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Andean geology 2011
Petrología y Estructura del Complejo ígneo-Metamórfico Aluminé, Provincia de Neuquén, ArgentinaKeywords: aluminé igneous-metamorphic complex, granitoids, metamorphic rocks, petrography, geochemistry, structure. Abstract: in the present contribution, the partial results of a detailed study of the magmatic, metamorphic and tectonic events developed in the aluminé igneous-metamorphic complex (aimc) are given. we define the aimc as the set of pre-andean and andean intrusive igneous and metamorphic rocks, outcropping in the área located between the aluminé, moquehue, ?orquinco and pulmarí lakes in the neuquén province, argentina. based on field and petrographic observations and geochemical characteristics, the granitic rocks forming part of the aimc have been classified as: 1. quartz diorites, 2. tonalites-granodiorites, 3. granodiorites and 4. granites. the geochemical parameters indícate that the defined lithologies derive from calcic to weakly calcalkaline magmas of metaluminous composition, typical of type i cordilleran batholiths associated with active continental margins. intercalated between the magmatic rocks, some outcrops of metamorphic basement composed mainly of schists, gneisses, amphibolites and scarce quartzose sandstones. andesites, tuffs and basalts cover in part the metamorphites and granitoids are exposed. the structure of the sector is characterized by the presence of three main sets of regional lineaments, with ne-sw, nw-se and n-s orientations. these directions coincide with the orientations of the three groups of penetrative foliations recognized in the magmatic rocks of the sector. on the basis of the petrographic-microstructural analysis and deformation mechanisms in minerals, at least two ductile deformation events were identified in the magmatic rocks of the área. field mapping and perrological-structural studies carried out so far, allow to differentiate two sectors with clearly contrasting characteristics. the north sector is characterized by the predominance of granitoids with andean ages (cretaceous or younger), whereas in the southern sector dominates the pre-andean granitoids of permotriassic-jurassic ages emplaced in a paleozoic basement. although the ge
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