The formation and recombination kinetics of [Si45−] centers in zircon

The radiation sensitivity, time stability and optical sensitivity of [Si 4 5− ] paramagnetic centers in natural zircon crystals, particularly those from the Late Neopleistocenic tuff of the Elbrus Volcano, have been studied. Optical bleaching was shown to result in the recombination of [Si 4 5− ] centers, while the concentration of centers increases in the absence of light due to the internal radiation background. The data obtained show the infeasibility of using [Si 4 5− ] centers in zircons as paleodosimeters in conventional dating methods using electron paramagnetic resonance (EPR) spectroscopy. New specific techniques need to be developed for EPR dating of zircons.