JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 S (固体地球科学) » S-CG 固体地球科学複合領域・一般

[S-CG65] [EE] 混濁流:発生源から堆積物・地形形成まで

2017年5月25日(木) 13:45 〜 15:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:横川 美和(大阪工業大学情報科学部)、泉 典洋(北海道大学大学院工学研究院)、Svetlana Kostic(Computational Science Research Center, San Diego State University)、阪口 口(国立研究開発法人海洋研究開発機構)

[SCG65-P01] Rock magnetic analyses for understanding of depositional processes of turbidites induced by large earthquakes in Japan Trench

*金松 敏也1池原 研2新井 和乃3宇佐見 和子2 (1.海洋研究開発機構地震津波海域観測研究開発センター、2.産業技術総合研究所 地質情報研究部門、3.高知大学 海洋コア総合研究センター)

キーワード:Turbidite, Japan Trench, Rockmagnetic property

Ikehara et al., 2016 revealed that the thick turbidite depositions corresponding to 2011 and the other two historical large earthquakes were archived in Japan Trench (JPT) basins. It is then crucially important to determine the distributions of those event deposits in space and time for the JPT paleoseismology. In order to understand the details of their depositions as robust evidences for the large earthquake occurrences, rock magnetic analysis was applied to measure variation of the turbidite intervals. Magnetic granulometry provides the information of sediment depositional processes. Particularly monotone fining upward of magnetic grain size in a few meter scales is found as the most unique feature in the studied sediments. Magnetic grain analysis in detail indicates grain fining occur in various modes. Those variations seem to be linked to respective seismo-events. Additionally anisotropy of magnetic susceptibility (AMS) were measured to detect settling process of particle grains form turbidity flows in the intervals of thick turbidites. Generally dominant lineation of AMS is recognized as not single direction in each event interval while grain size decrease upward monotonously. Some lineations reoriented by paleomagnetic declinations are oblique to the strike of JPT trench. This observation may suggest the complex flow in the confined and elongated basins in JPT. It is considered that the variations of magnetic grain size and fabric data are useful to understand the depositional processes of thick turbidites.