Granitoids Marking the End of the Brasiliano (Pan - African) Orogeny Within the Central Tectonic Domain of the Borborema Province

Abstract

The studied syenogranite and granodiorite intrusions have a similar U-Pb zircon age (ca 570 Ma). They are intruded in the Central Tectonic Domain of the Borborema Province, forming an S-type belt in relation to the Patos and Pernambuco Lineaments. The studied granitoids are clinopyroxene biotite leuco-syenogranites of the Solidão Pluton; amphibole biotite sienogranites from the Queimadas Pluton; biotite granodiorite and amphibole biotite granodiorite, which occur as dikes cutting the Itapetim Complex and leuco-syenogranites from the Serra Branca Pluton. They show geochemical data transitional between shoshonitic and alkaline series. Deep troughs at Nb, Sr, P and Ti and high LILE/HFSE ratios characterize the spiderdiagram patterns. The ÎNd (0.6 Ga) values are extremely negative (-11 to -16; except for the Itapetim dykes ~-3) and Nd model ages (T DM ) range from 2.0 Ga to 2.5 Ga (the Itapetim dykes ~1.4Ga). Biotites of the studied granitoids are Fe-rich with Fe/(Fe+Mg) ratios in the 0.62 to 0.84 range. Biotites from older granitoids (640 Ma -580 Ma) of the Pajeú -Paraíba Terrane, have Fe/(Fe+Mg) ratios < 0.60. The isotopic and geochemical data suggest that the studied granitoids correspond to a trans-alkaline, ferro-potassic plutonism, originated by partial melting of Paleoproterozoic and Mesoproterozoic crusts, emplaced during the final stage of the Brasiliano Orogeny in the Central Tectonic Domain of the Borborema Province.

Zircon Pb-Pb Geochronology of the Caruaru Area, Northeastern Brazil: Temporal Constraints on the Proterozoic Evolution of Borborema Province

“…Histograms of zircon U-Pb and 207 Pb/ 206 Pb ages for orthogneisses and granitoids in the central sector of Borborema province. Sources: Van Schmus et al (1995), Silva et al (1996), Da Silva Filho (1998, 2000), Guimarães et al ( , 2000, Melo (1998), Accioly (2000), Leite et al (2000), Brito Neves et al (2001a, 2001b, Sá et al (2002), Neves et al (present study). Dantas et al, 1998;Brito Neves et al, 2001b).…”

“…Recent works (Guimarães and Da Silva Filho, 2000;Almeida and Guimarães, 2002;Guimarães et al, 2002) reveal an increasing number of pre-transcurrent plutons and orthogneisses in the central portion of Borborema Province, the ages of which range from 645 Ma to 620 Ma (Fig. 4).…”

“…Microstructural evidence indicates deformation at lower metamorphic conditions in plutons dated at 570 Ma (Araújo et al, 1996;Guimarães et al, 2000;Almeida et al, 2002b;Fig. 4) than in those with ages in the 590-580 Ma range.…”

Neoproterozoic tectonic and magmatic episodes in the NW sector of Borborema Province, NE Brazil, during assembly of Western Gondwana

“…Geochronological and structural data in the southern part of the BP clarify the tectonomagmatic evolution in the Transversal zone and southern tectonic domains (Ferreira et al, 1998;Guimarães et al, 2000;Neves et al, 2000;Neves and Mariano, 1999). This paper presents the relationship between tectonic and magmatic events in the northwestern part of the northern tectonic domain and specifically the Médio Coreaú domain.…”

“…The tectonic fabric in granite plutons has been considered a crustal-scale deformation marker that defines the timing of orogenic events (Paterson et al, 1989;Fowler and Paterson, 1997;Brown and Solar, 1998;Heilbron and Machado, 2003) in a thrusting setting (Duguet and Faure, 2004), from the early collisional stage through the later or final transcurrent stage (Djouadi et al, 1997;Paquette et al, 1998;Ferré et al, 1998;Guimarães et al, 2000;Neves et al, 2000). Geochronological and structural data in the southern part of the BP clarify the tectonomagmatic evolution in the Transversal zone and southern tectonic domains (Ferreira et al, 1998;Guimarães et al, 2000;Neves et al, 2000;Neves and Mariano, 1999).…”