Thermochronological analysis of the dynamics of the Southern Alps, New Zealand

Abstract

The isotopic ages of material exposed close to the Alpine fault in the Southern Alps, New Zealand, vary in a consistent fashion along the orogen. For the K-Ar system, muscovite and biotite ages display two distinct spatial trends that meet in the area of Fox Glacier, where a strong relationship is observed between K-Ar age and altitude. Excess argon is present in samples between Mount Kinnaird and Haast Pass in the southwest of the Southern Alps, giving unrealistically old, inconsistent K-Ar ages across this region. Incorporation of excess argon appears to be highly variable, however, and minimization of its influence on dynamical interpretations of thermochronology is possible through consi..