FN Archimer Export Format
PT J
TI Imaging early oceanic crust spreading in the Equatorial Atlantic Ocean: Insights from the MAGIC wide-angle experiment
BT 
AF Moulin, Maryline
   Schnurle, Philippe
   Afilhado, Alexandra
   Gallais, Flora
   Dias, Nuno
   Evain, Mikael
   Soares, José
   Fuck, Reinhardt
   da Cruz Pessoa Neto, Otaviano
   Viana, Adriano
   Aslanian, Daniel
AS 1:1;2:1;3:2,3;4:1;5:2,3;6:1;7:4;8:4;9:5;10:5;11:1,2,3,4,5,6,7,8;
FF 1:PDG-REM-GM-LGS;2:PDG-REM-GM-LGS;3:;4:PDG-REM-GM-LGS;5:;6:PDG-REM-GM-LGS;7:;8:;9:;10:;11:PDG-REM-GM-LGS;
C1 Ifremer, Department of Marine Geosciences, BP 70, 29280, Plouzané, France
   ISEL - Instituto Superior de Engenharia de Lisboa, Lisboa, Portugal
   IDL – Instituto Dom Luis, Lisboa, Faculdade das Ciências da Universidade de Lisboa, 1749-016, Lisboa, Portugal
   Instituto de Geociências – Lablithos, Universidade de Brasilia, Campus Darcy Ribeiro, 70910-900, Brasilia, Brazil
   Petrobras S.A., Research Center, CENPES, PROFEX, Rio de Janeiro, Brazil
   LETG-Nantes Geolittomer, Université de Nantes, Campus Tertre, BP 81227, 44312, Nantes Cedex 3, France
   IUEM, Domaines Océaniques, CNRS, 29280, Plouzané, France
   Departemento de Geofisica, Universidade Federal de Pampa, Campus Caçapava do Sul, 96570000, Caçapava do Sul, RS, Brazil
C2 IFREMER, FRANCE
   ISEL, PORTUGAL
   UNIV LISBOA, PORTUGAL
   UNIV BRASILIA, BRAZIL
   PETROBRAS SA, BRAZIL
   UNIV NANTES, FRANCE
   UBO, FRANCE
   UNIV FED PAMPA, BRAZIL
SI BREST
SE PDG-REM-GM-LGS
UM LGO
IN WOS Ifremer UPR
   copubli-france
   copubli-europe
   copubli-univ-france
   copubli-int-hors-europe
   copubli-sud
IF 2.453
TC 4
UR https://archimer.ifremer.fr/doc/00709/82119/86901.pdf
LA English
DT Article
CR MAGIC
   SANBA
BO Pourquoi pas ?
   Le Suroît
DE ;Equatorial Atlantic Ocean;Brazil;Para-Maranhao-Barreirinhas-Ceara basins;Wide-angle seismic;Oceanic crust;Intermediate domain
AB During the MAGIC (Margins of brAzil, Ghana, and Ivory Coast) experiment, five combined wide-angle, and reflection seismic profiles were acquired in the Pará-Maranhão/Barreirinhas/Ceará basins northern Brazil. This is a pull-apart passive margin, with two strike-slip borders. The equipment deployed includes 143 sea-bottom seismometers (OBS), a 4.5-km seismic streamer, and a 7587-in3 airgun array. In this paper, we focus on the distal parts of three profiles, and one entire transverse NW-SE profile, located on the presumed Cretaceous oceanic crust. Forward modelling of these wide-angle data sets reveals an E-W lateral evolution of the oceanic crust spreading initiation with: 1) just after the so-called intermediate domain, 60 km-wide domain that consists of a 5-km-thick crystalline crust. The basement presents two layers characterized by high acoustic velocity. This domain is bounded to the NW by a NW-SE volcanic line (Volcano Alignment), and 2) a 5-km-thick oceanic crust consisting of two layers characterized by “normal velocities” spanning between the two main fracture zones that fringe the Pará-Maranhão-Barreirinhas-Ceará segment. Despite a similar thickness, these two sub-domains present different velocity distribution in their two layers. They are both overlain by 5.5 km of sedimentary deposits. Forward wide-angle modelling confirms that the seafloor spreading process was progressive, with firstly the emplacement of a proto-oceanic crust, and then a thin oceanic crust. The “proto-oceanic” crust presents a similar seismic velocity with the intermediate domain interpreted as exhumed lower continental crust except for the lower part where the intruded lower crust gives place to a very sharp Moho at the base of the proto-oceanic domain. By contrast, the thin oceanic crust domain has a lower velocity structure in its upper layer, that is interpreted as basalt and is absent in the proto-oceanic crust. This eastward evolution, as also observed in the Provençal Basin, and the Santos Basin, suggests the involvement of the lower continental crust in the first steps of seafloor spreading. 
PY 2021
PD NOV
SO Journal Of South American Earth Sciences
SN 0895-9811
PU Elsevier BV
VL 111
UT 000700220500001
DI 10.1016/j.jsames.2021.103493
ID 82119
ER

EF