Fission‐track analysis of tertiary uplift history of granitic basement in the victoria range, west coast, new zealand

Abstract

Basement rocks of Paleogene sedimentary basins form the present physiographic highs on the West Coast of South Island, New Zealand. Apatite and zircon fission‐track ages of these basement rocks allow interpretations to be made on the depths of Paleogene burial and the Miocene uplift history of the Victoria Range. Apparent apatite fission‐track ages increase generally with elevation from 10 to 37 Ma. The ages of the high‐altitude samples represent uplift of rocks that have been only partially annealed during burial, while the young samples (i.e., those between 10 and 16 Ma) have been buried sufficiently deeply to allow annealing of all pre‐existing tracks. A rapid uplift pulse at this time reflects a major phase of compressional tectonics. Zircon ages also exhibit a general altitudinal correlation, but are not fully reset, and hence indicate that burial was to depths of less than 8 km. © 1991 Taylor & Francis Group, LLC.