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 Diablillos Intrusive Complex (CID, by its Spanish name), outcrops in the Inca Viejo Range, Eastern Puna Austral, which record magma mixing process, during the Famatinian Arc evolution. This complex is formed by diorites, qz-diorites, tonalities, granodiorites and granites (syeno and monzogranites), intruding low- to medium metamorphic rocks.

The tonalites and granodiorites facies are hybrid components that resulted from mixing between the diorites and granites. In some cases, we distinguished a mechanic hybridization (mingling). Field relationships and petrography show successive dioritic magma pulses into a felsic magmatic chamber, with different degrees of crystallization and hybridization. Great varieties of magmatic textures were formed reflecting a complex evolution during the generation of magmas until their emplacement and final consolidation. In this scenario, slow cooling magmatic textures were identified (such as, ocelli quartz, mantled plagioclase, corroded K-feldspars, etc.) occurring at lower crustal levels, and rapid cooling textures (e.g. acicular apatite) taking place at intermediate-upper crustal levels. Magma mixing is probably the dominant magmatic differentiation process in the Inca Viejo range. The integrated results of field relations and petrography, allowed us, to draw a conceptual mixing model, showing the interaction between mafic and felsic magmas at different rheological stages. In this sense, the compositional variations observed in the Diablillos Intrusive Complex could be explained by mixing different proportions between felsic and mafic magmas.