| Text Description: |
Approximately 25’ thick,, plagioclase-phyric flow at Site 12. Fine grained, vesicular, hypocrystalline, intersertal, weakly intergranular, seriate to glomeroporphyritic with a matrix of brown glass, opaque, plagioclase, clinopyroxene and orthopyroxene. Plagioclase phenocrysts (An38 - An58) are up to 7.75 mm and often have sieve textured rims, pyroxene inclusions and complex zoning. Orthopyroxene phenocrysts are up to 2.0 mm and some have clinopyroxene rims (mainly on smaller grains); there are occasional sieve textured rims. Clinopyroxene phenocrysts are up to 0.7 mm and the largest grains have orthopyroxene cores. Olivine? phenocrysts are surrounded by small orthopyroxene crystals. 63.1% matrix, 26.7% plagioclase, 0.2% orthopyroxene, 5.7% altered phase, 0.2% alteration. |