Journal
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Volume 88, Issue -, Pages 649-672Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jsames.2018.09.015
Keywords
South Atlantic ocean; NE Brazil; Sergipe-Alagoas basin; Passive margins; Wide-angle refraction seismics; Crustal structure; Tectonic inheritance
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Funding
- program Science without Borders of the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) from Brazil [233613/ 2013-7]
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The structure and nature of the crust underlying the Camamu-Almada-Jequitinhonha-Sergipe-Alagoas basins System, in the NE Brazilian margin, were investigated based on the interpretation of 12 wide-angle seismic profiles acquired during the SALSA (Sergipe ALagoas Seismic Acquisition) experiment in 2014. In this work, we present two 220-km-long NW-SE combined wide-angle and reflection seismic profiles, SL 01 and SL 02, that have been acquired using 15 ocean-bottom-seismometers along each profile, offshore the southern part of the Sergipe Alagoas Basin (SAB), north of the Vaza-Barris Transfer zone. The SL 02 has a 150-km long inland continuation with 20 land-seismic-stations until the Sergipano Fold Belt (SFB). Wide-angle seismic forward modeling allows us to precisely divide the crust in three domains: beneath the continental shelf, a similar to 100 km wide necking zone is imaged where the continental crust thins from similar to 35 km on the Unthinned Continental Domain, which displays a three-layered crust structure, to less than 8 km on the Oceanic Crust Domain. In the necking zone, the upper and the middle layers thin dramatically and almost disappear, while the Moho discontinuity shows clear PmPs. The Continental-Oceanic Crust Boundary (COB) is located at similar to 80 km from the coastline and is marked by intracrustal seismic reflectors and changes in the seismic velocity, showing a sharp transition. On profile SL02, the oceanic crust is perturbed by a volcanic edifice together with an anomalous velocity zone underneath the area.
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