Compared structure and evolution of the conjugate Demerara and Guinea transform marginal plateaus
|Author(s)||Loncke Lies1, Mercier De Lépinay Marion1, Basile Christophe2, Maillard Agnès3, Roest Walter4, de Clarens Philippe5, Patriat Martin4, Gaullier Virginie6, Klingelhoefer Frauke4, Graindorge David7, Sapin François5|
|Affiliation(s)||1 : University of Perpignan Via Domitia, Centre de Formation et de Recherche sur les Environnements Méditerranéens (CEFREM), UMR 5110, 52 Avenue Paul Alduy, 66100 Perpignan, France.
2 : ISTerre, UMR-CNRS 5275, Observatoire des Sciences de l'Univers de Grenoble, Université Joseph Fourier, Maison des Géosciences, 1381 rue de la Piscine, 38400 St. Martin d'Hères, France
3 : GET, Observatoire Midi-Pyrénées, Université de Toulouse, CNRS, IRD, UMR 5563, 14, Avenue E. Belin, F31400 Toulouse, France
4 : Ifremer, Géosciences Marines, CS 10070, 29280 Plouzané, France
5 : Total SA, CSTJF, Avenue Larribau, 64000 Pau, France.
6 : University of Lille, CNRS, Univ. Littoral Côte d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F59000 Lille, France
7 : University of Brest, CNRS, IUEM, Plouzané, France
|Source||Tectonophysics (0040-1951) (Elsevier BV), 2022-01 , Vol. 822 , P. 229112 (21p.)|
|WOS© Times Cited||3|
|Keyword(s)||Transform marginal plateau, Passive margin, Volcanic margin, Atlantic, Demerara, Guinea|
The Demerara and Guinea plateaus are conjugate Transform Marginal Plateaus (TMPs) formed at the junction of the Jurassic Central Atlantic Ocean and the Cretaceous Equatorial Atlantic Ocean. We compare their structure and evolution through a combined industrial/academic seismic dataset tied by well data. We show that these TMPs record a complete evolution history from the Jurassic Central Atlantic to the Equatorial Atlantic breakup and seafloor spreading phases. Both plateaus first formed as volcanic margins displaying successive SDR wedges migrating towards the newly forming Central Atlantic domain. In this context, Demerara and Guinea, conjugates of the Bahamas, seem to have formed in relation to plume activity at the southern end of the Central Atlantic domain. Our dataset suggests that the Demerara and Guinea plateaus initially represented two distinct extrusive centres separated by a crustal basement high. Later, during the Cretaceous Equatorial opening phase, both plateaus separated in a transform mode following this discontinuity. Deformation is notably asymmetric during this phase: Aptian to Albian folding, strike-slip, transtensive deformation and complex vertical movements on the Demerara side and only minor deformation on the Guinean side, except on its divergent Sierra Leone termination. The deformation is sealed on both plateaus by a regional upper Albian erosion unconformity. Extensional reactivation occurs on the Guinea side (probably through a general collapse?). To conclude, this study provides new insights into the nature and origin of TMPs and the key tectono-sedimentary archives they may contain to understand the polyphase breakup conditions of Gondwana.