Primary report on seafloor sediment sampling in the northeastern East China Sea and western Sea of Japan

As part of the Marine Geological Map Project of the Geological Survey of Japan, the geological survey cruise GB23 was undertaken in the northeastern East China Sea and western Sea of Japan.Although the water depth over most of the survey area is <200 m, deeper areas also exist, such as the Goto Canyon (water depth: 400-600 m) and the area southwest of the Goto islands and the Danjo Basin (maximum water depth: ~800 m).Seafloor sediment was sampled at 198 sites using a Kinoshita grab sediment sampler, a vibro-corer, a rock dredger, and a rock corer.Here we report the characteristics of seafloor sediments collected using the Kinoshita grab sediment sampler.Coarse sediment with a low mud content occurs in the Tsushima Straight.Finer sediment with a high mud content occurs in other parts of the survey area.The seafloor sediments contain bioclasts such as mollusc shells and coral remains, including fossilized shells.This report also presents preliminary results on the calcareous nannoplankton and main planktic foraminifera in the seafloor sediment samples.