Paleo-Mesoarchean crustal dynamics of the São José do Campestre Massif
metamorphic, mafic, sedimentary, thermodynamics, geochronology
The São José do Campestre Massif, in northeastern Brazil, represents one of the oldest crustal fragments of South America. This Archean crust was also reworked during the Mesoarchean, Paleo- and Neoproterozoic. This work focuses on supracrustal rocks aiming to constrain depositional ages, as well as the timing and conditions of the metamorphic overprints. The results of the first article indicate that these were overprinted at ca. 3.05, as well as 2.0 and 0.6 Ga. Considering the effects of multiple recrystallization events, these rocks are younger than 3.35 Ga. Similar events are also identified in the São Francisco, Kaapvaal and Dharwar Cratons, suggesting a common evolution in the Paleo-Mesoarchean. In terms of metamorphic events, preliminary modelling indicates the presence of low (>450° C) and high (>1100° C) thermobarometric ratios. If confirmed, these could be one of the oldest evidences for oceanic crust subduction and tectonic plates.