Japan Geoscience Union Meeting 2014

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Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS30_28AM1] Paleoclimatology and paleoceanography

Mon. Apr 28, 2014 9:00 AM - 10:45 AM 501 (5F)

Convener:*Kazuyoshi Yamada(School of Human Sciences, Waseda University), Minoru Ikehara(Center for Advanced Marine Core Research, Kochi University), Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Ikuko Kitaba(Kobe University Research Center For Inland Seas), Akihisa Kitamura(Institute of Geosciences, Faculty of Science, Shizuoka University), Masaki Sano(Research Institute for Humanity and Nature), Ryuji Tada(Department of Earth and Planetary Science, Graduate School of Science, The Univeristy of Tokyo), Masakazu Yoshimori(Atmosphere and Ocean Research Institute, University of Tokyo), Chair:Kazuyoshi Yamada(School of Human Sciences, Waseda University)

9:00 AM - 9:15 AM

[MIS30-01] diatom assemblages in INW2012 drilling cores from Lake Inawashiro , Tohoku, Japan

*Kotaro HIROSE1, Yoshitaka NAGAHASHI1 (1.1Fukushima University)

Keywords:Lake Inawashiro-ko, lacustrine sediment core, stratigraphy, diatom assemblage, late Pleistocene, 14C dating

Inawashiro-ko Formation is named by a 28.13m sediment core taken from Lake Inawasiro- ko, Fukushima Prefecture, Japan. Stratigraphy and facies analysis combined with tephra and AMS radiocarbon dating were carried out on INW-2012. The Inawashiro-ko Formation are divided into three stratigraphic units: the Lower part (37.17-26.60m) consisted by medium sand-sandy silt (vertically varied in grain size) with granule and wood fragments, the Middle part (26.60-24.89m) consisted by very fine sand-silt with upper level grain refinement, and the Upper part (24.89-0.00m) consisted by dense alternation of brighter and darker clay layers including fallout tephra and Lahars by sediment gravity flow. Each unit are formed by fluvial basin before the form of the lake, early stage of the lake, lake with deep water as present, respectively. 14C dating indicate that Lake Inawashiro-ko is formed 42 cal k BP, and characteristic dense alternation of brighter and darker clay layers deposit continuously except for the most early stage of the Lake. The sedimentation late in the upper part is 0.3-1.0(mm/yr). Additionally, We report the temporal variation of diatom assemblage and its relation to water environment in the past 2000 years from upper 2.00m of IN2012.