Japan Geoscience Union Meeting 2014

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Oral

Symbol S (Solid Earth Sciences) » S-VC Volcanology

[S-VC53_28PM2] volcanic activities and tectonics

Mon. Apr 28, 2014 4:15 PM - 4:45 PM 413 (4F)

Convener:*Nobuo Geshi(Geological Survey of Japan, The National Institute of Advanced Industrial Science and Technology), Takuya NISHIMURA(Disaster Prevention Research Institute, Kyoto University), Ryuta FURUKAWA(Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology), Daisuke MIURA(Geosphere Sciences, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry), Takeshi Hasegawa(Department of Earth Sciences, College of Science, Ibaraki University), Kiyoshi Toshida(Geosphere Science Sector, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry), Chair:Yasuhisa Tajima(NIPPON KOEI CO.,LTD.)

4:30 PM - 4:45 PM

[SVC53-P06_PG] The Middle Miocene tectonics and volcanism in the intra-arc and the back-arc region, Northeast Japan

3-min talk in an oral session

*Jun HOSOI1, Kazuo AMANO2 (1.Graduate School of Science and Engineering, Ibaraki University, 2.Faculty of Science, Ibaraki University)

Keywords:Miocene, tectonics, back-arc, intra-arc, greentuff, Northeast Japan

In northeast Japan, many submarine volcanic rocks related to opening of the Japan Sea in the Early Miocene are widely distributed. They are very important to consider the evolutional process of Japan Arc and to elucidate the submarine volcanism. Despite the importance, there were no detailed sedimentological studies of these volcanic rocks, and the detailed sedimentary processes, sedimentary basin formation, paleo-volcanism and tectonics were poorly understood. In this study, we tried to reconstruct the detail volcanic edifices and volcanism based on the facies analysis of volcanics in typical two area; one is Ou Backbone Ranges in Nishiwaga town, Iwate prefecture and the other is Dewa Mountains in Sakata, Yamagata prefecture, that were located in the intra arc and the back arc in the Miocene respectively. As results, we could elucidate paleo volcanism in each area. Remarkable tectonic change occurred in 15Ma with active volcanism, counterclockwise rotation and rapid subsidence (Hosoi et al., 2013). Regional paleostress around 15 to 12Ma is NW-SE tensional stress (Otsuki, 1989; Hosoi, 2013). This tectonic change happened in 15Ma with opening of Japan Sea, and active bimodal volcanism, rotation movement and tectonic subsidence occurred. [References]Hosoi, J., 2013, Research Report for the Fukada Grant-in-Aid in the H24 fiscal year, 9-23.Hosoi, J. et al., 2013, Jour. Sediment. Soc. Japan, 72, 141-146. Sato, H. and Amano, K., 1991, Sedimentary Geology, 74, 323-343.