FN Archimer Export Format PT J TI Initiation of transform continental margins: the Cretaceous margins of the Demerara plateau BT AF Basile, Christophe Loncke, Lies Roest, Walter Graindorge, David Klingelhoefer, Frauke Museur, Thomas Heuret, Arnaud Lesourd-Laux, Thomas Vetel, William AS 1:1;2:2;3:3;4:4;5:3;6:3,4;7:5;8:1,6;9:6; FF 1:;2:;3:PDG-REM-GM-LAD;4:;5:PDG-REM-GM-LAD;6:PDG-REM-GM-LAD;7:;8:PDG-REM-GM-LAD;9:; C1 Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre, 38000 Grenoble, France 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 Ifremer, Centre de Brest, Institut Carnot – Ifremer EDROME, UR Géosciences Marines, BP 70, 29280 Plouzané, France University of Brest, CNRS, IUEM, Plouzané, France Université de Guyane, UMR 5243 Géosciences Montpellier, Campus de Troubiran, 97300 Cayenne, Guyane, France Total SA, Centre Scientifique et Technique Jean Feger (CSTJF), Avenue Larribau, 64018, Pau, France C2 UNIV GRENOBLE ALPES, FRANCE UNIV PERPIGNAN, FRANCE IFREMER, FRANCE UBO, FRANCE UNIV GUYANE, FRANCE TOTAL SA, FRANCE SI BREST SE PDG-REM-GM-LAD UBO UM GEO-OCEAN TC 0 UR https://archimer.ifremer.fr/doc/00748/86015/91259.pdf LA English DT Article CR DRADEM IGUANES MARGATS BO Pourquoi pas ? L'Atalante AB During the end of the lower Cretaceous, the connection between the South and the Central Atlantic accretionary axis led to the oblique opening of the Equatorial Atlantic, and to the separation of Africa and South America by alternating transform and rift margins. At the western end of the Equatorial Atlantic, we investigate the structure of the Cretaceous margins surrounding the Demerara plateau, north of French Guiana and Suriname. These margins were previously described as transform northward and divergent eastward. From the bathymetry and deep structures, we propose to divide the northern transform into three margin segments, with two transform segments separated by a divergent one. These two transform margins are very different, the north-western one being linear and associated with a steep and erosive continental slope, the north-eastern one consisting of several faults and ridges en echelon disposed. In between, the divergent margin appear to be a pull-apart basin localised by structures inherited from the previous Jurassic rifting. Additionally, the eastern divergent margin can have been localised by a thermal anomaly tentatively related to a hotspot. It is proposed that the deformation has been first localised in divergent (rift) basins, subsequently connected by transform faults. The structure of the transform fault varies with the offset between adjacent rift basins: large offset forms a linear transform, short (less than 200 km) offset forms en echelon structures. PY 2022 SO Geological Society, London, Special Publications SN 0305-8719 PU Geological Society of London VL 524 IS 1 DI 10.1144/SP524-2021-118 ID 86015 ER EF