S-C fabrics developed in cataclastic rocks from the Nojima fault zone, Japan and their implications for tectonic history

S-C fabrics similar to those found in mylonites are observed in foliated ca taclastic granitic rocks from the Nojima fault zone, southwest Japan. The f oliated cataclastic rocks comprise cataclasite, fault breccia, gouge, and c rushing-originated pseudotachylyte. The S-C fabrics observed in these catac lastic rocks involve S-surfaces defined by shape preferred orientation of b iotite fragments or aggregates of quartz and feldspar fragments, and C-and C'-surfaces defined by microshears and shear bands, respectively, where fin e-grained material is concentrated. Striations on the main fault plane are oriented parallel to the cataclasite lineations. A significant microstructu ral difference between the foliated cataclastic rocks and S-C mylonites is the absence of dynamically recrystallized grains in the foliated cataclasit es. The striations, cataclastic lineations, and the S-C fabrics in the cata clastic rocks formed from the late Tertiary to the late Holocene indicate t hat the Nojima fault zone has moved as a dextral strike-slip fault, with a minor reverse component since it formed. S-C fabrics in cataclastic rocks p rovide important information on the tectonic history and are reliable kinem atic indicators of the shear sense in brittle shear zones or faults. (C) 20 01 Elsevier Science Ltd. All rights reserved.