Geochemical examination of obsidians from Newberry Caldera, Oregon

Abstract

Five obsidian flows located in Newberry Caldera, Oregon, were systematically sampled, and the samples have been chemically analyzed to examine the homogeneity in a single large flow and to study chemical differences among the flows. The largest flow, the Big Obsidian Flow, is highly homogeneous chemically. The five flows are very similar in composition, indicating a common source. Small chemical differences among the flows do exist, but the geologic cause of the differences is not determined.