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Figure F10. Close-up photograph and photomicrograph of highly porphyritic basalt from Unit 6. Red boxes show location of thin section and photomicrograph. A. Microcrystalline to fine-grained groundmass with plagioclase phenocrysts (<0.5 mm) (interval 336-U1382A-10R-2, 107–119 cm [Piece 10]). B. Thin section showing two domains separated by a dashed line, dividing a chilled margin domain on the right with hyalophitic and cryptocrystalline groundmass from another domain on the left with groundmass grain size increasing with distance from the glassy margin (red arrow) (thin section = 25 mm wide). C. Euhedral to subhedral glomerocryst of plagioclase and clinopyroxene (field of view = 5 mm; cross-polarized).

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