Isotopic study of igneous and metamorphic rocks of Comallo-Paso Flores, Río Negro, Argentina

Abstract

In the region that extends northwards from Comallo to Paso Flores in the Limay river (Fig.1), igneous and metamorphic rocks forming the Crystalline Basement of the area crop out. This basement outcrops discontinuously in the southwest of the North-Patagonian Massif and is referred to a Cushamen and Mamil Choique Formations. According to stratigraphic records, the youngest age of these rocks dates back to the Pre-Triassic and Upper Pre-Permian. The few isotopic ages previously obtained yielded significant values within the Carboniferous (K-Ar method) and Ordovician to Devonian (Rb-Sr).