| Text Description: |
Vertical sheeted dike, trending E-W cutting through the brecciated unit (sBA9) at Site 12. Fine grained, holocrystalline, seriate porphyritic with a matrix of mesostasis, opaque and plagioclase. Plagioclase phenocrysts (An30 - An57) are up to 1.7 mm and some have sieve textured zones; the larger sieve textured grains can be oscillatory zoned; the smaller grains tend to have normal zoning. Orthopyroxene phenocrysts are up to 2.5 mm and some have clinopyroxene rims (up to 0.2 mm thick) or opaque inclusions. Olivine phenocrysts are up to 1.6 mm, but most are altered to serpentine. Clinopyroxene phenocrysts are up to 0.15 mm. 44.9% matrix, 39.5% plagioclase, 0.5% olivine, 0.3% altered olivine?, 2.4% clinopyroxene, 7.4% orthopyroxene, 5.0% vesicles. |