Late Neoproterozoic-Cambrian granitic magmatism in the Araçuaí orogen (Brazil), the Eastern Brazilian Pegmatite Province and related mineral resources

Abstract

The Araçuaí orogen extends from the eastern edge of the São Francisco craton to the Atlantic margin, in southeastern Brazil. Orogenic igneous rocks, formed from c. 630 to c. 480 Ma, cover one third of this huge area, building up the Eastern Brazilian Pegmatite Province and the most important dimension stone province of Brazil. G1 supersuite (630-585 Ma) mainly consists of tonalite to granodiorite, with mafic to dioritic facies and enclaves, representing a continental calc-alkaline magmatic arc. G2 supersuite mostly includes S-type granites formed during the syn-collisional stage (585-560 Ma), from relatively shallow two-mica granites and related gem-rich pegmatites to deep garnet-biotite granites that are the site of yellow dimension stone deposits. The typical G3 rocks (545-525 Ma) are non-foliated garnet-cordierite leucogranites, making up autochthonous patches and veins. At the post-collisional stage (530-480 Ma), G4 and G5 supersuites were generated. The S-type G4 supersuite mostly consists of garnet-bearing two-mica leucogranites that are the source of many pegmatites mined for tourmalines and many other gems, lithium (spodumene) ore and industrial feldspar. G5 supersuite, consisting of high-K-Fe calc-alkaline to alkaline granitic and/or charnockitic to dioritic/noritic intrusions, is the source of aquamarine-topaz-rich pegmatites but mainly of a large dimension stone production.

C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group), in the Southern São Francisco Basin, Brazil

“…This is in agreement with the restricted environment proposed by Paula- Santos et al (2015) during the late Ediacaran, which suggest a proximal source of the study area with strong influence of freshwater from East to West, and contribution of detrital sediments derived from the Araçuaí orogen. It also shows that the Araçuaí orogen would be built on the Eastern border of the São Francisco craton, which is consistent with geochronological data pointing to post-collisional Araçuaí super-suites (Pedrosa-Soares et al, 2011) as representative sources of the Sete Lagoas Formation sediments. Thus, Paula-Santos et al (2015) suggested that the Bambuí Group was deposited in a foreland basin in which a restricted epi-continental sea submerged the São Francisco Craton when the surrounding orogens were completely built.…”

Age, provenance and tectonic setting of the high-grade Jequitinhonha Complex, Araçuaí Orogen, eastern Brazil

“…930 -870 Ma event which gave rise to continental rift basins (Zadinian and Mayumbian groups) and anorogenic magmatism of the Salto da Divisa granites and Pedro Lessa mafic dikes (Machado et al 1989, Tack et al 2001, 2011a, Thiéblemont et al 2011, Babinski et al 2012; and (iii) a ca. 735 -675 Ma continental rifting event (Rosa et al 2007, Pedrosa-Soares et al 2011a) that evolved to a passive margin setting with seafloor spreading, forming a confined oceanic basin, that is, a large gulf partially floored by oceanic crust. The post-glacial, diamictite-free units of the Macaúbas Group represent the infilling of this Cryogenian passive margin to ocean basin system (Pedrosa-Soares et al 1998, 2008, 2011a, Queiroga et al 2007.…”

“…735 -675 Ma continental rifting event (Rosa et al 2007, Pedrosa-Soares et al 2011a) that evolved to a passive margin setting with seafloor spreading, forming a confined oceanic basin, that is, a large gulf partially floored by oceanic crust. The post-glacial, diamictite-free units of the Macaúbas Group represent the infilling of this Cryogenian passive margin to ocean basin system (Pedrosa-Soares et al 1998, 2008, 2011a, Queiroga et al 2007.…”

Magmatic garnet in the Cordilleran-type Galiléia granitoids of the Araçuaí belt (Brazil): Evidence for crystallization in the lower crust

“…1c) (Gonçalves et al, 2014 and reference therein). According to Pedrosa-Soares et al (2001) and Pedrosa-Soares et al (2011) the granitoids and the metasediments are grouped together into the granitic 1 (G1) supersuite and are thought to be related to the precollisional stages of the Brasiliano orogeny that build up the Araçuaí orogen (Pedrosa-Soares et al, 2001). The Eastern Domain is subdivided into the Nova Venecia complex composed of migmatites, granulites and granites (e.g.…”