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Imaging early oceanic crust spreading in the Equatorial Atlantic Ocean: insights from the MAGIC wide-angle experiment

2021-11Journal article Restricted access
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dc.contributor.authorMoulin, Maryline
dc.contributor.authorSchnurle, Philippe
dc.contributor.authorAfilhado, Alexandra
dc.contributor.authorGallais, Flora
dc.contributor.authorDias, Nuno
dc.contributor.authorEvain, Mikael
dc.contributor.authorSoares, José
dc.contributor.authorFuck, Reinhardt
dc.contributor.authorNeto, Otaviano da Cruz Pessoa
dc.contributor.authorViana, Adriano
dc.contributor.authorAslanian, Daniel
dc.contributor.authorTeam, MAGIC
dc.date.accessioned2021-08-27T12:50:36Z
dc.date.available2021-08-27T12:50:36Z
dc.date.issued2021-11
dc.description.abstractDuring 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.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationMOULIN, Maryline; [et al] – Imaging early oceanic crust spreading in the Equatorial Atlantic Ocean: insights from the MAGIC wide-angle experimente. Journal of South American Earth Sciences. ISSN 0895-9811. Vol. 111, (2021), pp. 1-20pt_PT
dc.identifier.doi10.1016/j.jsames.2021.103493pt_PT
dc.identifier.issn0895-9811
dc.identifier.urihttp://hdl.handle.net/10400.21/13660
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherElsevierpt_PT
dc.relation.publisherversionhttps://reader.elsevier.com/reader/sd/pii/S0895981121003394?token=EC0A6F3DCA8F88143F87FDE100028DF3F097D13062060EBD92B21A826374100F96F8DA6DCB04D3286F76CE8DC4B452C0&originRegion=eu-west-1&originCreation=20210827101323pt_PT
dc.subjectEquatorial Atlantic Oceanpt_PT
dc.subjectBrazilpt_PT
dc.subjectPará-Maranhão-Barreirinhas-Ceará basinspt_PT
dc.subjectWide-angle seismicpt_PT
dc.subjectOceanic crustpt_PT
dc.subjectIntermediate domainpt_PT
dc.titleImaging early oceanic crust spreading in the Equatorial Atlantic Ocean: insights from the MAGIC wide-angle experimentpt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage20pt_PT
oaire.citation.startPage1pt_PT
oaire.citation.titleJournal of South American Earth Sciencespt_PT
oaire.citation.volume111pt_PT
person.familyNameMoulin
person.familyNameSchnurle
person.familyNameAfilhado
person.familyNameDias
person.familyNameEvain
person.familyNameFuck
person.familyNameAslanian
person.givenNameMaryline
person.givenNamePhilippe
person.givenNameAlexandra
person.givenNameNuno
person.givenNameMikael
person.givenNameReinhardt
person.givenNameDaniel
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person.identifier.orcid0000-0002-4387-5785
person.identifier.orcid0000-0003-1396-125X
person.identifier.orcid0000-0002-9394-606X
person.identifier.ridD-5242-2016
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rcaap.rightsclosedAccesspt_PT
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