Fission track annealing and age determination of epidote minerals

Abstract

The epidote group of minerals is well-suited for age determination by the fission-track method. The minerals occur in a large variety of rock types; fission tracks are readily etched in them; and epidote retains its tracks at high temperatures. No annealing of fission tracks in epidote was detected after 16 days at 600°C, whereas almost all tracks were annealed in 6 hours at 700°C. Extrapolation of the experimentally determined temperatures suggest that a temperature of 630°C would be required for 106 years to remove all tracks. Fission-track ages of epidote and allanite agree well with ages of coexisting minerals determined both by fission-track and other methods.