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The granulite-complexes of the Sierras de Córdoba, inside context of Sierras Pampeanas, expose the deeply-uplifted internal metamorphic zone of an early Cambrian orogen. One of the largest granulite-complexes in the north-central of Sierra de Comechingones consists mainly of a set of stromatic and diatexitic migmatites all derived from metasedimentary progenitors. Migmatites vary over a spectrum of morphologies ranging from patch, net, and stromatic metatexites to schollen-schlieren and nebulite diatexites with widespread interspersed anatectic granites. The granulite-complex subordinately includes amphibolites, marbles, serpentinized ultramafic rocks, and mafic plutonic rocks. Petrographic analysis, textural and structural interpretation, thermobarometric estimates, and inherited and metamorphic zircon dating reveal the metamorphic history of migmatites in the north-central part of the Sierra de Comechingones. Metastable preservation of kyanite reflects that migmatites were buried (0.69–0.78 GPa) and heated (~650 °C) along a prograde trajectory before the onset of extensive anatexis. Then migmatites were further heated to granulite-facies peak temperatures (≥800 °C) at similar pressures (0.77 ± 0.06 GPa) through the sillimanite stability field. Widespread partial melting of the metasedimentary sequence occurred during peak metamorphism. The entire granulite-complex cooled to temperatures below 550 °C and ascended to middle crustal depths (0.3–0.5 GPa). The prograde heating trajectory and decompression during uplift overcoming cooling and tectonic exhumation are compatible with a predominantly compressive deformation. Coeval widespread partial melting with contractional non-coaxial deformation triggered self-reorganization of anatectic melts giving rise syn-deformational migmatites. In all the analyzed migmatites, U–Pb zircon geochronology yields inherited ages corresponding to those of orogenic systems that characterize the West Gondwana supercontinent. Inherited ages show a polymodal distribution pattern with contributions from Neoproterozoic (551–734 Ma; i.e., Brasiliano - Pan-African) and Mesoproterozoic detrital zircons (850–1182 Ma; i.e., Grenvillian), and minor proportions of Paleoproterozoic zircon grains (1751–1839 Ma). Ages interpreted as metamorphism and anatexis suggest the development of a single metamorphic event and restricted anatexis to a relatively short period of about 15 Ma (ca. 540-525 Ma). Metamorphic ages associated with the metamorphic peak trajectory are related to the Cambrian Pampean Orogeny. • P-T- t path shows a clockwise evolution along a single metamorphic event. • U–Pb zircon geochronology constraints granulite-facies metamorphism to ~540-525 Ma. • Metamorphic evolution was coeval with a compressive non-coaxial deformation. • Metatexites and diatexites are Early Cambrian syn-deformational lithological products. [ABSTRACT FROM AUTHOR]

Four major igneous suites with different geochemical characteristics are identified in the accretionary complex of the Pampean orogeny from the southern Sierras de Córdoba, Argentina. Crystallization ages of gabbroic and trondhjemitic plutonic rocks are Early to Middle Cambrian. The plutonic suites include mafic to intermediate alkaline OIB-like rocks, mafic tholeiitic N-MORB rocks, transitional mafic rocks, and minor trondhjemitic rocks with adakitic geochemical signature. The multiple igneous suites are spatially and temporally related to what reveals simultaneous tapping of distinct source reservoirs with their respective melts remaining distinctive from extraction to emplacement at middle crustal depths. The alkaline mafic-intermediate rocks with OIB-like geochemistry were generated by the partial melting of an enriched or metasomatized mantle source. By contrast, tholeiitic mafic rocks with N-MORB geochemical signature came out from a depleted mantle source. Trace element abundances of the transitional mafic magmas reflect variable mixtures between OIB-like and MORB-type magmas. Trondhjemitic rocks exhibit geochemical features highlighting their parent melts formed by low degree melting of a metasomatized subducting oceanic crust. The most reliable setting to generate all these diverse magmatic suites at the same time is a convergent margin where the opening of a slab window followed ridge-trench interaction. A corollary is that widespread mafic magmatism enhanced heat advection and gave rise to extensive intra-crustal anatexis in an accretionary complex of crustal extension. • Coexistence of multiple magmatic sources in the Early to Middle Cambrian Pampean orogen. • Alkaline, transitional and N-MORB mafic magmas intruded into metamorphic sequences. • Trondhjemite silicic adakite magmas spatially associated with alkaline mafic magmas. • Atypical subduction environment driven by slab-window following active ridge subduction. [ABSTRACT FROM AUTHOR]