CONTRIBUI O DE UMA SE O GRAVIM TRICA

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Revista Brasileira de Geof´ısica (2011) 29(2): 309-329
© 2011 Sociedade Brasileira de Geof´ısica
ISSN 0102-261X www.scielo.br/rbg ˜ DE UMA SEC¸AO
˜ GRAVIME´ TRICA TRANSVERSAL
CONTRIBUIC¸AO
˜ LITOSFE´ RICA NA PORC¸AO
˜ SETENTRIONAL
AO ESTUDO DA ESTRUTURAC¸AO
DA PROV´INCIA BORBOREMA, NE DO BRASIL
Liliana Sayuri Osako1 , David Lopes de Castro2 , Reinhardt Adolfo Fuck3 ,
Neivaldo Ara´ujo de Castro4 e Jo˜ao Paulo Ara´ujo Pitombeira4
Recebido em 5 agosto, 2010 / Aceito em 14 junho, 2011
Received on August 5, 2010 / Accepted on June 14, 2011

ABSTRACT. This paper presents a 2.5D gravimetric model generated from 315 new gravity stations obtained along a NW-SE 750 km geophysical transect in the northeastern portion of the Borborema Province, NE Brazil. The regional and residual components of the gravity field were modeled separately. Modeling of the regional anomalies revealed a crustal thickness variation from 28 to 32 km, considering the average densities of about 2.8 g/cm 3 for the continental crust and 3.3 g/cm3 for lithospheric mantle. High frequency residual anomalies were interpreted on the density contrasts between a 10 km thick upper crust and a broad assembly of supracrustal covers and basement units, which show density values between 2.55 to 2.9 g/cm 3 . The current configuration of the Borborema Province lithosphere is clearly the result of the Mesozoic South American – African breakup of West Gondwana, which overprinted the Brasiliano-Pan African orogenic structures.
Keywords: gravimetric modeling, lithosphere, Borborema Province.

RESUMO. Este trabalho apresenta um modelo gravim´etrico 2,5D gerado a partir de 315 novas estac¸o˜ es gravim´etricas levantadas ao longo de uma sec¸a˜o transversal
NW-SE com 750 km de extens˜ao na porc¸a˜o setentrional da Prov´ıncia Borborema, NE do Brasil. A modelagem gravim´etrica foi aplicada separadamente nas componentes regional e residual do campo gravitacional. A modelagem 2,5D das