Time lag between metamorphism and crystallization of anatectic granites (Cordoba, Argentina)

SHRIMP and LA-ICP-MS analyses carried out on zircons from the Rio de los Sauces granite revealed their metamorphic and igneous nature. The metamorphic zircons yielded an age of 537 +/- 4.8 (2s)Ma that probably predates the onset of the anatexis during the Pampean orogeny. By contrast, the igneous zircons yielded a younger age of 529 +/- 6 (2s)Ma and reflected its crystallization age. These data point to a short time lag of ca. 8Myr between the High Temperature (HT) metamorphic peak and the subsequent crystallization age of the granite. Concordia age of 534 +/- 3.8 (2s)Ma, for both types of zircon populations, can be considered as the mean age of the Pampean HT metamorphism in the Sierras de Cordoba.