Grain-size change of delta front sediments accompanied with delta progradation: an example from the Kiso River delta

Abstract

This study examined grain-size changes of delta-front sediments in the Kiso River delta associated with progradation. The mud content decreases from the prodelta to the delta front deposits, and it becomes less than 50% in the lower part of the delta front. The horizon occurs commonly at 10-15 m below the present sea level. The median grain size of sand fraction close to the horizon is approximately 0.1-0.2 mm at most sites. The maximum median grain size of sand constituting the delta front deposits appears in the horizon with low mud content.