LAUSR

Abstract The Vista Alegre Meta-Ultramafic body is part of a cluster of meta-ultramafic occurrences located in the internal tectonic domain of the Aracuai-West Congo orogen in southeast Brazil. They consist of several small northeast-trending bodies hosted by an orthogneiss basement and metasedimentary package tectonized and intruded by granites during the Brasiliano orogenic cycle. To improve the existent models of the tectono-metamorphic evolution of the Aracuai orogen high-grade metamorphic core, we performed a geophysical and detailed mineralogical study of the meta-ultramafic body and its host rocks. The magnetic response indicates three relatively shallow portions instead of one deep continue meta-ultramafic body. These portions are interpreted as mega boudins aligned parallel to the regional foliation. The petrographic and mineral chemistry studies indicate a high-grade progressive metamorphic path followed by a retrograde process. The metamorphic peak must have reached granulite facies conditions related to the collisional stage of the Aracuai-West Congo orogen. The posterior stabilization, in greenschist facies conditions, represents a metamorphic retrogression related to the thermal event during the post-collisional stage.