SHRIMP U-Pb age and high temperature conditions of the collisional metamorphism in the Várzea do Capivarita Complex: Implications for the origin of Pelotas Batholith, Dom Feliciano Belt, southern Brazil

摘要: Abstract The Varzea do Capivarita Complex is composed of pelitic gneisses with subordinate calc-silicate rock, marble and rare quartzite. It part the neoproterozoic Dom Feliciano Belt, in southern Brazil. are associated to veins tabular leucogranite bodies, which product anatexis gneiss. paragneisses tectonically juxtaposed orthogneisses Arroio dos Ratos Complex. This complex exposed as megaxenoliths granites Encruzilhada Sul Suite smaller fragments Quiteria Cordilheira Granites, all Pelotas Batholith. metamorphic foliation oriented N30°W, dips between 35 55° SW mineral lineation suborizontal rake ranging from 15° 30° down dip NW SE, suggesting deformation a transpressive system. Based on paragenesis garnet–cordierite–sillimanite-biotite, metamorphism occurred at 720–820° C pressure 8–9 kbar, characterizing it intermediate high temperature series. Zircon grains one sample garnet–cordierite–sillimanite-biotite gneiss peraluminous was dated by U–Pb SHRIMP method. paragneiss zircon yielded an age 619 ± 4.3 Ma interpreted main event, whereas igneous indicates that magma crystallization took place 620 ± 6.3 Ma. (S2) magmatic (S0) parallel each other, indicating they were formed during same event. suggests Capivarite generated leucogranites right after climax collisional metamorphism.