| Text Description: |
Approximately 15' thick flow from the top of the bottom andesite package at Site 1 in the Boyden Hills. Fine-grained, holocrystalline, intergranular, seriate to glomeroporphyritic with a matrix of mesostasis, plagioclase, clinopyroxene, opaque, and alteration. Plagioclase phenocrysts (An46-An65) are up to 1.2 mm; some have sieve textured cores; most have normal zoning with occasional oscillatory zoning, and occasionally include clinopyroxene. Orthopyroxene phenocrysts are up to 1.5 mm with rare clinopyroxene rims. Clinopyroxene phenocrysts are up to 1.25 mm. Mode: 52.5% matrix, 33.9% plagioclase, 1.5% clinopyroxene, 0.7% orthopyroxene, 6.3% alteration, 5.1% vesicles. |