Expressão gravimétrica e aeromagnética dos compartimentos e limites tectônicos da Província Borborema, Nordeste do Brasil

Abstract

Borborema Province (BP) has a very complex history, but up to now, few geophysical data have been used to constrain its evolution history. This paper presents the first integrated gravity/magnetic/geological data interpretation of the tectonic framework of the province. BP is a Proterozoic fold belt extended between the Sao Luis - West Africa and Sao Francisco - Congo/Kasai cratons. Currently, as a result of an increase in geochronologic data, there is growing evidence that its evolution has occurred by a mechanism of terrane collage. This evolution model suggests that large crustal blocks were put together during Meso and Late-Proterozoic events, resulting in crust growing by the arrival of pieces of crust or by the addition of new crusts. Interpretation of regional magnetic and gravity maps revealed the boundaries between crust blocks or compartiments inside BP. As result of the integrated interpretation, it is proposed that BP is formed by the union of at least 11 crust blocks. Boundaries between these blocks form long lineaments in NE-SE direction, in some cases showing vergences to E-W direction. The major block to the south of BP is the Sao Francisco Craton. The boundary between BP and the craton is still a controversial question, but the geophysical data suggest that N-S lineaments, which occur inside the craton, prolong below Riacho do Pontal and Sergipano hrust fold belts, which are part of BP. In this way, the plate associated to the craton lies beyond its geologically mapped north limit.