STOCK ITAMBÉ: AN EXAMPLE OF “S-TYPE GRANITE” FROM THE ESTRELA DO SUL GRANITE SUITE, INTRUSIVE IN THE SOUTHERN PORTION OF THE BRASILIA BELT

Itambé Stock: an example of "S-type granite" from the Estrela do Sul Granite Suite, intrusive in the Southern portion of the Brasília Belt

Abstract

ABSTRACT: The rocks of the Itambé Granite were identified southwest of the municipality of Estrela do Sul in the state of Minas Gerais, in the southern sector of the Brasília Belt, intrusive in lithotypes of the metasedimentary sequence of the Araxá Group. It is one of the seven Neoproterozoic stocks of the Suite Estrela do Sul Granite. From the geological surveys in scale 1:25.000, it was identified a stock composed of monzogranitic rocks arranged in an oval shape of approximately 6.2 km². The outcrops are predominantly characterized in block and thickets, defined by equi- a inequigranular rocks of fine to coarse granulation, hololeucocratic, isotropic and identified in six facies composed predominantly of quartz, microcline, oligoclase, biotite, muscovite (I and II), corundum, garnet, tourmaline, monazite, opaque minerals (hematite and ilmenite) and secondary minerals (epidote, calcite, leucoxene, iron hydroxide and clay minerals). They are rocks with contents between 67 and 70% of SiO₂, high percentages of Al₂O₃ and K2O, in addition to high concentrations of Rb, Ba, Th, you and K and enriched in light rare earth elements in relation to heavy ones. They are peraluminous, sin-collisional, high potassium to shoshonitic leucogranite, with granite signature to two S-type micas, generated by the partial crustal fusion of metasedimentary rocks, deep crustal levels, associated with crustal thickening in a continental volcanic arc environment, associated with the end of the evolution of the Brasilia Orogenic Belt.

Keywords: Itambé Granite, Type S Granite and Estrela do Sul Intrusive Suite