Crustal Evolution and the Brasiliano Orogeny in Northeast Brazil

Northeast Brazil comprises two structural provinces defined by Almeida et al. (1981). To the north the Parnaiba province includes the São Luis craton as a probable remnant of the West Africa craton in Brazil (Hurley 1967) and the Gurupi belt (Hasui et al. 1984). Most of northeast Brazil belongs to the Borborema province (Fig. 1) which extends for about 400000 km2. The major tectonic feature of this province is a system of sinuous and branched, anastomosing shear zones, which divide the province into elongate domains that often differ in lithology, metamorphic grade and structure, suggesting large-scale relative displacements (Schobbenhaus et al. 1981).