[H-QR04] Quaternary, Diachronic dynamics of human-environment interactions

[HQR04-P04] Environmental change from diatom analysis since MIS7 to Jomon Transgression in the Omoikawa lowland and North Nakagawa lowland, the Kanto plain

*Marie Noguchi¹, Shigeko Ishiwata, Shigeto Osato², Toshihiko Sugai³, Suginaka Yusuke⁴, Kunihiko Endo⁵ (1.Paleo Labo co.,ltd., 2.Doshitsu Research Corporation, 3.Department of Natural Environmental Studies, Institute of Environmental Studies, Graduate School of Frontier Science, The University of Tokyo, 4.Research Center of Computational Mechanics, Inc., 5.Nihon University)

Keywords:diatom analysis, Jomon Transgression, MIS5e, Kurihashi, Goka, Boring core

Paleoenvironments of MIS7 to MIS1 in the northern part of Nakagawa Lowland and Omoikawa Lowland were investigated . During the Holocene, marine transgression reached to Kurihashi area, but not to Omoikawa Lowland (Noguchi et al., 2017).
At the eastern side of Omoikawa and Nakagawa Lowlands, Koga terrace (MIS5a to MIS5e, Kaizuka et al., 2000) is situated, extending to Kurihashi. Goka terrace is very low terrace near Kurihashi. Tone River is going through Koga terrace and Goka terrace, by construction of the new cahnnel. At a result, topographical and geological conditions in Kurihashi and Goka areas are very complicated.
We analyzed the topography and geology in this area using many boring data. This shows the Goka terrace is composed of Joso F. (MIS5c) and marine mud of MIS5e below -14m. The latter may be the same horizon as C unit of Omoikawa core, which is characterized by inner-bay environment by diatom analysis.
From these, paleoenvironments during Inner-Tokyo Bay (MIS1) and Paleo-Tokyo bay (MIS7 to MIS5) , along with the basal topography of Chuseki-so will be discussed.