Neoproterozoic low-pressure/high-temperature collisional metamorphic evolution in the Varzea do Capivarita Metamorphic Suite, SE Brazil: Thermobarometric and Sm/Nd evidence

P–T conditions and age of metamorphism in the Varzea do Capivarita Metamorphic Suite (VCMS) were determined to evaluate the tectonic evolution of the Dom Feliciano Belt, Sul-Rio-Grandense shield, South America. The first metamorphic event (M1) developed under high-amphibolite/granulite facies conditions, in a low-pressure/high-temperature baric regime. Pressures between 3 and 4 kbar and 730–800 °C were obtained using THERMOCALC on assemblages from migmatitic meta-mudstones, mafic and calc-silicate gneisses. M1 was followed by retrogression under static conditions (M2), with the development of reaction textures, possibly during the late stages of D1 deformation. Sm–Nd garnet-whole rock ages of 626–604 Ma are interpreted as recording crystallization during D1, assigning a Neoporterozoic age to the tectonic event that drove this metamorphism. M1–M2 metamorphic events were accompanied by E–W trending mineral and stretching lineations in the VCMS supracrustal and intrusive, calc-alkaline plutonic rocks. These structures are attributed to the collision between an active margin at the Brazilian side and the Kalahari Craton during late stages of amalgamation of W-Gondwana.