granitóides neoproterozóicos, classificação tectónica, tipo de magmatismo
Abstract
The granitoids of the Neoproterozoic in the Paraíba do Sul belt in the State of Rio de Janeiro are classified according to their ages related to the recognized tectonic phases, their location in the different tectonic domains, the crustal level of emplacement, petrografic compositions and the tectonic environment. Three groups of granites are distinguished: Syn-F2, Syn-F3 and Syn-F4. The compositionally expanded syn-F2 granitoids, (e.g. tonalite/granodiorite/granite), with age about the 620 Ma., are comparable to the Cordilleran I-Type magmatism, emplaced at level of the crust from amphibolite/granulite facies, and their origin is related to a subduction zone below of the Paraíba of Sul belt, from SE to NW. The other syn-F2 are migmatitic S-type granitoids, linked to a continental collision event with age about the 600 Ma. The syn-F3 and syn-F4 groups are compositionally restricted (e.g. monzogranite and syenogranite dominantly) (-490 - 560 Ma), and their magmatism is considered to be Caledonian I-Type.
