Comparison of population and external detector method dating in epidote

Epidote fission-track dating (FTD) was performed through both population and external detector method (EDM) in five samples from the Mantiqueira Mountain range, southwestern Brazil. The ages obtained via population conducted to a weighted mean age of (114±19)Ma. In order to perform EDM dating, it was necessary to measure the efficiency factor (g) between muscovite mica and epidote. Three measurements were performed and the weighted mean g   value obtained was (0.57±0.03)(0.57±0.03). The weighted EDM age was (98±7)Ma. The population error magnitude occurs due to the existence of few useful epidote grains. EDM provides dating with fewer grains, however there are difficulties concerning etching anisotropy that should be regarded. Both dating methods agreed.