Granito São Domingos : registro de magmatismo pós-tectônico do orógeno intracontinental aguapeí - SW do Cráton Amazônico

Abstract

The São Domingos Granite is an intrusive body of the Guapé Intrusive Suite, located in the Aguapeí mobile belt, corresponding to a branch of the Sunsás Orogeny in SW Amazonian Craton. This body is considered as a batholith slightly elongated in the NE direction, which crops out over an area of ca. 150 km2. It is situated to the north of the São Domingos District, a municipality of the Jauru city, Mato Grosso State. It consists of hololeucocratic to leucocratic rocks ranging from pinky to pinky-gray. They are isotropic, ranging from equigranular to inequigranular grains, sometimes porphyritic and pegmatitic, classified as muscovite-biotite monzo to syenogranites. Sometimes they present garnet and monazite as primary accessory minerals. These features characterize them as S-type granites or Muscovite bearing Peraluminous Granitoides (MPG). The rocks contain high silica content, which characterizes them as very evolved, formed by high-K to shoshonitic, peraluminous, and ferrous calc-alkaline magmatism. A U-Pb age of 928 ± 5 Ma was obtained for one of the analyzed rocks, which agrees with previous U-Pb ages obtained for this granite. Sm-Nd analysis indicates a TDM model age of 1.58 Ga, and negative ND value (-2.90). These results demonstrate that the São Domingos intrusion corresponds to a post tectonic environment, related to the Sunsás orogeny, whose magmatic origin is associated to re-working of the ancient continental crust. Moreover, three different ETR patterns were found for these lithotipes, suggesting the generation of contemporaneous non-cogenetic magmas, involving distinct crustal sources.