Petrologia das suítes paleoproterozoicas paciência e catolé da porção setentrional do Domínio Porteirinha (Minas Gerais)

Abstract

The Porteirinha Domain, constituted by tonalitic-trondhjemític-granodioritic (TTG) gneisses, which are migmatized and sometimes milonitized, is located in the extreme north of Minas Gerais and presents a geotectonic evolution that began in Arquean (3.37 Ma), having been reworked over geological time. Intrusive in this domain, the Paciência and Catolé magmatic suites, respectively of monzosyenitic and granitic composition, exhibit well preserved magmatic textures. The Paciência Suite (2.05 Ga) consists of a metaluminous silica saturated alkali-calcic to alkaline series. It is post-collisional to late orogenic related to the regional Rhyacian-Orosirian orogenesis. It consists essentially of monzonites and syenites of medium to coarse grain, with mineralogy composed basically of potassic feldspar, plagioclase, amphibole, biotite and some quartz. These rocks are derived from the fractional crystallization of a lamprophyric magma. The Catolé Suite (1.79 Ga), post-orogenic / anorogenic, is formed by peraluminous medium to fine grain granites, and mineralogy composed basically of quartz, microcline, plagioclase, biotite and muscovite. Classified as A1, the granites from the Catolé Suite apparently are related to fractional crystallization processes of intraplate OIB-like (ocean island basalts) basaltic magmas, related to the activity of a mantle plume responsible for triggering regional taphrogenetic processes at the beginning of the Statherian period.