| Text Description: |
Top flow in the upper andesite package at Site 1 in the Boyden Hills. Fine-grained, vesicular, hypocrystalline, intersertal, intergranular, porphyritic to glomeroporphyritic with a matrix of brown glass, opaque, plagioclase, clinopyroxene and orthopyroxene?. Plagioclase phenocrysts (An42-An61) are up to 3.07 mm and oscillatory zoning is common; occasionally there are sieve textured zones. Orthopyroxene phenocrysts are up to 2.75 mm and have occasional altered patches, melt inclusions, olivine? or clinopyroxene? inclusions and some have thin clinopyroxene rims. Clinopyroxene phenocrysts are up to 1.02 mm. Mode: 55.9% matrix, 25.5% plagioclase, 1.0% clinopyroxene, 4.7% orthopyroxene, 12.9% vesicles. |