Tectonic evolution of the Juruena magmatic arc between the Aripuanã and Juruena rivers: northwest Mato Grosso State, Brazil

Abstract

The area of study is located in the southwest of the Amazon Craton, northwest of Mato Grosso State and it comprises a region between Aripuanã and Juruena rivers. This paper proposes a geotectonic evolutionary model of a single continental magmatic arc for this Paleoproterozoic segment; its orogenesis starts around 1,820 Ma with subduction, oceanic plate consumption, crust generation followed by continental blocks oblique collision processes after approximately 160 Ma, resulting in the formation of the Juruena Magmatic Arc. The initial phase litotypes are represented by oceanic crust remnants from Bacaerí-Mogno Complex and sub-volcanic to volcanic rocks from Paranaíta Suite and Colíder Group respectively, which configures a marginal ridge. Southwestern, this belt is in contact with the Juruena Complex, a portion of the arc deformed in a ductile regime. This segment is composed by Vitória Suite, São Pedro and São Romão Granites and Vespor Mafic Suite. Volcanic rocks scattered in the complex, apparently filling retro-arc basins, are included in the Roosevelt Group. Post-collisional Type A granitogenesis, related to extensional tectonic, is represented by Serra da Providência Suite. The U-Pb LA-ICPMS geochronology results from two Paranaíta Suite samples, one Vitória Suite and one Vespor Mafic samples are 1,797 ±14, 1,769 ±17, 1,783 ±14 and 1,773 ±15 Ma, respectively. Ten rock samples were also examined by Sm-Nd method, resulting in TDM ages between 2.25 and 1.88 Ga and εND(t) values between -1,9 and +1,92. The isotopic results are compatible with the expected for the Juruena Magmatic Arc.