Japan Geoscience Union Meeting 2015

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

[M-IS34] Paleoclimatology and paleoceanography

Thu. May 28, 2015 4:15 PM - 6:00 PM 301A (3F)

Convener:*Kazuyoshi Yamada(Museum of Natural and Environmental history, Shizuoka), Minoru Ikehara(Center for Advanced Marine Core Research, Kochi University), Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Akira Oka(Atmosphere and Ocean Research Institute, The University of Tokyo), Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Ikuko Kitaba(Research Centre for Palaleoclimatology, Ritsumeikan University), Akihisa Kitamura(Institute of Geosciences, Faculty of Science, Shizuoka University), Masaki Sano(Research Institute for Humanity and Nature), Takeshi Nakagawa(Ritsumeikan University), Akira Hayashida(Department of Environmental Systems Science, Doshisha University), Chair:Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University)

5:00 PM - 5:15 PM

[MIS34-20] High-resolution climate variations during the last interglacial period from an Osaka Bay core

*Sanae SHIBUTANI1, Ikuko KITABA2, Masayuki HYODO3, Shigehiro KATOH4, Hiroshi SATO5 (1.Earth Planet. Sci., Kobe Univ, 2.Res. Ctr. for Palaeoclim., Ritsumeikan Univ., 3.Kobe Univ. Res. Ctr. Inland Seas, 4.Hyogo Museum, 5.Inst. Nat. Environ. Sci., Univ. Hyogo)

Keywords:Last interglacial, Paleoclimate, Osaka Bay, Pollen analysis

The last interglacial period is characterized by an extremely high sea-level and warm climate. To reveal detailed features of climate for this period, pollen analyses were conducted on a sedimentary sequence in a 1700-m core from Osaka Bay. At least 400 tree pollen grains were counted for each sample. A marine sediment layer correlated with the last interglacial ranges in depth from 73.6 m to 61.4 m, with the highest sea-level at 69.5 m according to diatom assemblage data. An average sedimentation rate of 0.548 m/ka (R=0.999) is calculated with nine age control points above marine isotope stage (MIS) 17 in the core. A linear age model using the average sedimentation rate and calibrating the sea-level peak to the MIS 5e highstand (Rohling et al., 2008) suggests the marine layer spans in age from 130 ka to 108 ka. The time span almost agrees with that of MIS 5e. The climate change based the age model is as follows. Before 130 ka, Picea is dominant, indicating a cold climate during MIS 6. From 130 to 125 ka, the proportion of cool-temperate deciduous broadleaved taxon Fagus gradually increases, suggesting gradual warming, coinciding with the postglacial sea-level rise that is shown by the gradual increase of pelagic diatom Thalassiosira spp. After 125 ka, Fagus turns to decrease, while Quercus including warm-temperate evergreen broadleaved taxon Quercus (Cyclobalanopsis) gradually increases and reach a maximum. The thermal maximum occurs slightly after the highest sea-level. After 115 ka, temperate conifers Cryptomeria, Sciadopitys and Taxaceae-Cephalotaxaceae-Cupressaceae begin to increase, suggesting a gradual wetting. The wet climate continues even after MIS 5e. Subtropical taxon Lagerstroemia occurs throughout the last interglacial. These climate variation features seem to be consistent with those of the last interglacial climate from Lake Biwa.