Los granitos del Paleozoico inferior de la sierra de Inca Viejo, Puna Austral: aspectos texturales de la mezcla de magmas y modelo petrogenético

Abstract

The granites of the Lower Paleozoic from the sierra de Inca Viejo, Puna Austral. Textural aspects of the mixture of magmas and petrogenetic model The Diablillos intrusive Complex which outcrops in the Inca Viejo Range, Eastern Puna Austral, record magma mixing process, during the Famatinian Arc evolution. This complex is formed by diorites, quartz-diorites, tonalites, granodiorites and granites (syeno and monzogranites) intruding low- to medium grade metamorphic rocks. The tonalites and granodiorites facies are hybrids that resulted from mixing between diorites and granites. In some cases, mechanic hybridization (mingling) was distinguished. Field relationships and petrography show successive dioritic magma pulses into a magmatic chamber of granitic composition, developing products with different degrees of crystallization and hybridization.In the context of a magmatic chamber, the different magmatic textures reflect a complex evolution from the generation of magmas until their emplacement and final consolidation. In this scenario, both slow cooling magmatic textures (such as, ocelli quartz, mantled plagioclase, corroded K-feldspars) as well as rapid cooling textures (e.g. acicular apatite) developed at lower crustal levels and intermediate-upper crustal levels respectively were identified. Magma mixing is probably the dominant magmatic differentiation process in the Inca Viejo range. The integrated results, allowed us to draw a conceptual mixing model, showing the interaction between mafic and felsic magmas at different rheological stages.Therefore the compositional variations observed in the Diablillos Intrusive Complex could be explained by mixing different proportions of felsic and mafic magmas.