Abstract

ORTIZ SUAREZ, Ariel et al. Basementgeology of the northwestern sector of Sierra de San Luis. Rev. Asoc. Geol. Argent. [online]. 2009, vol.64, n.3, pp.481-492. ISSN 0004-4822.

Although in the past few years numerous studies aboutthe geology of the basement of the Sierra de San Luis have been carried out,the majority of these have been focused on the southern region. In this studythe cartography of the different lithologies of the northern region basementhas been produced, establishing the relationships with well known units. Themetamorphic rocks are represented by the here called Las Higuerasmetamorphites, a sedimentary sequence with acid and intermediate volcanicintercalations, formed by pelites, graywackes and calcosilicatic rocks,metamorphosed under the conditions of the lowest subfacies of low pressurefacies amphibolites and affected by three deformation phases. In parts theserocks have suffered contact metamorphism produced by two different magmaticsevents. The protoliths of Las Higueras metamorphites show important analogieswith the San Luis Formation, which is described in the more southern areas. Theigneous rocks of the region correspond to the Quines tonalite and to thetonalites and monzogranites Potrero de Gutierrez. These bodies have beensubsequently intruded at the first metamorphic event and in a prior topartially contemporary manner at the second metamorphism. Judging by theirgeology and petrography, they show analogies to the Famatinian Ordovicianpreorogenic granitoids. El Hornito and La Poblacion granites have also beenrecognised, belonging to the denominated Famatinian post-orogenic granitoides,accompanied by numerous dykes of acid composition and of mafic dykes andenclaves.

Keywords : Sierras Pampeanas; El Hornito; Las Higueras; Famatinian.

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