Japan Geoscience Union Meeting 2016

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

[M-IS17] Paleoclimatology and paleoceanography

Mon. May 23, 2016 1:45 PM - 3:15 PM A04 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Minoru Ikehara(Center for Advanced Marine Core Research, Kochi 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), Ryuji Tada(Department of Earth and Planetary Science, Graduate School of Science, The Univeristy of Tokyo), Takeshi Nakagawa(Ritsumeikan University), Akira Hayashida(Department of Environmental Systems Science, Doshisha University), Chair:Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University)

1:45 PM - 2:00 PM

[MIS17-01] The potential for a high-resolution, Quaternary paleo-observatory network in the Japan, Yamato, and Ulleung Basins

*Ryuji Tada1, Tomohisa Irino2, Ken Ikehara3, Akinori Karasuda1, Song Lu2, Arisa Seki1, Saiko Sugisaki3, Chang Xuan4, Takuya Itaki3, Takuya Sagawa5, Yoshimi Kubota6, Richard W Murray7, Carlos A Alvarez Zarikian8, Exp 346 Scientists (1.Department of Earth and Planetary Science, Graduate School of Science, The Univeristy of Tokyo, 2.Graduate School of Environmental Science, Division of Earth System Science, Hokkaido University, 3.Reserch Institute of Geology and Geoinformation, Geological Survey of Japan, 4.School of Ocean and Earth Science, University of Southampton, 5.School of Natural System, Graduate School of Natural Science and Technology, Kanazawa University, 6.Department of Geology and Paleontology, National Museum of Nature and Science, 7.Earth and Environment, Boston University, 8.International Ocean Discovery Program, Texas A & M University)

Keywords:High-resolution, Quaternary, paleo-observatory network, IODP Expedition 346

The Quaternary hemi-pelagic sediments of the Japan, Yamato, and Ulleung (JYU) basins are characterized by centimeter- to decimeter-scale alternations of dark (org-C rich) and light (org-C poor) clay to silty clay that are known to reflect variations in the East Asian summer monsoon (EASM) in association with millennial-scale abrupt climatic changes known as Dansgaard-Oeschger Cycles (DOC). These dark layers can be traced across the deeper (>500 m water depth) parts of the JYU basins, and therefore can be used as synchronous markers.
In the summer of 2013, IODP Expedition 346 drilled 7 sites in the JYU basins, and the 6 sites deeper than 800 m water depth are characterized by dark and light layering. Intercalation of the dark layers show millennial-scale variations in dark and light layers started c. 1.45 Ma with over 250 dark layers deposited repeatedly since then. In addition, approximately 100 tephra layers have been correlated across these 6 sites, and as a result we have obtained over 300 time slices with an average resolution of 5 k.y. covering the entire JYU basins.
We have constructed an age model for the Quaternary interval at Site U1424 off Akita using 10 geomagnetic polarity boundaries and 12 marker tephra layers as time constraints. This was then tuned using the gamma ray attenuation density (GRA) profile, which reflects diatom abundance, to the LR04 d18O stack to develop an age model of higher resolution and precision. This high-resolution and high-precision age model is projected to the other 5 sites using the correlation of dark layers and tephra layers. In this way, we have constructed a high-resolution paleo-observatory network from which to assess leads and lags in northern hemisphere climate. We will present a few examples of how to utilize the network.