THE AGE AND MODE OF FORMATION OF GAUSSBERG, ANTARCTICA

Abstract

Circumstantial evidence indicates that Gaussberg, an isolated, 370 m high volcanic cone on the Antarctic coast at 57 °S, 89 °E, is the product of subglacial eruption. The vesicular, highly potassic leucitite, of which Gaussberg is composed, has been dated by K-Ar and fission-track methods, the former being applied to leucite concentrates, the latter to glassy leucitite from the ropy-textured, outer rind of a pillow-like structure. The K-Ar geochronology yields an average date of 56 000 ± 5000 years, jwhich is interpreted as defining the time of Gaussberg's formation. The fission-track work yields a less precise date, which supports the K-Ar age estimate. These new age determinations indicate..