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Figure F53. Thin section photomicrographs of basalt, Site U1376. Highly olivine-augite-phyric basalt from lithologic Unit 15 (A) under plane-polarized light and (B) with crossed polars (Sample 330-U1376A-8R-6, 136–140 cm; Thin Section 255). C. Hyaloclastite breccia from lithologic Unit 21 showing fresh basaltic glass shards with curved edges (Sample 330-U1376A-17R-1, 140–143 cm; Thin Section 262) (plane-polarized light). Homogeneity of the glass suggests fragments quenched very rapidly, and shape of shards suggests they are bubble-walled fragments. Voids between glass shards are unfilled. Darkening of glass around shard edges is due to numerous minute tubes formed by microorganisms. D. Orthopyroxene xenocryst surrounded by reaction corona composed of tiny crystals of clinopyroxene (Sample 330-U1376A-1R-4, 39–42 cm; Thin Section 234) (plane-polarized light). See Figure F51E for scanned image of archive-half interval shown here.

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