CONICET | Buscador de Institutos y Recursos Humanos

Near Huerta Vieja, on the eastern slope of Sierra de Comechingones, a body of stromatitic migmatites have textural evidence in their leucosomes and melanosomes indicating partial melting, with a strong superimposed postmigmatitic deformation. Primary and secondary structures were separated using structural analysis and petrographic criteria. The former is represented by stromatitic layering and the latter by structures developed during an intense postmigmatitic deformation, that yielded a banded fabric that looks like the primary stromatitic one. Cuspated and lobated forms, pointing to leucosome and melanosome-mesosome respectively, indicating viscosity contrast in between, are recognized and interpreted here like mullions structures produced in an early syn- to postmigmatitic deformation stage, after the solidification of the leucosome. The pervasive deformation was progressive, developing a composite foliation and intrafolial folds with a strong sillimanite lineation parallel to the B axis, in a simple shear regime at high-grade metamorphic conditions. Kynematic indicators, specially S-C fabric, a late extensional crenulation cleavage and mineral lineations, were used to deduce top to south-west movement.

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