New U/Pb and Pb/Pb zircon ages from the Biharia terrane rocks, Apuseni Mountains, Romania

The Biharia sequence from the Apuseni Mountains is a component of the Biharia Paleozoic terrane. The Biharia terrane probably evolved as an island arc between the Cadomian Somes and Baia de Aries terranes. A gneissic metagranodiorite associated with metabasites from the Valea Ierţii creek, was sampled for U/Pb and Pb/Pb zircon age determination. The zircons extracted out of the sampled rock were subjected both to dilution and evaporation methods. Dilution method offered Concordia intercepts at 227±23 Ma, 312±13 Ma, 465.7+8.4/-8.0 Ma, 703±21 Ma and 1604±45 Ma. Evaporated zircon grains gave 450±20 Ma and 543±17 Ma. The 227±23 Ma age and 312±13 Ma age have been interpreted as Pb loss due to the final effect of the Permian widespread magmatism and late Variscan anatexis respectively. The 465.7+8.4/-8.0 Ma and 450±50 Ma ages probably represent the protolith generation time. The 543±17 Ma is viewed as an inherited Cadomian age and the 703±21 and 1604±45 Ma might represent Cadomian and Saharan detrital zircon ages.