日本地球惑星科学連合2015年大会

講演情報

口頭発表

セッション記号 S (固体地球科学) » S-GL 地質学

[S-GL37] プレート収束境界における堆積盆形成テクトニクスの新たな展望

2015年5月24日(日) 14:15 〜 16:00 103 (1F)

コンビーナ:*伊藤 康人(大阪府立大学大学院理学系研究科物理科学専攻)、高野 修(石油資源開発株式会社技術研究所)、座長:伊藤 康人(大阪府立大学大学院理学系研究科物理科学専攻)、高野 修(石油資源開発株式会社技術研究所)

15:51 〜 15:54

[SGL37-P03] 福島県沖阿武隈リッジ南部の断層形態とその特性

ポスター講演3分口頭発表枠

*千代延 俊1荒戸 裕之1 (1.秋田大学国際資源学部)

The Abukuma ridge extends for more than 100 km from off the Soma to off the Kashima city along Japan Trench where the Pacific Plate is being subducted beneath the North American Plate. 3D seismic survey and its observations were carried out in this area off the Iwaki city, Fukushima prefecture, northeastern Japan by METI (JOGMEC, 2011). We referred to boreholes MITI Jhoban Oki (JAPT. 1993) in order to connect our seismic interpretation and stratigraphic data. As a result, nine seismic horizon (reflectors) were assigned upper limit of Santonian, upper limit of Campanian, upper limit of Maastrichitian, upper limit of Paleocene, upper limit of Oligocene, upper limit of Lower Miocene, upper limit of Middle Miocene, upper limit of Upper Miocene, and upper limit of Pliocene respectively. Abukuma ridge are distributed in north-northeast (NNE) to south-southwest (SSW) trending anticline recognized within pre-Middle Miocene strata. A number of lineaments, normal faults, bunch perpendicular within Abukuma ridge, most of which were initiated in the Cretaceous and had been active through the Paleogene, Miocene, and Pliocene. Fault morphology is classified into west-dipping north-south trending faults and north dipping east-west trending faults. They displaced by several hundreds to tens of meters. The most remarkable feature is the Abukuma ridge structure divided by large faults across the seismic section. It is apparent that there are dividing four areas where large faults and these faults are concentrated. Some of the large faults have significant strike-slip component. Subsurface structures delineated by reflection 3D seismic data suggest a different phase of activities of Abukuma ridge. Fault geometry is reflecting a complicated slip history in this area.