Japan Geoscience Union Meeting 2014

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Symbol M (Multidisciplinary and Interdisciplinary) » M-TT Technology & Techniques

[M-TT42_2AM2] Frontiers in Geochemistry : Innovative approaches for Earth and Planetary Sciences

Fri. May 2, 2014 11:00 AM - 12:45 PM 314 (3F)

Convener:*Yusuke Yokoyama(Atmosphere and Ocean Research Institute, University of Tokyo), Hiroyuki Kagi(Geochemical Laboratory, Graduate School of Science, University of Tokyo), Shogo Tachibana(Department of Natural History Scieces, Hokkaido University), Takafumi Hirata(Graduate School of Science, Kyoto University), Urumu Tsunogai(Graduate School of Environmental Studies, Nagoya University), Katsuhiko Suzuki(Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology), Gen Shimoda(Geological Survey of Japan, AIST), Hirochika Sumino(Geochemical Research Center, Graduate School of Science, University of Tokyo), Hajime Obata(Marine inorganic chemistry division, Atmosphere and Ocean Research Institute, University of Tokyo), Yoshio Takahashi(Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University), Tetsuya Yokoyama(Department of Earth and Planetary Sciences, Graduate School of Science and Engineering, Tokyo Institute of Technology), Chair:Hiroyuki Kagi(Geochemical Laboratory, Graduate School of Science, University of Tokyo), Shogo Tachibana(Department of Natural History Scieces, Hokkaido University), Yusuke Yokoyama(Atmosphere and Ocean Research Institute, University of Tokyo)

11:30 AM - 11:45 AM

[MTT42-10] Coral growth-rate insensitive Sr/Ca as a robust temperature recorder at the extreme latitudinal limits of Porites

*Shoko HIRABAYASHI1, Yusuke YOKOYAMA1, Atsushi SUZUKI2, Yuta KAWAKUBO1, Yosuke MIYAIRI1, Takashi OKAI2, Satoshi NOJIMA3 (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.National Institute of Advanced Industrial Science and Technology, 3.Amakusa Marine Biological Laboratory, Kyushu University)

Corals are rich archives of climatic changes with high-resolution record of seasonal change such as sea-surface temperature(SST), in tropical and sub-tropical seas during recent and distant past. Past SST are commonly reconstructed from the trace elementals present in annually-banded coral skeletons. Recently, reef building corals were found in temperate regions due to coral habitat range shifts and/or expansions. Therefore, it could be a powerful tool for reconstructing climatic changes such as global warming and ocean acidification over long period. However, because of the more stressful environment for corals in temperate region than tropic or subtropics, we have to know how to reconstruct palaeo-SST using temperate corals. This paper was reported Sr/Ca-based SST reconstructions for temperate Porites corals collected from Kyushu, Japan, near the northern latitudinal extent of hermatypic corals. New, high-resolution Sr/Ca data, measured along the growth axes of Porites from Ushibuka, were compered to previously published δ 18O data from the same specimens (Omata et al., 2006). Results indicate that Sr/Ca variations in a low-growth coral remain independent from growth rate, in contrast to the oxygen isotope ratios of the same coral. Results clearly indicate that Sr/Ca robustly reproduces SST variations from regions along the extreme latitudinal limits of hermatypic coral habitat, independent of growth rate variations. Additionally, Sr/Ca of the other two Porites corals collected in Ushibuka were measured and the inter-colony variation of reconstructed SST was shown. At this stage, it is difficult to reconstruct accurate SST using only one specimen of Porites in temperate region. However, we can reconstruct SST within only 1℃ difference from observed SST if we calibrate Sr/Ca-SST using more than two corals. It is expected that in the future the fossil temperate corals will be commonly used for paleo-SST reconstruction.