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O CINTURÃO METAVULCANOSSEDIMENTAR BRUSQUE E A EVOLUÇÃO POLICÍCLICA DAS FAIXAS DOBRADAS PROTEROZÓICAS NO SUL DO BRASIL: UMA REVISÃO

1991; Sociedade Brasileira de Geologia; Volume: 21; Issue: 1 Linguagem: Inglês

10.25249/0375-7536.19916073

2177-4382

LUIZ C. SILVA,

Environmental Sustainability and Education

A REVIEW.Some recent Sm-Nd, Pb-Pb and U-Pb isotopic ages obtained in metasediments and granites related to the Brusque Complex, just confirm a field chronology, based on regional geological surveys which permitted to antecipate, by almost a decade, the policyclical evolution of the Proterozoic terranes in Southern Brazil.A review of the field and petrological constraints wich led to this approach is herein presented.Major aspects emphasized are the characterization of two cycles of crustal extension, ensialic rifting, associated with: 1. shallow and deep water marine sedimentation, submarine mafic-ultramafic volcanism, possible ocean floor generation and consume (Brusque Complex) and; 2. continental and marine (deltaic) deposits, mafic to intermediate-and felsic-alkaline subaerial volcanism; "A"type plutonism (Itajaí-Campo Alegre basins).In the absence of appropriated isotopic refinement T based on circunstancial evidences -the age of the first rifting phase (Brusque) is inferred to be largely Early to Middle Proterozoic.The second phase (Itajaí-Campo Alegre) has an isotopic record in the Upper Proterozoic to Early Paleozoic interval.As a consequence, the evolution of the Brusque Complex favors "B" -like subduction models following the first Proterozoic crustal fragmentation.Finally, they are discussed the current attempts to establish direct correlations of the Brusque Complex with some Brasiliano belts from the Paraná Block and from abroad, specially with respect to the Pan-African.Western Damara Belt.