DATING ZIRCON BY COMBINED USE OF FISSION AND ALPHA-TRACKS

A new approach to dating zircon by combining fission and alpha tracks is described. In this method (alpha track method), spontaneous fission tracks in a sample are counted routinely and alpha tracks originating from the sample are counted on a plastic track detector. Uranium cont ent of the sample is monitored based on the alpha track density and th e detection time. Radioactive equilibrium and equal Th/U ratios among samples are assumed. A comparison between the conventional fission tra ck method and the alpha track method has been made using age standard and other zircon samples. The results suggest that the alpha track met hod provides acceptable dating results when internal zircon surfaces a re used for track counts. The alpha track method should be beneficial to those who do not have close access to neutron irradiation facilitie s.