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

Granites that outcrop in the Achiras Complex, in the southern end of the Si erra de Cordoba (Argentina), were generated and emplaced at mid-crustal lev els during the orogenic evolution of the Sierras Pampeanas, Argentina. Thre e 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 i n 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 t he different granites may be explained by sequential partial melting at dif ferent crustal levels, with some variations of source rock compositions and melting conditions. The petrologic evolution of the Achiras Complex (metam orphism-deformation-anatexis) is likely to be the result of tectonic conver gence and thickening of the continental crust, during the Famatinian orogen ic cycle of the Sierras Pampeanas of Argentina. (C) 1998 Elsevier Science L td. All rights reserved.