Figure F69. Olivine gabbro (Sample 345-U1415J-25G-1, 11–15 cm [Piece 2]; under crossed polars). A. Dramatic range in grain size with large (1–3 cm diameter) clinopyroxene oikocrysts, 0.5–1 cm diameter skeletal olivine crystals, and 0.5–5 mm long plagioclase crystals. Clinopyroxene oikocrysts contain chains of small plagioclase chadacrysts outlining areas of chadacryst-free clinopyroxene. Red boxes (tick marks show upward direction) indicate location and orientation of images in B–E. B. Large (1–5 mm) plagioclase crystals with deformation twinning. C. Fine-grained (<1 mm) annealed plagioclase crystals with gently curving grain boundaries. D. Narrow zone (0.5–2 mm wide) of submillimeter plagioclase and clinopyroxene crystals between two large clinopyroxene oikocrysts. Here, the grain boundaries are not annealed, and the tiny (<0.5 mm) fragments of clinopyroxene suggest this zone might be a recrystallized high-temperature near-solidus deformation zone between two clinopyroxene oikocrysts. E. Chains of small plagioclase chadacrysts outlining areas of chadacryst-free clinopyroxene.
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