Late Quaternary tephrostratigraphy of Baegdusan and Ulleung volcanoes using marine sediments in the Japan Sea/East Sea |
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| Authors: | Chungwan Lim Kazuhiro Toyoda Ken Ikehara David W Peate |
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| Institution: | 1. School of Earth and Environmental Sciences, Seoul National University, Seoul 151-747, Republic of Korea;2. Graduate School of Environmental Science (GSES), Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan;3. Faculty of Environmental Earth Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan;4. Institute of Geology and Geoinformation, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8567, Japan;5. Department of Geoscience, University of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242, USA |
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| Abstract: | Only Ulleung and Baegdusan volcanoes have produced alkaline tephras in the Japan Sea/East Sea during the Quaternary. Little is known about their detailed tephrostratigraphy, except for the U–Oki and B–Tm tephras. Trace element analysis of bulk sediments can be used to identify alkaline cryptotephra because of the large compositional contrast. Five sediment cores spanning the interval between the rhyolitic AT (29.4 ka) and Aso-4 (87 ka) tephras were analyzed using an INAA scanning method. Source volcanoes for the five detected alkaline cryptotephra were identified from major element analyses of hand-picked glass shards: Ulleung (U–Ym, and the newly identified U–Sado), and Baegdusan (B–J, and the newly identified B–Sado and B-Ym). The eruption ages of the U–Ym, U–Sado, B–J, B–Sado, and B–Ym tephras are estimated to be 38 ka, 61 ka, 26 ka, 51 ka, 68–69 ka, and 86 ka, respectively, based on correlations with regional-scale TL (thinly laminated) layer stratigraphy (produced by basin-wide changes in bottom-water oxygen levels in response to millennium-scale paleoclimate variations). This study has allowed construction of an alkaline tephrostratigraphical framework for the late Quaternary linked to global environmental changes in the Japan Sea/East Sea, and improves our knowledge of the eruptive histories of Ulleung and Baegdusan volcanoes. |
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| Keywords: | Late Quaternary Tephrostratigraphy Tephrochronology Japan Sea/East Sea Baegdusan volcano Ulleung volcano |
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