El metamorfismo de la Sierra Chica de Córdoba (Sierras Pampeanas). Argentina

Abstract

Preliminary results on the regional metamorphism of the Sierra Chica (Sierras Pampeanas) are reported.
The work is based on a detailed textural and mineral study of high-grade cordierite-garnet metapelitic
migmatites of diatexitic type. Three events are recognized on the basis of garnet textural and chemical
zoning: M7 probably represents an older metamorphism and took place under subsolidus conditions;
M2 is synchronous to the main regional foliation (Sn+1). The peak of metamorphism was reached at this
stage under granulite facies conditions (P1= 5.7 ± O.4kb, T= 820 ± 25°C). This event is assigned to the
Pampean Orogeny; M3 represents a lower P-T event which is temptatively assigned to the uplift of the
previously thickened continental crust. Registered P-T conditions for this retrograde event have been
determined at 4±0.5kb and 775 ± 75°C respectively.