Figure F265. Comparison of background alteration and alteration halos at different levels in the dike complex. A. Background alteration with clinopyroxene partially altered to dusty clinopyroxene/actinolite on the left and unaltered clinopyroxene on the right (Thin Section 10; Sample 312-1256D-176R-1, 8–12 cm; 1276.18 mbsf) (plane-polarized light; field of view [FOV] = 1.12 mm). B. Same as A; cross-polarized light. C. More intense alteration with laumontite replacing plagioclase and actinolite replacing clinopyroxene (Thin Section 5; Sample 312-1256D-174R-1, 92–97 cm; 1266.32 mbsf) (plane-polarized light; FOV = 1.12 mm). D. Same as C; cross-polarized light. E. Background alteration with clinopyroxene completely replaced by actinolite (Thin Section 25; Sample 312-1256D-186R-1, 48–53 cm; 1319.98 mbsf) (plane-polarized light; FOV = 1.12 mm). F. Same as E; cross-polarized light. G. Highly altered basalt with clinopyroxene replaced by actinolite and plagioclase replaced by albite, prehnite, and actinolite (Thin Section 23; Sample 312-1256D-184R-1, 10–12 cm; 1314.60 mbsf) (plane-polarized light; FOV = 1.12 mm). H. Same as G; cross-polarized light. I. Background alteration (Thin Section 30; Sample 312-1256D-189R-1, 68–69 cm; 1334.58 mbsf) (plane-polarized light, FOV = 4.5 mm). Highly altered basaltic dike with clinopyroxene replaced by actinolite. J. Same as I; cross-polarized light. K. Hornblende-rich amphibole vein with light gray halo grading out into background alteration (Thin Section 32; Sample 312-1256D-192R-1, 11–13 cm; 1348.41 mbsf) (plane-polarized light; FOV = 2.25 mm). L. Same as K; cross-polarized light.
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