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A EVOLUÇÃO GEOCRONOLÓGICA DA CORDILHEIRA DO ESPINHAÇO; DADOS NOVOS E INTEGRAÇÃO

1979; Sociedade Brasileira de Geologia; Volume: 9; Issue: 1 Linguagem: Inglês

10.25249/0375-7536.19797185

ISSN

2177-4382

Autores

NEVES BENJAMIN BLEY DE BRITO, KOJI KAWASHITA, CORDANI UMBERTO GIUSEPPE, David Jaques,

Tópico(s)

Geochemistry and Geologic Mapping

Resumo

This paper presents and discursses some of the last geochronological determinations carried out on rocks of the Espinhaço Mountain Belt; by different radiometric methods. For the most part, the basement is composed of Archaean rocks, with formation of magmatites and granites during the Transamazonian cycle (2,0 b.y.). The geologic evolution of the Chapada Diamantina Group is proposed as follows: 1- At 1,7 b.y. formed the first sedimentary basins, associated with continental acid voleanism. 2 - The main stage of folding and epizonal metamorphism occured at approximately 1,2 b.y, with post-tectonic events until 1,0 b.y. These last ones include basicfissure volcanism and tectonic uplift. 3 - During the Brazilian cycle (650-400 m.a.) the tectonothermal phenomena have affected in several ways and with different intensity the age determinations of all geological units.

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