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Lithospheric structuration onshore-offshore of the Sergipe-Alagoas passive margin, NE Brazil, based on wide-angle seismic data

By Joao Marcelo Pinheiro, Philippe Schnurle, Mikael Evain, A. Afilhado, Flora Gallais, Frauke Klingelhoefer, Afonso Loureiro, R. Fuck, J. Soares, J. A. Cupertino, A. Viana, Marina Rabineau, Agnes Baltzer, Massinissa Benabdellouahed, N. Dias, Maryline Moulin, Daniel Aslanian, Laetitia Morvan, Jean-pierre Maze, Delphine Pierre, Mathilde Pitel-roudaut, I Rio, D. Alves, P. Barros Junior, Youssef Biari, C. Corela, Jacques Crozon, J. L. Duarte, Cecile Ducatel, C. Falcao, Philippe Fernagu, David Le Piver, Zohra Mokeddem, Pascal Pelleau, C. Rigoti, Walter Roest and Mickael Roudaut

Abstract

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 ∼100 km wide necking zone is imaged where the continental crust thins from ∼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 ∼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

Topics: South Atlantic ocean, NE Brazil, Sergipe-Alagoas basin, Passive margins, Wide-angle refraction seismics, Crustal structure, Tectonic inheritance
Publisher: 'Elsevier BV'
Year: 2018
DOI identifier: 10.1016/j.jsames.2018.09.015
OAI identifier: oai:archimer.ifremer.fr:57263
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