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ESTRUTURA DO ESCUDO SUL-BRASILEIRO: UMA REVISÃO ATRAVÉS DE DADOS GRAVIMÉTRICOS E MAGNETOMÉTRICOS

1993; Sociedade Brasileira de Geologia; Volume: 23; Issue: 3 Linguagem: Inglês

10.25249/0375-7536.1993233201214

ISSN

2177-4382

Autores

STEPHEN E. HALLINAN, Marta Sílvia Maria Mantovani, WLADIMIR SHUKOWSKY, IRALDO BRAGGION,

Tópico(s)

Geography and Environmental Studies

Resumo

New gravity data in southern Brazil are combined with previous data in Brazil and Uruguay, permitting detailed analysis of the basement structure. The Brasiliano cycle tectonic frameworks suggested by previous geological and geophysical studies are tested. Pre-Brasilianp structure (Transamazonian cycle), however, is an importam and hitherto unstated source of lateral density contrast responsible for distinctive gravity discontinuities. Gravity anomalies associated with Mesozoic magmatism are also discordant within the Brasiliano structure, and can also be distinguished by strong accompanying magnetic anomalies. Individual blocks within the Rio de La Plata craton are recognised and a new block, the Paso de los Toros Block, is defmed. The continuation of the Rio de La Plata Craton into Brazil is challenged. The possibly related pre-Brasiliano Nico Perez Terrane (strongly reworked during the Brasiliano) forms the basement to the Rio Grande do Sul Shield, at least to the west of the Pelotas Batholith. Residual isostatic gravity anomalies suggest the continuation of the Ribeira Belt from Paraná State to Rio Grande do Sul. The Curitiba Massif, however, does not. The Luis Alves Complex does continue at least partially towards the south, but its presence beneath the Rio Grande do Sul shield cannot be demonstrated by gravimetric data. The Internai Domain of the Santa Catarina part of the Dom Feliciano Belt can be traced to the Costeiro Granitoid Belt to the north, and is tentatively proposed to lie off the eastern seaboard in Rio Grande do Sul and Uruguay, but is no longer thought to correlate with the Pelotas Batholith. In this scenario, could the Brusque Group metasediments be linked to the Rocha Group?

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