Deep structure of the Demerara Plateau: From a volcanic margin to a Transform Marginal Plateau

The Demerara Plateau (offshore Suriname and French Guiana) is located at the junction of Jurassic Central Atlantic Cretaceous Equatorial Oceans. study its crustal structure fundamental to understanding tectonic history, relationship with adjacent oceanic domains enlightening formation Transform Marginal Plateaus (TMPs). This presents two wide-angle seismic velocity models from MARGATS cruise experiment, composite reflection lines. plateau itself characterized by a 30 km thick crust, subdivided into three layers, including high lower crust (HVLC). velocities gradients do not fit values typical continental but could volcanic margin or Large Igneous Province (LIP) type crusts. We propose that the, possibly continental, intruded magmatic material upper layer likely composed extrusive rocks same origin, forming seaward dipping reflector sequences tilted west. SDR complex was emplaced during hotspot related rifting preceding opening North present-day western plateau. internal limit corresponds future eastern margin. would therefore be an inherited boarding Atlantic. reworked complex, creating northern transform divergent along also highlights major contribution thermal anomalies such as hotspots superposed phases in history TMPs, which share great number characteristics Demerara.