Tectonic setting and sources of magmatism related to the southern Brazilian shear Belt

摘要: The Neoproterozoic-Cambrian Brasiliano/Pan-African orogenic cycle is represented, in southern Brazil, by arc and collisional settings, with very expressive granitic magmatism. post stage, 650-580 Ma, recorded extensive magmatism along major transcurrent shear zones that compose the Southern Brazilian Shear Belt. early post-collisional high-K, calc alkaline, found gently dipping zones; biotite-bearing granites granodiorites are most common rock types, often containing mafic micrpgranular enclaves. This immediately followed peraluminous two-mica leucogranites, emplaced either flat lying or steeply zones. next magmatic manifestation has a shoshonitic affinity within belt far from deformation sites, piercing through cratonic areas. Shoshonitic rocks range acid to basic, as extrusive plutonic terms. latest event silica- saturated alkaline magmatism, occurring outside belt. It controlled structures, discordantly intrusive previous types. Metaluminous biotite widespread, coeval basic of mildly affinity. acted conduit for magmas also promoted decompression shallower mantle levels, reactivating sources previous, calc-alkaline, pre-collisional role previously modified wedge generation postcollisional here emphasized over contribution crustal melting processes.