Caracterização estrutural e petrológica de metatonalitos e metadioritos do Complexo Arroio dos Ratos na sua seção-tipo, região de Quitéria, RS

摘要: The Arroio dos Ratos Complex is part of the Pelotas Batholith basement in Sul-rio-grandense Shield. Geological and structural mapping its type-section, region Quiteria, RS, has led to discrimination so-called Association 1 (A1), consisting foliated tonalitic dioritic rocks discordantly intruded by compositionally similar ones. Their comprises calc-silicate gneisses, as well metavolcano-sedimentary rocks. A1 are medium- coarse-grained, garnet-bearing biotite metatonalites, mafic-rich, fine-grained metadiorites where garnet restricted most differentiated varieties. Field relations indicate that these varieties have coarser ones synplutonic dykes. granoblastic texture found both rock groups attributed their recrystallization under temperatures compatible with upper amphibolite granulite facies conditions. main foliation, S , NW- EW-striking, variation mainly effect F 2 folding, whose axes plunge low moderate angles towards WSW, coincides  the stretching lineation position. original orientation later fold effects being suppressed,  interpreted been sub-horizontal, shallow dip WSW. Sense movement determined from macro- micro-scale structures indicates top-to-E. metatonalites meta- peraluminous belong medium high-K calc-alkaline series. behavior major trace elements, together moderately fractionated REE-patterns, enrichment LREE relation HREE, this magmatism took place a mature continental arc environment, comparable other TTG associations. Preliminary data Paleoproterozoic age for information gathered paper enables comparison association Encantadas orthogneisses, although latter show stronger regional, orogenic metamorphism. Thus, interpreted represent more phase same magmatic protoliths were formed.