Zircon U-Pb SHRIMP dating of Palaeoproterozoic Isla Mala granitic magmatism in the Rio de la Plata Craton, Uruguay

An important event of K-rich granitic magmatism occurred at ca. 2.07 Ga in the Rio de la Plata Craton, Uruguay, as determined by U-Pb zircon SHRIMP ge ochronology of two Isla Mala Suite granitic rocks. Previous indications of Archaean ages are not confirmed. The absence of recrystallization or new zi rcon growth suggests that the investigated region of the craton remained un affected by major Meso- or Neoproterozoic orogenies, although less incense deformation may have occurred and remained unregistered in the zircons. (C) 2000 Elsevier Science Ltd. All rights reserved.