Timing of the HT/LP transpression in the Neoproterozoic Seridó Belt (Borborema Province, Brazil): Constraints from UPb (SHRIMP) geochronology and implications for the connections between NE Brazil and West Africa

Experimental anatexis, fluorine geochemistry and lead-isotope constraints on granite petrogenesis in the Seridó Belt, Borborema Province, northeastern Brazil

“…1) (Ebert and Claro, 1970;Jardim de Sá, 1994;Vauchez et al, 1995;Corsini et al, 1998;Dhuime et al, 2003;Baumgartner et al, 2006;Archanjo et al, 2013). The belt occurs to the north of the Patos shear zone and has been recognized as a transpressional tectonic structure controlled by shear zones striking northeast-southwest with east-west flexure toward the south (Archanjo and Bouchez, 1991;Corsini et al, 1991Corsini et al, , 1998Caby et al, 1995;Archanjo et al, 2013). Thermobarometry of the metasedimentary rocks has revealed low-pressure and high-temperature conditions with an outer staurolite-andalusite zone, where T = 550°C and P = 0.20-0.25 GPa, and an inner sillimanite zone, where T = 650°C and P = 0.4 GPa (Lima, 1992;Cunha de Souza, 1996;Corsini et al, 1998).…”

“…U-Pb zircon ages indicate a first intrusive episode at 590 Ma with the emplacement of the mafic to intermediate rocks of the Tororó pluton. The emplacement of the nearby Acari pluton occurred at 575 Ma during the main dextral transpressive deformation (Leterrier et al, 1994;Jardim de Sá et al, 1999;Archanjo et al, 2013). In the Santa Luzia migmatitic dome, south of the Acari pluton, zircon from granitic neosome within the Caicó Complex yielded similar U-Pb ages and fabric patterns (Archanjo et al, 2013).…”

“…Chemical Geology 400 (2015) The Seridó Belt of northeastern Brazil hosts several intrusions with distinct chemical affinities: Neoproterozoic high-K calcalkaline granitoids and Cambrian peraluminous pegmatitic granites and zoned pegmatites (e.g., Ferreira et al, 1998;Nascimento et al, 2000;Neves et al, 2000;Hollanda et al, 2003Hollanda et al, , 2010Guimarães et al, 2004;Baumgartner et al, 2006). The emplacement of these rocks is strongly controlled by transcurrent shear zones that cross the Neoproterozoic metasedimentary sequences and their Paleoproterozoic orthogneiss basement at the Seridó Belt (e.g., Archanjo and Bouchez, 1991;Corsini et al, 1991;Archanjo et al, 1992Archanjo et al, , 2013Vauchez et al;. The very extensive plutonism suggests that there was a strong and areally significant heat source in the lower crust that could promote conditions appropriate for either fluid-fluxed or fluid-absent partial melting of the metasedimentary belt and basement orthogneiss (e.g., Barboza and Bergantz, 2000;Droop et al, 2003).…”

Correlations of some Neoproterozoic carbonate-dominated successions in South America based on high-resolution chemostratigraphy

“…600 -585 Ma; Hollanda et al 2010). However, newly reported U-Pb zircon ages for the Acari granite (577 -572 Ma) and Santa Luzia migmatite constrain the HT/LP metamorphism of the Seridó to 575 Ma (Archanjo et al 2013).…”

“…This belt was affected by a strong transpressional deformation, intrusion of voluminous granitic magmas, and reworking by transcurrent structures that imparted an N-NE trend to this belt. The original stratigraphic relationships have been obscured by intense deformation and this led to divergent interpretations of the sedimentation age, stratigraphy, and evolution of the supracrustal rocks, in spite of several geochronological, geochemical, and structural studies (Jardim de Sá et al 1988Caby et al 1995;Archanjo et al 2013;Van Schmus et al 2003;Hollanda et al 2015).…”