Imaging exhumed continental and proto-oceanic crusts in the Camamu triple junction, Brazil
| Type | Article | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Date | 2023-06 | ||||||||||||||||||||
| Language | English | ||||||||||||||||||||
| Author(s) | Loureiro Afonso 1, 3, Afilhado Alexandra1, 2, Schnürle Philippe4, Evain Mikael4, Dias Nuno A.1, 2, Klingelhoefer Frauke4, Gallais Flora4, Pinheiro Joao Marcelo4, 7, Soares José Eduardo5, Fuck Reinhardt5, Cupertino J.A.6, Viana Adriano6, Corela Carlos1, Moulin Maryline4, Aslanian Daniel4 |
||||||||||||||||||||
| Author(s) | SALSA Team | ||||||||||||||||||||
| Affiliation(s) | 1 : Universidade de Lisboa, Faculdade de Ciências, Instituto Dom Luiz, Lisboa, Portugal 2 : Instituto Politécnico de Lisboa, Instituto Superior de Engenharia de Lisboa, Lisboa, Portugal 3 : Agência Regional para o Desenvolvimento da Investigação, Tecnologia e Inovação, Funchal, Portugal 4 : Laboratoire Géosciences Océan, Université de Brest, CNRS, Ifremer, UMR6538, F-29280, Plouzané, France 5 : Instituto de Geociências - Lablithos, Universidade de Brasília, Campus Darcy Ribeiro, 70910-900, Brasília, Brazil 6 : Petrobras, Cenpes Research Center, Rio de Janeiro, Brazil 7 : Universidade Federal de Santa Catarina, Departamento de Geologia, Brazil 8 : Departamento de Geofísica, Universidade Federal do Pampa, Campus Caçapava do Sul, 96570-000, Caçapava do Sul, RS, Brazil 9 : Laboratoire Géosciences Océan, UMR6538, Université de Bretagne Occidentale, Place Nicolas Copernic, 29280, Plouzané, France 10 : Géolittomer, LETG UMR 6554-CNRS, Institut de Géographie et d'Aménagement Régional de l'Université de Nantes, Campus Tertre, BP 81227, 44312, Nantes, CEDEX 3, France |
||||||||||||||||||||
| Source | Journal Of South American Earth Sciences (0895-9811) (Elsevier BV), 2023-06 , Vol. 126 , P. 104336 (24p.) | ||||||||||||||||||||
| DOI | 10.1016/j.jsames.2023.104336 | ||||||||||||||||||||
| Keyword(s) | NE Brazil, South atlantic ocean, Passive margins, Camamu triple poin, Wide-angle refraction seismic, PSDM, Crustal structure, Cretaceous breakup, Exhumed lower continental crust, SALSA | ||||||||||||||||||||
| Abstract | During the SALSA experiment, in 2014, twelve combined wide-angle refraction and coincident multi-channel seismic profiles were acquired in the Jequitinhonha-Almada-Camamu, Jacuípe, and Sergipe-Alagoas basins, NE Brazil. Profile SL09 images the Almada-Camamu basin and the São Francisco craton, with 18 four-channel ocean-bottom seismometers and 22 land stations. The datasets were forward modelled and combined with pre-stack depth migration to increase the horizontal resolution of the velocity models. Our results show that sediment thickness varies between 3.8 km in the oceanward part of the profile, 4.3 km in the Almada basin and 6.5 km in the Camamu basin. Crustal thickness at the north-western edge of the profile is of around 40 km, with velocity gradients indicating a continental origin. The Camamu basin, which corresponds to the triple junction between the aborted N–S oriented Tucano rift, the SW-NE oriented Jacuipe-Sergipe-Alagoas branch, and the N–S Jequitinhonha-Almada branch, presents two crustal layers: a very thin upper layer, about 1.5 km thick, which increases seawards to 3 km in the Almada basin, and an higher velocity (HV) layer (6.8–7.2 km/s) about 4 km thick. This lower layer gradually disappears in the Almada basin. At the south-eastern edge of the profile, the resolution is lower but the thickness of the crust seems to increase up to 5 km. Deep wide-angle reflections indicate upper mantle stratification. Crustal organisation and P-wave propagation velocities in the Almada and Camamu basins indicate a transitional crust domain of exhumed continental crust affinity. In the Camamu triple junction and beneath this thin exhumed continental crust, the HV layer may probably reflect intruded materials. No exhumed upper mantle is observed along the entire profile. The easternmost part of the profile may correspond to a proto-oceanic crust. Typical oceanic crust is never imaged along the 260 km-long offshore profile. |
||||||||||||||||||||
| Full Text |
|