Micro-textures of deformed gouges by friction experiments of Mont Terri Main Fault, Switzerland

Aoki, Kazuhiro ; Seshimo, Kazuyoshi ; Sakai, Toru*; Komine, Yusuke*; Kametaka, Masao*; Watanabe, Takahiro; Nussbaum, C.*; Guqlielmi, Y.*

Friction experiment was conducted on samples from the Main Fault of Mont Terri Rock Laboratory, Switzerland and then micro-textures of deformed gouges were observed using a scanning electron microscope JCM-6000 and JXA-8530F. Samples were taken at the depths of 47.2m and 37.3m of borehole BSF-1, and at 36.7m, 37.1m, 41.4m and 44.6m of borehole BSF-2, which were drilled from the drift floor at 260m depth from the surface. Friction experiment was conducted on above 6 samples using a rotary shear low to high-velocity friction apparatus at the Institute of Geology, China Earthquake Administration in Beijing at a normal stress of 3.95 to 4.0 MPa and at slip rates ranging 0.2 microns/s to 2.1mm/s. Cylindrical specimens of Ti-Al-V alloy, exhibiting similar behaviors as the host rock specimen, were used as rotary and stationary pistons of 40 mm diameter. A Teflon sleeve was used around the piston to confine the sample during the test. Main results are summarized as follows.