CONICET | Buscador de Institutos y Recursos Humanos

Geochronological data on the structural evolution of the Sierra de San Luis provides an important insight in the geodynamic history along the southwestern margin of Gondwana. In the Pringles Metamorphic Complex metamorphic fabrics (S1) were affected by two folding events related to the Ordovician approach of the Cuyania Terrane. Contemporary formations of high-temperature shear-zones record a prominent east-side-up displacement. Resumption of compression due to the Achalian collision with the Chilenia Terrane is accommodated by the reactivation of the Famatinian high-temperature shear zones at greenschist facies conditions. K/Ar Ms ages point to their activity up to the Late Devonian. Early Cambrian sedimentation is proposed for the psammopelitic precursors of the Pringles Metamorphic Complex suggestive of an entirely post-Pampean structural history. A Sm/Nd mineral isochron and published SHRIMP U/Pb zircon ages bracket the emplacement of mafic and ultramafic intrusions between 506 Ma and 478 Ma. A Late Cambrian emplacement of the crustal derived Paso del Rey pluton is suggested by a 207Pb/206Pb zircon age at 491 ± 19 Ma. K/Ar Hbl, Ms and Bt ages and some additional substantiation by Rb/Sr mica dating record cooling after the Famatinian metamorphic peak. Ms ages from large Ms-booklets suggest a common cooling of the complex at ~445 Ma, whereas normal sized muscovites from gneissic rocks (K/Ar ages at ~380 Ma) indicate slow cooling of the Pringles Metamorphic Complex with respect to the other basement domains. K/Ar Bt ages between 360 Ma and 340 Ma captured cooling below ~300°C of the basement. Differential cooling is interpreted to reflect the Achalian tectonic cycle as an event separated from the Famatinian process.