Figure F9. Clay alteration overprinting (Thin Section 92; Sample 345-U1415N-4R-1, 12–13 cm [Piece 3]; under crossed polars). A. Chlorite (Chl) and prehnite (Pr) veins (v.) showing overprinting by clay (Cl) alteration with preservation of cross-fiber texture in olivine–sparsely phyric basalt. Box shows location of B. B. Chlorite vein with clay replacement and by an unfilled crack. Plagioclase (Pl) shows slight offset, suggesting that the crack acted as a transfer fracture; chlorite was injected in two parallel cracks that end on the fracture.
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