P-T conditions of cataclastic deformation associated with underplating: An example from the Cretaceous Shimanto complex, Kii Peninsula, SW Japan

P-T conditions of cataclastic deformation associated with underplating in subduction zone are estimated from fluid inclusions within the post-melange veins in the Cretaceous Shimanto Belt, Kii Peninsula, SW Japan. Both cataclasite and post-melange veins cut the melange fabric and are distributed along the thrusts in duplex structure. The homogenization temperatures range from 200 (+/-10)degreesC to 270 (+/-42)degreesC corresponding to entrapment pressures over a wide range from 145 (+/-5) MPa to 304 (-20) MPa. Our results have important implications in evaluating the relationship between underplating processes by duplexing and coseismic deformation in accretionary complexes.