Long decollements and mud volcanoes: Evidence from the Barbados Ridge Complex for the role of high pore-fluid pressure in the development of an accretionary complex

Mud volcanoes in front of the Barbados Ridge accretionary complex, discovered in multichannel seismic reflection profiles, provide evidence of very high pore-fluid pressures in the sedimentary cover on the oceanic lithosphere that is being subducted beneath the Lesser Antilles island arc. These high pore-fluid pressures can be attributed to the load imposed on the sedimentary cover by the weight of the advancing accretionary wedge. They offer a mechanical explanation for the very wide decollement that separates the Barbados Ridge Complex accretionary wedge from undeformed sediments on the oceanic lithosphere beneath it. Changes in level of this decollement may be induced by local variations in pore-fluid pressure.