| dc.description.abstract | Extensional stresses caused Africa and South America to break up about 130
Million Years. When Africa rifted away from South America, a large onshore triple
junction began at about 13° S and propagated northward. This triple junction failed and
created the Reconcavo-Tucano-Jupato rift (R-T-J), located in northeastern Brazil (north
of Salvador). The extensional stress that created this rift was caused by a change in the
force acting on the plate during the Aptian.
A series of offshore rifts also opened at this time, adjacent to the R-T-J rift; this
series of basins are referred to as Jacuipe, Sergipe, and Alagoas (J-S-A). The basins are
separated by bathymetric highs to the north and the south of the Sergipe-Alagoas basin.
The Sergipe-Alagoas basin has a Bouguer gravity anomalies more negative than -35
mGal, and the other two basins have values more negative than -100 mGal; the total
magnetic intensity is also about 60-80 nT higher in the Sergipe-Alagoas basin than the
surrounding basins. The gravity and magnetic values in the Sergipe-Alagoas basin,
when compared to the Jacuipe and the Sergipe-Alagoas basins, indicate that the depositional history and/or the formation of the Sergipe-Alagoas basin is different from
the other two basins.
This study was done by analyzing the gravity and magnetic anolamies in the
region, and comparing these anomalies to the stratigraphy of the basin. This research
has allowed the stratigraphy and structures of the Sergipe-Alagoas basin to be better
understood - the location of the Sergipe fracture zone will also be outlined. This study
provides a comprehensive view of the Sergipe-Alagoas basin and outlines a method for
using Gravity and Magnetics to better understand the stratigraphy and structure of the
Sergipe-Alagoas basin. | en |
