An Example of activity evaluation of minor crush zone including subparallel clay veins in granite near the Monju site

Shimada, Koji   ; Ishimaru, Tsuneari ; Sueoka, Shigeru   ; Terusawa, Shuji; Yasue, Kenichi; Niwa, Masakazu   ; Umeda, Koji

Diverse situation of outcropping crush zones around important building constructions need upgrading of activity evaluation method without the use of overlying sediments. The method using the cross-cutting relations among geologic features in basement rocks is promising. However, minor crush zones without cross-cutting relation are frequently observed. An activity evaluation of such minor crush zone was carried out in one outcrop. The confirmation of an extension of the crush zone, age estimation of young overlying sediments, comparison of sense of shear of clay vein, comparison of outcrop morphology with another crush zone, and clay grain-size measurement of the near active fault and the crush zone are carried out. The results suggest that the crush zone is not an active fault or a weak zone which slips accompanied with the active zone.