| Text Description: |
A 5-10' thick dike cutting through the brecciated unit (sBA9) at Site 12. There is a 1-2 inch bake zone along the sides of the dike. Fine grained, vesicular, hypocrystalline, trachytic, seriate porphyritic with a matrix of mesostasis, opaque, clinopyroxene, olivine, plagioclase, orthopyroxene?, and glassy patches near vesicles. Plagioclase phenocrysts (An31-An59) are up to 4.25 mm, most are less than 0.9 mm and the larger grains may have sieve textured cores. Olivine phenocrysts are up to 1.25 mm with rare opaque inclusions. Orthopyroxene phenocrysts are up to 0.9 mm. Mode: 54.8% matrix, 34.5% plagioclase, 2.3% olivine, 2.1% clinopyroxene, 0.7% orthopyroxene, 5.6% vesicles. |