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VERGÊNCIA CENTRÍFUGA RESIDUAL NO SISTEMA DE DOBRAMENTOS SERGIPANO

1977; Sociedade Brasileira de Geologia; Volume: 7; Issue: 2 Linguagem: Inglês

10.5327/rbg.v7i2.114

2317-4889

Benjamim Bley de Brito Neves, Alcídes N. Sial, José do Patrocínio Tomaz Albuquerque,

Geological and Geochemical Analysis

The Sergipean fold system, with a maximum width of 200 km, total lenght of 400 km, general NW-SE trend, total area of 45 000 km 2 , triangle-shaped, is located in the states of Sergipe, Alagoas and Bahia. Field relationships suggest bilateral symmetry for the whole system, with two fold belts, separated by an axial zone characterized by a number of calcalkaline intrusions and several exposures of the basement. The northern fold belt, south Alagoas, exhibits a psamitic-pelitic meta-sedimentary sequence partially migmatised, subordinate limestone, some magmatism' metamorphism of amphibolite facies predominating over greenschist one, and axial planes of folds with vergence towards the Pernambuco-Alagoas massif, to the north (eugeosynclinal development)' In the southern fold belt, in Sergipe, a carbonatic-pelitic miogeosynclinal sequence predominates. The metamorphism is of low-rank, greenschist facies, and folds show axial planes with vergence towards the Sao Francisco craton, to the south. A preliminary plate tectonic model for the evolution of the whole folding sysrem, involving collision of two rigid plates (the Pernambuco-Alagoas massif and the Sao Francisco craton) is discussed.