An example of in situ granite formation in the northern boundary of the Proterozoic Sergipano fold belt, NE Brazil: the Xingَ Complex

The Xingó Complex occurs as a 1000 km2 NE-SW strip in the northern limit of the Proterozoic Sergipano fold belt within the Pernambuco-Alagoas Median Massif. It is comprised of the following rock types: a) migmatites, metatexites with diatexite pods; b) coarse-grained granites compared to migmatites, as lenses parallel to the migmatite foliation, with restites composed of biotite+zircon+sphene+apatite+epidote and c) as stocks of medium-grained granites and fine-grained dikes, hololeucocratic (biotite < 5%), with minor amounts of tourmaline, epidote, garnet and fluorite. Some dikes, more enriched in biotite, show crenulated borders, suggesting intrusion during a migmatite plastic stage. anites are peraluminous, and show a narrow range in SiO2 (70–75%). The observed geochemical patterns and variations within the studied granites suggest an origin of succesive restite unmixing followed by homogenization and fractional crystallization. ngó Complex is an example of in situ granite formation during the Brasiliano (Pan-African) orogeny, possibly related to the collision between the Sergipano Belt and the Pernambuco-Alagoas Median Massif.