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)

5:30 PM - 5:45 PM

[MIS34-22] Salinity change in the tropical western Pacific at 5.2 ka when an abrupt tropical climate change occurred

*Mayuri INOUE1, Terrence M. Quinn2, Frederick W. Taylor2, Atsushi SUZUKI3, Hodaka KAWAHATA4, Daisuke ARAOKA5, Yuhei MITSUKAWA1, Minoru IKEHARA6, Hai Cheng7, R. Lawrence Edwards7 (1.Graduate School of Natural Science and Technology, Okayama University, 2.Jackson School of Geosciences, The University of Texas, 3.Geological Survey of Japan National Institute of Advanced Industrial Science and Technology (AIST), 4.Atmosphere and Ocean Reseaarch Institute, The University of Tokyo, 5.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 6.Center for Advanced Marine Core Research, Kochi University, 7.Department of Earth Sciences, University of Minnesota)

It has been reported that an abrupt mid-Holocene climate event that marked the transition from early Holocene (pre-5,000-yr-B.P.) conditions to cooler, late Holocene (post-5,000-yr-B.P.) conditions was widespread and spatially coherent through much of the tropics. This abrupt event was occurred around 5,200 yr ago and was coincident with structural changes in several civilizations. While these evidences are obtained from ice core records and/or lake levels, little has been discussed using marine data. Especially, obtaining accurate estimate of the past δ18O (salinity) distribution in tropical surface waters is crucial to establishing the role of the tropical oceans in global climate change. In this study, Sr/Ca ratios and δ18O values in a fossil coral collected from Vanuatu were measured to reconstruct past sea surface temperature (SST) and salinity. The age of the fossil coral is 5212 ± 10 based on the precise U-Th dating method. Sr/Ca and δ18O were then analyzed with an approximate time resolution of 2 month. XRD analysis and SEM observation revealed that skeletal material was composed of only aragonite. As a result, slightly higher mean SST and about 0.5 per mil enrichment of δ18O relative to modern seawater have shown from 5.2 ka coral. The result is corresponding to the previous study from Great Barrier Reef which has suggested that the temperature increase enhanced the evaporative enrichment of δ18O in seawater.