| Text Description: |
Approximately 10' thick flow. Lowest flow in the bottom andesite package at Site 1 in the Boyden Hills. Fine grained, vesicular, diktytaxitic, hypocrystalline, seriate to glomeroporphyritic with a matrix of brown glass, opaque, plagioclase, clinopyroxene and alteration. Plagioclase phenocrysts (An38-An63) are up to 1.75 mm and commonly have sieve textured cores, overgrowth rims, and normal zoning; occasionally have oscillatory zoning and may be strongly resorbed with irregular shape. Clinopyroxene phenocrysts are up 2.2 mm and occasionally have orthopyroxene cores. Olivine phenocrysts are up to 1.0 mm and occasionally have minor alteration along the rim. Orthopyroxene phenocrysts are up to 1.4 mm and display clinopyroxene rims. |