5:33 PM - 5:36 PM
[SCG57-P26] Reassessment of the stress history in the eastern Boso Peninsula, central Japan
3-min talk in an oral session
Keywords:Boso Peninsula, stress history, fault striation analysis
We investigated mesoscale faults cropping out along the east coast of the Boso Peninsula and collected about 1,400 fault-slip data in the Awa and Kazusa Groups. The result of the fault striation analysis is as follows; a vertical axial compression, N-S extension and NW-SE extension were detected from the upper Katsuura Formation to the Umegase Formation. In addition to the above-mentioned three stresses, we detected NE-SW compression from the Amatu Formation to the Kurotaki unconformity and an early stage extension from the Amatsu and Kiyosumi Formations. The clarified stress history is summarized as follows; the early stage extension before ~3 Ma, the NE-SW compression at 3-2 Ma, the NW-SE extension at 2-0.8 Ma, the N-S extension after 0.8 Ma and the vertical axial compression at the present.
The most important discovery of this study is that the compression was episodic from 3 to ~2 Ma. In this presentation, we discuss the relationship between the paleostress and the past position of the TTT junction.
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