Edades U-Pb SHRIMP en circones de granitos peraluminosos de la Sierra de Pie de Palo, Sierras Pampeanas Occidentales, Argentina

RAMACCIOTTI, C.; BALDO, E.G.; CASQUET, C.

Congreso; XX Congreso Geológico Argentino; 2017

The Sierra de Pie de Palo, located in the Andean foreland basin, consists of a Mesoproterozoic basement and an Ediacaran to Cambrian cover, both overprinted by the Ordovician Famatinian magmatism and metamorphism. Mafic rocks and granitic magmatism attributable to the Famatinian orogeny are well exposed in the southeastern portion of the range. Two of these granitic bodies correspond to the Las Liebres mylonitic granite and the El Camperito mylonitic granite. They consist of dikes and elongated plutons with mineral and chemical composition assignable to S-type granites. Most zircons of these granites have cores and low luminescence overgrowths. The former could be xenocrysts (inheritance) or antecrysts. The low luminescence overgrowths are interpreted as igneous in origin and represent a crystallization age at ~470 Ma. The younger ages (~440 Ma) correspond to a lead loss event that occurred probably during late Famatinan ductile shearing. The pattern of inherited zircon ages of these granites is very similar to those of the Ediacaran Difunta Correa Metasedimentary Sequence suggesting that granitic magmas result from partial melting of that sequence.