[H-CG23] Earth surface processes related to deposition, erosion and sediment transport

[HCG23-P05] Sedimentary characteristics of the upper Pleistocene mixed sand and gravel coastal succession, the eastern Kanto, central Japan

*Hiroko Okazaki¹, Toru Tamura^2,3 (1.Fukada Geological Institute, 2.Geological Survey of Japan, AIST, 3.Graduate School of Frontier Sciences the University of Tokyo)

Keywords:sand and gravel coast, sedimentary facies, upper Pleistocene, eastern Kanto

Sand and gravel layers with well-developed cross-bedding are recognized in the upper part of the upper Pleistocene along the Pacific coast in the eastern part of the Kanto Plain. The layers are coastal deposits, in which trace fossil Macharonichnus segregatis are included. The sedimentary facies change horizontally: the gravel layers with planar bedding, sand and gravel layers with large trough and tabular beddings, which becomes sandy downstream, with a thin layer of coarse-grained gravel at the base. Additionally, there are lenticular or shallow scours filled with sands which form chutes-and-pools. These layers are prograding to offshore obliquely. The formation of the sand and gravel layers is attributed to coastal topography and waves during storms.