Study of fault evolution based on texture and chemical analyses of fault gouge; Case study of the Byobuyama fault, Gifu prefecture, central Japan

Katori, Takuma*; Kobayashi, Kenta*; Niwa, Masakazu   ; Shimizu, Mayuko   ; Komatsu, Tetsuya  ; Yasue, Kenichi; Horiuchi, Yasuharu

We performed structural analyses and XRD, XGT and EPMA analyses of fault rocks of the Byobuyama fault to reconstruct the history of the fault activity at shallow depth, as a case study for improving research technique to reveal the history of active faults. The results show that fault gouge zone along the fault has experienced activities of several stages under different stress, and significant differences in the deformation and alteration mechanism exist between these stages. Especially, the flow deformation of the fault gouge indicates that a large amount of fluid was present during the deformation. Abundance of illite infers that such fault gouge was formed by relatively high temperature fluid. In addition, eluviation structure of albite may indicate a deformation under environment such as to promote reaction solution. In this presentation, we discuss the vicissitudes of deformation and alteration mechanism in the fault gouge along the Byobuyama fault.