Shear-assisted water-fluxed melting and AFC processes in the foreland of the Early Paleozoic Famatinian orogen: petrogenesis of leucogranites and pegmatites from the Sierras de Córdoba, Argentina

In the Comechingones pegmatitic field, central Argentina, leucogranite and pegmatite bodies crop out in a relatively narrow (25 × 10 km) belt, were emplaced synkinematically with main deformational event of crustal-scale Guacha Corral shear zone during Early Ordovician (~ 475 Ma). These leucogranites pegmatites are geochemically evolved rocks high silica alkalis, low Fe2O3, MgO, TiO2 CaO, ASI values. The display quite variable Sr Nd isotope compositions (initial 87Sr/86Sr ratios from 0.7048 to 0.7170, εNd values + 2.0 − 3.1), some which do not overlap almost any other pre-Famatinian rock Sierras de Córdoba. major trace element geochemistry particular here explained by following processes: (1) water-fluxed partial melting amphibolites at P–T conditions generating currently unexposed granodioritic melts unradiogenic radiogenic values; (2) fractionation mostly plagioclase monazite leading close melts; (3) assimilation metasedimentary crustal isotopic signatures, modelled fractional crystallization processes. major, suggest derivation same protoliths Córdoba that assimilated melts. We propose feedback relationship among deformation, anatexis, magma evolution mass transfer context such foreland Famatinian orogen.