Regional tectonic movement reformed bottom configurations as an additional effect.