Geology, mineralogy and geochemistry of syn-orogenic anatectic granites from the Achiras Complex, Cَrdoba, Argentina: some petrogenetic and geodynamic implications

Granites that outcrop in the Achiras Complex, in the southern end of the Sierra de Córdoba (Argentina), were generated and emplaced at mid-crustal levels during the orogenic evolution of the Sierras Pampeanas, Argentina. Three different igneous associations of anatectic rocks are distinguished: (1) peraluminous leucogranites, (2) biotite monzogranites, and (3) biotite±amphibole monzogranites. Leucogranitic sheets were generated and emplaced in a syn- to late-kinematic relationship with the main metamorphic fabric of the Achiras Complex. The biotite granites were emplaced as larger plutons, during a late-orogenic stage. Field and petrologic evidence suggest that the different granites may be explained by sequential partial melting at different crustal levels, with some variations of source rock compositions and melting conditions. The petrologic evolution of the Achiras Complex (metamorphism–deformation–anatexis) is likely to be the result of tectonic convergence and thickening of the continental crust, during the Famatinian orogenic cycle of the Sierras Pampeanas of Argentina.