Vista Alegre Meta-Ultramaphic body: A key towards tectono-metamorphic evolution of the Araçuaí orogen high-grade core

• Published in: Journal of South American earth sciences 2018-11, Vol.87, p.42-52
• Main Authors: Fonte-Boa, Tobias Maia Rabelo, Couto, Marco Antônio, Novo, Tiago Amâncio, Pedrosa-Soares, Antônio Carlos
• Format: Article
• Language: English
• Subjects: Araçuaí orogen; High-grade metamorphic core; Meta-ultramafic body
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2017.12.001

The Vista Alegre Meta-Ultramafic body is part of a cluster of meta-ultramafic occurrences located in the internal tectonic domain of the Araçuaí-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 Araçuaí 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 Araçuaí-West Congo orogen. The posterior stabilization, in greenschist facies conditions, represents a metamorphic retrogression related to the thermal event during the post-collisional stage. •Geophysical and detailed mineralogical study a meta-ultramafic body.•Magnetic response indicates three portions instead of one deep continue body.•Microscope studies indicate a progressive metamorphic path.•MVI technique seem to be more representative for deformed rocks.