HR: 1340h
AN: MR23B-1323    [Abstracts]
TI: The roughness of uni-axial tensile fracture and rock anisotropy in Inada granite
AU: * Fujii, Y
EM: fujii@fgi.or.jp
AF: Fukada Geological Institute, Hon-Komagome 2-13-12, Bunkyo-Ku, Tokyo, 113-0021, Japan
AU: Takahashi, M
AF: National Institute of Advanced Industrial Science and Technology, Tsukuba Central 7, Tsukuba, 305-8567, Japan
AU: Takemura, T
AF: National Institute of Advanced Industrial Science and Technology, Tsukuba Central 7, Tsukuba, 305-8567, Japan
AU: Lin, W
AF: Japan Agency for Marine-Earth Science and Technology, 200 Monobe-otsu, Nankoku, Kochi, 783-8502, Japan
AB: The roughness of uni-axial tensile fracture and rock anisotropy in Inada granite Yukiyasu FUJII, Manabu TAKAHASHI, Takato TAKEMURA, LIN Weiren Inada granite contains a lot of microcracks which are preferentially oriented along three mutually perpendicular planes (rift, grain, and hardway planes). These microcracks (fabrics) affect the physical properties of the granite. In this study, fractures parallel to each plane were produced by uni-axial tensile tests. The obtained fracture surfaces were analyzed by digital stereo-photogrammetry. From the results of fracture roughness, the fracture parallel to the rift plane is the smoothest, and the fracture parallel to the grain plane is smoother than the fracture parallel to the hardway plane. The mineral compositions are also different on the failed surfaces of different directions. The rift-parallel fractures have almost the same constituent mineral ratio as the parent rock. However, the grain-parallel fractures pass preferentially through feldspar grains, and contain less quartz grains as compared to the bulk composition of the parent rock. In addition, it is remarkable on hardway-parallel fractures. The difference of fracture roughness is proportional to the rock anisotropy, due to preferred orientations of pre- existing microcracks. The microcracks parallel to rift plane are the most pronounced, and microcracks parallel to grain plane are more pronounced than hardway plane. The difference of mineral compositions can be explained by the differece of the pre-existing intra-granular microcrack fabrics between quartz and feldspar. It is considered that the final fractures result from the development and coalescence of pre-existing microcracks along more or less a single plane.
DE: 5104 Fracture and flow
DE: 5112 Microstructure
DE: 8010 Fractures and faults
DE: 8025 Mesoscopic fabrics
DE: 8030 Microstructures
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting