Figure F28. A, B. Gabbroic (Domain 1) and troctolitic (Domain 2) domains (Thin Section 140; Sample 345-U1415P-22R-2, 113–115 cm [Piece 8]). Olivine gabbro has apparently intruded into the troctolite in this sample. Red rectangles in A mark the approximate location of the images in C–F. C, E. Alteration of plagioclase (Pl) in Domain 1. Plagioclase (Pl) is slightly fractured and altered to fine-grained prehnite (Pr) and chlorite (Chl) along these microfractures. Cpx = clinopyroxene, Serp = serpentine, Ca = carbonate. D, F. Alteration of plagioclase in Domain 2. Plagioclase is completely replaced by both fine- and coarse-grained prehnite as well as lesser amounts of chlorite and possible hydrogarnet. A, C, and D are under plane-polarized light; B, E, and F are under crossed polars.
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