HP-LT assemblages and minerals are described for the first time in the Alpujarride nappes of the Central and Eastern Betic Cordilleras. These assemblages occur in Permo-Triassic metapelites and include ferro-and magnesio-carpholite, aragonite, kyanite and Mg-rich chloritoid. The estimated P-T conditions range from 4-5 kbar at 280-300 °C to 7-9 kbar at 450-500 °C. Hence, these nappes underwent HP-LT metamorphism (thermal gradient of 12-16 °C/km), just as did the underlying Nevado-Filabride units, prior to their low-to intermediate pressure evolution.
The Passa Tempo Metamorphic Complex is one of several metamorphic complexes that form the Archean sialic crust of the southern São Francisco Craton. It encompasses hypersthene-bearing gneissic rocks, with subordinate NW-or EW-trending mafic-ultramafic bodies and granodioritic to alkali-granitic, weakly foliated, and light-colored granitoids. These granitoids are the product of generalized migmatization that followed granulite-facies metamorphism. To determine the ages of the granulite-facies metamorphism and granitoid genesis, we obtained U-Pb ages on zircon extracted from the mesosome and leucosome of the migmatitic gneisses. For the mesosome, a discordia that intercepts Concordia at 2622 ± 18 Ma is interpreted as a minimum age for granulite-facies metamorphism. For the leucosome, the upper intercept of discordia at 2599 ± 45 Ma corresponds to migmatization and granitoid genesis. Contemporaneous metamorphism and magmatism have been documented elsewhere in the São Francisco Craton, especially in the southern portion, demonstrating vast and vigorous reworking of sialic crust by the end of the Neoarchean.
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