Figure F286. Plagioclase alteration in gabbros. A. Plagioclase highly fractured and replaced by secondary plagioclase + minor chlorite + titanite, adjacent to an epidote-titanite-prehnite-minor chlorite vein, with fracturing parallel to the vein margin (Thin Section 71; Sample 312-1256D-215R-1, 84–88 cm; 1416.54 mbsf) (plane-polarized light; field of view [FOV] = 2.25 mm). B. Same as A; cross-polarized light. C. Plagioclase partially replaced by albite, pumpellyite(?), epidote, and minor prehnite (Thin Section 79; Sample 312-1256D-217R-1, 64–69 cm; 1422.24 mbsf) (plane-polarized light; FOV = 1.12 mm). D. Same as C; cross-polarized light. E. “Gray” plagioclase riddled with millions of tiny inclusions in linear arrays parallel to the twin planes (Thin Section 116; Sample 312-1256D-232R-2, 98–100 cm; 1494.96 mbsf) (plane-polarized light; FOV = 0.6 mm). Crystal rims are relatively inclusion free. F. Same as E; cross-polarized light.
Previous | Close | Next | Top of page