U-Pb ages of komatiitic rocks from Sierra de San Luis, Argentina

SATO, A.M.; GONZÁLEZ, P.D.; BASEI, M.A.S.; LLAMBÍAS, E.J.

Punta del Este, Uruguay

Simposio; V Simposium on Isotope Geology; 2006

One of the distinguishing features of the western region of Sierra de San Luis in the Sierras Pampeanas of Argentina is the occurrence of a 45 km long belt of mafic-ultramafic extrusive rocks that appear as scattered outcrops sharing the same structural and metamorphic evolution as the hosting Nogolí Metamorphic Complex. Being still unclear the precise timing of the protolith evolution and the first orogenesis affecting them - somewhere in the Proterozoic to the earliest Paleozoic -, the final orogenesis took place trçhrough the Early Paleozoic Famatinian orogeny, with emplacement of magmatic arc in a region subjected to low to high-grade metamorphism in a collisional regime. In this contribution we present results of U-Pb isotopic study on the mafic-ultramafic rocks and discuss their possible interpretations.