Japan Geoscience Union Meeting 2019

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[J] Poster

O (Public ) » Public

[O-03] Poster presentations by senior high school students

Sun. May 26, 2019 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Tatsuhiko Hara(International Institute of Seismology and Earthquake Engineering, Building Research Institute), Katsuyoshi Michibayashi(Department of Earth and Planetary Sciences, Nagoya University), Miwa Kuri(International Research Institute of Disaster Science, Tohoku University), Kou Yamada(Waseda University)

1:45 PM - 3:15 PM

[O03-P06] Magnetic measurement of basalt dikes in the Sara river of Tsuyama

*Hayate Madokoro1, *Yuta Emi1, *Syota Matano1, *Naoyuki Washida1 (1.Okayama prefectural Tsuyama High School)

According to previous studies, there was a warm archipelago, like that of the subtropical zone, in Tsuyama city about 16~7million years ago. In this study, we call the archipelago "the Tsuyama Sea". However, no one has precisely examined factors and dates of the disappearance of the Tsuyama Sea. We measured paleomagnetism of the basalt dikes which are stretching north and south in the Tsuyama Sara River with our own astatic magnetometer. By this measurement, the paleomagnetism showed that magnetic north was shifted 2.4° north-west from the current magnetic north when the dikes had been formed. Therefore, we think that an increase of the north and south compression caused the rising of the backbone range, and after that, the disappearance of the Tsuyama Sea.