Diachronic collision, slab break-off and long-term high thermal flux in the Brasiliano-Pan-African orogeny: Implications for the geodynamic evolution of the Mantiqueira Province

The Mantiqueira Province in SE Brazil and Uruguay is a complex Brasiliano/Pan-African orogenic province that has recently been the topic of conflicting geodynamic models focusing the possibility of multiple collision events during the Ediacaran-Ordovician assembly of the Western Gondwana Supercontinent. A thorough compilation of recently obtained high-resolution U-Pb geochronology and geochemistry in the Mantiqueira Province provided the following results: (a) considering the entire orogenic system, the pre-, syn- and post-orogenic periods range from >670-595 Ma, 620-550 Ma and 560-490 Ma, respectively, and are coeval with the intrusion of 3 distinct magmatic sequences within each geographic segment of this large orogenic province, evolving from: (i) calc-alkaline, arc-related magmatism; to (ii) syn-orogenic, anatectic magmatism coeval with the metamorphic climax; to (iii) calc-alkaline/alkaline (including shoshonitic and A-type affinity) magmatism that reveal significant lower crust and mantle contribution; (b) progressively younger ages are present from south to north, irrespective of the orogenic period considered, implying that the different geographic sectors were, from south to north, diachronically amalgamated into the Mantiqueira Province. Results provide important evidence for the existence of a single diachronic collision event at 630-590 Ma, followed by the thermal climax at 615-560 Ma, slab break-off, asthenospheric upwelling and mantle underplating that sustained long-term high heat flux conditions until 540-490 Ma, when post-tectonic calc-alkaline/alkaline granitoids (probably admixed with small amounts of slab melts formed at depth) intruded the middle/low-crust magmatic and metamorphic sequences during the final stages of thermal and orogenic collapse of the Mantiqueira Province belts. (C) 2015 Elsevier B.V. All rights reserved.