Abstract
Studies conducted over the last decade concerning the rocks that underlie the municipality of Salvador have shown a complex geological history with a great diversity of medium- to high-grade metamorphic lithotypes, deformed in several phases and frequently cut by tabular mafic dykes and irregular granitic bodies. The latter, which were the subject of this study, frequently outcrop along the coastline of Salvador and are classified petrographically as monzo-syenogranites. They are classified as subalkaline and peraluminous according to their geochemical data, and stand out for being enriched in light rare earth elements and having a strong negative Europium (Eu) anomaly. These rocks are produced from anatectic melts or through the interaction of mantle-derived magmas with crustal materials. The negative values of εNd(t) (-6.08) corroborate with the crustal character and in the diagrams of tectonic ambience, they are plotted in the field of post-tectonic granites. The Sm-Nd model age (TDM) around 2.9 Ga indicates a neoarchean source for these lithotypes, whereas their U-Pb zircon age (LA-ICPMS) of 2,064 ± 36 Ma is similar to the U-Pb (SHRIMP) and Pb-Pb (evaporation) ages for late-tectonic granites of the Itabuna-Curaçá-Salvador belt. Considering the results of recent studies in the area of Salvador, the monzo-syenogranites can be interpreted as late-tectonic intrusions, since they are affected by dextral shear zones correlated with the last stage of deformation registered in the granulites of Salvador.
Highlights
The relationships between magmatic bodies and deformational events are useful to unravel the complex interactions between tectonics and the processes of generation and emplacement of magmas
The granulitic rocks that outcrop in Salvador, state of Bahia, Brazil, are located nearby the confluence of two important tectonic macro-units of the São Francisco craton (SFC; Almeida 1977): the first one, with N45° trends, corresponds to the Salvador–Esplanada belt (SEB) of Barbosa and Dominguez (1996), and the second one, oriented N10°, corresponds to the Itabuna–Salvador–Curaçá belt (ISCB) of Barbosa and Sabaté (2002, 2004) (Fig. 1)
In the portion of the SFC that outcrops in the state of Bahia, high-grade metamorphic rocks occur in the area of Itabuna–Ilhéus, in the south, and in the area of Curaçá, in the north, comprising the Itabuna–Salvador– Curaçá block (ISCB) of Barbosa and Sabaté (2002, 2004)
Summary
The relationships between magmatic bodies and deformational events are useful to unravel the complex interactions between tectonics and the processes of generation and emplacement of magmas. The granulitic rocks that outcrop in Salvador, state of Bahia, Brazil, are located nearby the confluence of two important tectonic macro-units of the São Francisco craton (SFC; Almeida 1977): the first one, with N45° trends, corresponds to the Salvador–Esplanada belt (SEB) of Barbosa and Dominguez (1996), and the second one, oriented N10°, corresponds to the Itabuna–Salvador–Curaçá belt (ISCB) of Barbosa and Sabaté (2002, 2004) (Fig. 1) Both units show a complex evolutionary history (Barbosa and Dominguez 1996, Barbosa and Sabaté 2002, 2004, Delgado et al 2002), which makes it difficult to establish precise geotectonic models and the connection between these two units. The petrographic, petrochemical, geochronological, and isotopic data of these rocks are presented and discussed, aiming to contribute to the knowledge of their tectonic environment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
