Abstract
The Taquaral Granite is located on southern Amazon Craton in the region of Corumbá, westernmost part of the Brazilian state of Mato Grosso do Sul (MS), near Brazil-Bolivia frontier. This intrusion of batholitic dimensions is partially covered by sedimentary rocks of the Urucum, Tamengo Bocaina and Pantanal formations and Alluvial Deposits. The rock types are classified as quartz-monzodiorites, granodiorites, quartz-monzonites, monzo and syenogranites. There are two groups of enclaves genetically and compositionally different: one corresponds to mafic xenoliths and the second is identified as felsic microgranular enclave. Two deformation phases are observed: one ductile (F1) and the other brittle (F2). Geochemical data indicate intermediate to acidic composition for these rocks and a medium to high-K, metaluminous to peraluminous calk-alkaline magmatism, suggesting also their emplacement into magmatic arc settings. SHRIMP zircon U-Pb geochronological data of these granites reveals a crystallization age of 1861 ± 5.3 Ma. Whole rock Sm-Nd analyses provided εNd(1,86 Ga) values of -1.48 and -1.28 and TDM model ages of 2.32 and 2.25 Ga, likely indicating a Ryacian crustal source. Here we conclude that Taquaral Granite represents a magmatic episode generated at the end of the Orosirian, as a part of the Amoguija Magmatic Arc.
Highlights
Several papers have shown the occurrence of Orosirian magmatism over an extensive area in southern Amazon Craton being recognized in the Rio Apa Terrane by Correia Filho et al (1981), Araújo et al (1982), Godoi et al (2001), Lacerda Filho et al (2006), Cordani et al (2010), Brittes et al (2013) and Plens et al (2013)
The basement underlying the Neoproterozoic sedimentary covers in the region of Corumba has been described by Araújo et al (1982), Del’Arco et al (1982), Godoi et al (2001) and Lacerda Filho et al (2006) as an ensemble of gneisses, amphibolites, metagranites and granodiorites grouped into the Archean Rio Apa Complex
Petrographic and geochronological data it is possible to redefine the basement in this region as a set of Orosirian batholitic granitic intrusions related to the Alumiador Intrusive Suite of Araújo et al (1982)
Summary
Several papers have shown the occurrence of Orosirian magmatism over an extensive area in southern Amazon Craton being recognized in the Rio Apa Terrane by Correia Filho et al (1981), Araújo et al (1982), Godoi et al (2001), Lacerda Filho et al (2006), Cordani et al (2010), Brittes et al (2013) and Plens et al (2013). Vargas-Mattos (2010) describe the occurrence of Orosirian calc-alkaline granitoids in the San Pablo Terrane in Bolivia. This work aims the understanding of magmatic and deformational evolution of the Taquaral Granite, and of the Orosirian magmatism in the southern Amazon Craton. Geologic and petrographic characterization were carried out as well as SHRIMP zircon U-Pb dating, geochemistry and Sm-Nd isotopic analyses in order to determine the petrogenesis, time of emplacement, and tectonic setting
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