Figure F271. A sequence of photomicrographs taken from the inner core of the alteration patch (A, B) to outside of the patch (G, H) (Thin Section 5; Sample 312-1256D-174R-1, 92–97 cm; 1266.32 mbsf). A. Epidote, magnetite, and euhedral quartz replaced by laumontite with porosity filled by late-stage prehnite (plane-polarized light; field of view [FOV] = 2.25 mm). B. Same as A; cross-polarized light. C. Epidote, later prehnite, and laumontite surrounded by early chlorite in alteration patch (plane-polarized light; FOV = 4.5 mm). D. Same as C; cross-polarized light. E. Highly altered dolerite with plagioclase replaced by epidote, and clinopyroxene replaced by actinolite (plane-polarized light; FOV = 1.12 mm). F. Same as E; cross-polarized light. G. Highly altered dolerite with laumontite replacing plagioclase, and actinolite replacing clinopyroxene (plane-polarized light; FOV = 1.12 mm). H. Same as G; cross-polarized light.
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