JpGU-AGU Joint Meeting 2017

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[JJ] Oral

H (Human Geosciences) » H-QR Quaternary research

[H-QR05] [JJ] Diachronic dynamics of human-environment interactions

Thu. May 25, 2017 9:00 AM - 10:30 AM 106 (International Conference Hall 1F)

convener:Toshihiko Sugai(Department of Natural Environmental Studies, Institute of Environmental Studies, Graduate School of Frontier Science, The University of Tokyo), Mamoru Koarai(Earth Science course, College of Science, Ibaraki University), Kiyohide Mizuno(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology), Minoru YONEDA(The University Museum, The University of Tokyo), Chairperson:Toshihiko Sugai(Department of Natural Environmental Studies, Institute of Environmental Studies, Graduate School of Frontier Science, The University of Tokyo), Chairperson:Kiyohide Mizuno(Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology)

9:45 AM - 10:00 AM

[HQR05-04] Tephrochronology of the lowest Kazusa Group distributed in the Boso Peninsula, Chiba Prefecture , Japan

*Itoko Tamura1, Kiyohide Mizuno2, Masayuki Utsunomiya2, Terumasa Nakajima2, Haruo Yamazaki1 (1.Department of Geography,Graduate School of Science,Tokyo Metropolitan University, 2.Research Institute of Geology and Geoinformation, Geological Survey of Japan, AIST)

Keywords:Kazusa Group, Age, Namihana Formation, Katsuura Formation, Widespread tephra correlation, Tephrochronology

The Kazusa Group distributed in the Boso Peninsula, Chiba Prefecture, Japan.
In order to characterize the tephra layers with in the lowest Kazusa Group, authors investigated the thickness, color, shape of volcanic glass, mineral composition, refractive index of volcanic glass and the majer and trace element composition of volcanic glass. Two tephra layers in the Namihana and the Katsuura Formation of the lowest Kazusa Group can be correlated with tephra layers of the other Plio-Pleistocene Groups in central Japan. The KW1 and KW2 tephra layers in the lowest Kazusa Group are correlated with the Jwg3-Okr10 tephra(2.388 Ma) and Fup-OK2 tephra(2.2-2.3 Ma). The age of the lowest Kazusa Group is about 2.4 Ma by these tephra correlations.