日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 S (固体地球科学) » S-GL 地質学

[S-GL28] 地域地質と構造発達史

2019年5月27日(月) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:大坪 誠(産業技術総合研究所 活断層・火山研究部門)、細井 淳(産業技術総合研究所地質調査総合センター地質情報研究部門)

[SGL28-P07] Erosional features of Soma Slope Channel, off Miyagi, Japan

*Jih-Hsin Chang1Takahiko Inoue1Ayanori Misawa1Kohsaku Arai1 (1.Geological Survey of Japan, National Institute of Advanced Industrial and Science Technology.)

キーワード:submarine channel, Tohoku, Japan

Located at the boundary between Pacific Plate and North America Plate, Tohoku (NE Japan) is the forearc slope of the active subduction zone, featuring as a tectonically active margin. In the central part off Tohoku, the bathymetric data off Miyagi show that there is a channel (Soma Slope Channel) connecting shallow marine (< 500 m) and slope terrace (>1000 m). The reflection seismic data across the Soma Slope Channel show more than 10 U-shaped and V-shaped reflectors, suggesting that channelized features and filling of the channels. Besides, the channel-shaped reflectors became shallower toward north, suggesting a series of northward migration of the Soma Slope Channel. The reflection seismic data along the axis of the Soma Slope Channel show a several regional erosional surfaces and could be regarded as stratigraphic sequences boundaries. The ages of these stratigraphic sequences boundaries derived from exploration well (MITI Soma-oki) indicates that this slope channel system is likely to develop during Pliocene-Pleistocene. It seems that the Pliocene-Pleistocene sequence are thick and the Miocene-age strata are generally deep south of the Soma Slope Channel, while Pliocene-Pleistocene sequence are thinner and the Miocene-age strata are shallower north of the Soma Slope Channel. Whether the Soma Slope Channel is structural-dominated or sedimentary-dominated as well as the mechanism of channel migration will be discussed in this study.