“…This is a first-order regional-scale petrological feature of the Ordovician arc, where an I-type dominated plutonic belt along side of an S-type dominated belt were developed (see Toselli et al, 1996;Rossi et al, 2002). Within the Sierras de Famatina, Los Llanos-Chepes-Ulapes, and Valle Fértil-La Huerta, the predominant igneous rocks are calc-alkaline metaluminous I-type granitoids, whereas weakly or strongly peraluminous felsic granitoids appear subordinate (Toselli et al, 1996;Pankhurst et al, 1998;Otamendi et al, 2009). The opposite case occurs in other ranges among which Sierras of Fiambalá, Capillita, Zapata and, in part, Velasco are outstanding examples (Toselli et al, 1996;Rossi et al, 2002).…”