Lithospheric structuration onshore-offshore of the Sergipe-Alagoas passive margin, NE Brazil, based on wide-angle seismic data
|Author(s)||Pinheiro Joao Marcelo1, Schnurle Philippe1, Evain Mikael1, Afilhado A.2, Gallais Flora1, Klingelhoefer Frauke1, Loureiro Afonso3, Fuck R.4, Soares J.4, Cupertino J. A.5, Viana A.5, Rabineau Marina8, Baltzer Agnes7, Benabdellouahed Massinissa6, Dias N.2, 3, Moulin Maryline1, Aslanian Daniel1, Morvan Laetitia1, Maze Jean-Pierre1, Pierre Delphine1, Pitel-Roudaut Mathilde1, Rio I3, Alves D.3, Barros Junior P.7, Biari Youssef1, Corela C.3, Crozon Jacques1, Duarte J. L.3, Ducatel Cecile1, Falcao C.7, Fernagu Philippe1, Le Piver David1, Mokeddem Zohra6, Pelleau Pascal1, Rigoti C.7, Roest Walter1, Roudaut Mickael1|
|Affiliation(s)||1 : IFREMER, REM GM, Ctr Brest, F-29280 Plouzane, France.
2 : Inst Politecn Lisboa, ISEL, R Conselheiro Emidio Navarro, P-1959007 Lisbon, Portugal.
3 : Univ Lisbon, Fac Ciencias, Inst Dom Luiz, Ed C1,Piso 1, P-1749016 Lisbon, Portugal.
4 : Univ Brasilia, Inst Geociencias, Campus Darcy Ribeiro, BR-70910900 Brasilia, DF, Brazil.
5 : Petrobras SA, Cenpes Res Ctr, Rio De Janeiro, Brazil.
6 : Univ Bretagne Occidentale, Lab Geosci Ocean, UMR6538, Pl Nicolas Copernic, F-29280 Plouzane, France.
7 : Univ Nantes, Geolittomer, LETG UMR 6554, CNRS,Inst Geog & Amenagement Reg, Campus Tertre,BP 81227, F-44312 Nantes 3, France.
|Source||Journal Of South American Earth Sciences (0895-9811) (Pergamon-elsevier Science Ltd), 2018-12 , Vol. 88 , P. 649-672|
|Keyword(s)||South Atlantic ocean, NE Brazil, Sergipe-Alagoas basin, Passive margins, Wide-angle refraction seismics, Crustal structure, Tectonic inheritance|
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.