Andesite pyroclast from ash flow deposit associated with flank collapse of ancestral Mt. Spurr Sample AF-06 of Nye and Turner (1990). Chem. sample from block from ash-flow tuff. Abundant. Photos. Top of section at first major bluff on Chakachatna R above confluence with Straight Cr. Matrix supported blocks to 1.5m. Blocks light-gray when fresh, weather to white in white matrix. In some places moderate sintering demonstrated by blocks breaking across block on same plane as matrix, rather than whole block separating from matrix. Orange and red-stained, fines-depleted gas escape pipes exist.
Petrology, geochemistry, and age of the Spurr volcanic complex, eastern Aleutian arc