| Text Description: |
Approximately 30' thick flow underneath welded spatter at Gutbuster. There are least 3 flows in this package. Fine grained, vesicular, holocrystalline, porphyritic with a matrix of mesostasis, opaque, and plagioclase. Plagioclase phenocrysts (An46-An54) are up to 1.9 mm. Orthopyroxene phenocrysts are up to 0.45 mm and occasionally have opaque inclusions. Clinopyroxene phenocrysts are up to 0.25 mm; the crystals are strained and have undulatory extinction and bent cleavage planes. Olivine phenocrysts are up to 0.3 mm and are often skeletal. Mode: 77.7% matrix, 8.0% plagioclase, 0.2% clinopyroxene, 0.4% orthopyroxene, 13.7% vesicles. |