Grenvillian basement and Famatinian events of the Sierra de Umango (29°s): a review and new geochronological data

Abstract

The Sierra de Umango (29°()(),S-68°40'W) was interpreted as part of a northernmost Grenvillian-age rocks of Laurentian-derived terrane, accreted to the southwestern margin of Gondwana. The most important tectono-metamorphic and magmatic processes related to this collision occurred along the N-S trending Famatinian orogen since the Ordovician to Devonian (e.g. Dalla Salda et al., 1992, 1998; Ramos et al., 1998; Astini, 1998; Casquet et al., 2001), overprinting the magmatic and metamorphic rocks already affected by previous Grenvillian history. In this paper we present new U-Pb ages that extends the outcrops of Grenvillian rocks to the north of the well known localities with Mesoproterozoic rocks, and also constrain the age of the subsequent overprinting events. The new ages together with the already existing data, allow us to understand the geological evolution of the Sierra de Vmango in relation to the Lower Paleozoic Famatinian Orogeny.