Stratigraphic correlation of subsurface Neogene deposits in the Kanto Plain, central Japan

Microfossil biochronology was examined for sixteen deep observation wells of the National Research Institute for Earth Science and Disaster Prevention (NIED). The subsurface Neogene marine sediments in the Kanto Plain are divided into three stratigraphic units; "N. 8 deposits", "post N. 8 deposits" and Kazusa-Shimousa Groups, in ascending order. Upper two units widely distribute beneath the Kanto Plain. "Post N. 8 deposits" covers the pre-Neogene basement rocks unconformably at most localities. In contrast, the "N. 8 deposits" is recognized from a few sites, which may represent the sporadic distribution of this unit in the Kanto Plain. Microfossil geochronology of subsurface geology suggests that the "post N. 8 deposits" can be divided into the Middle to Late Miocene intra-arc basin fills and overlapping Pliocene fore-arc basin sediments.