Figure F48. Close-up photographs of a ductile shear zone in which the foliation orientation and foliation intensity changes from the upper left (undeformed; grade = 0.5) to lower right (porphryroclastic mylonite; grade = 4). Both true color (dark) and negative (light) images are shown for clarity. Lines on negative images define the local orientation of the foliation, which tracks the finite strain ellipse as the high-strain mylonite is approached. The shear sense from this fanning orientation is reverse (Ramsay and Ghram, 1970). In addition, the inset is an enlargement of the negative image (right) that shows porphyroclasts with sigma-shaped pressure shadows. As shown in the inset, the pressure shadows also indicate a reverse sense of shear. The mylonite is cut by two coarse-grained, undeformed pyroxenite veins (Px) (interval 209-1268A-15R-1, 1

Figure F48. Close-up photographs of a ductile shear zone in which the foliation orientation and foliation intensity changes from the upper left (undeformed; grade = 0.5) to lower right (porphryroclastic mylonite; grade = 4). Both true color (dark) and negative (light) images are shown for clarity. Lines on negative images define the local orientation of the foliation, which tracks the finite strain ellipse as the high-strain mylonite is approached. The shear sense from this fanning orientation is reverse (Ramsay and Ghram, 1970). In addition, the inset is an enlargement of the negative image (right) that shows porphyroclasts with sigma-shaped pressure shadows. As shown in the inset, the pressure shadows also indicate a reverse sense of shear. The mylonite is cut by two coarse-grained, undeformed pyroxenite veins (Px) (interval 209-1268A-15R-1, 1–22 cm).