--> --> Diachronous Rift System Along Bahia State Coast — From Example of Extended Crust and Mantle Exhumation in the South Atlantic Ocean, Caixeta, José M.; Ferreira, Talles S.; Lima, Fabrizio D.; Francisco, Claudir; Dias, Anna Eliza S., #90100 (2009)
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Diachronous Rift System Along Bahia State Coast — From Example of Extended Crust and Mantle Exhumation in the South Atlantic Ocean

Caixeta, José M.1
 Ferreira, Talles S.1
 Lima, Fabrizio D.1
 Francisco, Claudir1
 Dias, Anna Eliza S.2

1E&P-EXP/IABCL/INTP, PETROBRAS, Rio de Janeiro, Brazil.
2
E&P-EXP/GEO/MSP, PETROBRAS,
Rio de Janeiro, Brazil.

Camamu and Almada basins are located in the southern Bahia state coast and have been prospected mainly in shallow water domains, in the proximal rift systems, which commonly present cenozoic marine rocks overlaying older proximal rifts (Valanginian to Barremian in age). Distal rift systems are believed to be found in ultra deep water portions, at the oceanic crust boundaries, once the continental crust opened in that position.

New interpretation of seismic data allowed the visualization of features typical of hyper-extended crust model, such as exhumed mantle. The interpretation of the exhumed mantle model is supported by new seismic data recently acquired in these basins, including 3D seismic survey and new gravimetric and Previous HitmagnetometricTop data. Deep discontinuities inside the continental crust can be easily traced and interpreted, and are related to the uplifted mantle material, supported by gravimetric anomalies consistently distributed in the transition between continental and oceanic crust along the northeastern portion of the brazilian atlantic margin. Other elements of this extended margin can also be envisaged such as seeward-dipping reflectors and distal rift systems. Such distal rifts are found in the vicinities of the oceanic/continental crust boundary with ages that should be younger than the proximal rifts.



AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil