INSTITUTO SUPERIOR DE CORRELACION GEOLOGICA
Unidad Ejecutora - UE
Magmatismo granítico polifásico en la Sierra de Velasco, La Rioja, Argentina.
TOSELLI, A.J.; ROSSI, J.N.; ACEÑOLAZA, F.; BÁEZ, M.A.; GROSSE, P.; LÓPEZ, J.P.; SARDI, F.G.; BELLOS, L.I.; DE LOS HOYOS, C.
Acta Geológica Lilloana
Fundación Miguel Lillo
Lugar: Tucumán; Año: 2008 vol. 20 p. 60 - 60
The Sierra de Velasco is conformed by large, mainly granitic outcrops integrated by numerous plutons, with different compositions, intrusion levels, and ages, related to each other through milonitic zones or by intrusive relationships. The metamorphic country rock is represented by phyllites and quartzites of the La Cébila formation, at the northeastern flank of the range. Along the eastern flank of the range, hornfels formed by contact metamorphism with the granites are present, while at the northern tip of the range, tonalities porphyries, which are previous to the granite intrusions occur. The plutons conform three batholiths with different ages that are defined as: Punta del Negro and Patquía, of Ordovician ages, and Aimosgasta Batholith, of Carboniferous age. The Bazán and Aimogasta Batholiths are peraluminous, while the Patquía Batholith is metaluminous. The shapes of the plutons, as well as the structural characters and grade of deformation indicate the order of intrusive sequences that may have begun in the Ordovician and culminated in the Lower carboniferous, with deformation hasses during the Silurian and Devonian, as indicated by geochronological studies.