Fission track dating of alluvial zircons and heavy mineral provenance in Northeast Tasmania

Three alluvial zircon concentrates from the Blue Tier region have been fission track dated in a heavy mineral provenance study of Cenozoic sediments in NE Tasmania. Zircons in one concentrate are euhedral and are fine grained (mostly 0.1 to 0.3 mm). Dating gave a combined age of 367 ± 15 Ma confirming their derivation from Upper Devonian granites. Zircons from the other concentrates are rounded and coarser-grained (mostly 2–5mm). They gave a combined age of 46.7 ± 0.6 Ma. This agrees with the K-Ar radiometric dates obtained from three Blue Tier basalts (Sutherland & Wellman, pers. comm.). Some of the geological implications of this study are outlined in this paper.