| Text Description: |
Agglutinated wall approximately 15’ above a thick pyroclastic flow at Site 7. Fine grained, vesicular, holocrystalline, seriate porphyritic with a matrix of mesostasis, opaque, plagioclase, orthopyroxene, clinopyroxene and minor alteration lining vesicles. Plagioclase phenocrysts (An36 - An62) are up to 2.88 mm and sieve textured zones are common; normal zoning is common and some grains have oscillatory zoning. An altered phase, now composed of olivine?, of iddingsite, serpentine ± opaque is present. Orthopyroxene phenocrysts are up to 0.98 mm, and occasionally have sieve textured zones. Clinopyroxene phenocrysts are up to 0.15 mm. Opaque phenocrysts are up to 0.1 mm, but most are matrix sized. |