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Figure F59. One-wavelength gypsum plate added to a locally foliated cataclasite (Thin Section 77; Sample 345-U1415J-21R-1, 17–19 cm [Piece 4]). Polycrystalline prehnite clasts (CC1) in a cataclastic matrix (CC2) of prehnite (Pr) and chlorite are separated by chlorite-rich foliae. Matrix chlorite generally defines a preferred orientation producing an anastomosing network of northeast-trending foliae (C-F). These are cut by a set of north-northeast–trending chlorite veins also defining a preferred orientation (violet area in B) to produce phyllonitic bands (Ph). These phyllonitic shear zones are in turn cut by a prehnite vein. A. Plane-polarized light. B. Under crossed polars.

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