Spatial distribution of sedimentation rates in the eastern Japan Sea off Akita

Abstract

Spatial distribution of sedimentation rates was estimated in the large area from the shelf to the Yamato Basin in the eastern Japan Sea off Akita, using depths of reflectors on 3.5 kHz sub-bottom profiler (SBP) records and estimated ages of the reflectors. Sedimentation rates remarkably change between the Tobishima-Oga Basins and the Mogami Trough, and between the Mogami Trough and the Sado Ridge areas. They are estimated more than 60 cm/ky on the shelf and the Tobishima-Oga Basins, 15-50 cm/ky on the Mogami Trough, 5-10 cm/ky on the Sado Ridge and the Yamato Basin on the average. These differences are thought to reflect the contribution of sediment transport through the bottom layer controlled by the topographic barriers as well as the distance from the sediment sources. Sedimentation rates also vary in each region according to the small-scale topography, folds or faults. It is expected that the spatial distribution of sedimentation rates is estimated more widely because muddy sediments are distributed and acoustic reflectors can be traced widely in the Japan Sea.