THE FUSTER CASAS SEDIMENTARY TROUGH (EAST OF THE LANZAROTE AND FUERTEVENTURA CANARY ISLANDS, SPAIN)

The Atlantic margin between Africa coastline and the Lanzarote and Fuerteventura islands (Canary Islands) has a complex geological evolution that can be summarized in the following tectono-sedimentary stages: 1) Massie rift evolving from platform deposits into a thick saline basin towards the deep offshore; 2) Jurassic drift with development of three carbonate megasequences; their westward progradation promoted a large sedimentary crest parallel to current coastline that separated the oriental platform and the deep-water facies of the Faster Casas Trough; 3) Thin carbonate Berriasian-Valanginian sequence; 4) First episode of deltaic type sedimentation occurred in the Barremian to Album that promoted a first sedimentary bypassing and the remarkable E-W extension of he thick delta slope and its subsequent contraction toward west deep waters. This was linked to diapiric extrusions of Triassic salt that also promote the first structural deformation in deep water areas; 5) Late Cretaceous transgression and deposition of marine organic-rich facies; 6) Paleocene-Lower Eocene unconformity filling pre-existing topography (sag basin?) with presence of thin phosphatic facies evolving to thin turbiditic deposit; 7) Eocene to Miocene development of three main turbiditic intervals (Fuerteventura, Lanzarote and Hesperides fans) and associated incised valleys; 8) Miocene-Pliocene deposits characterized by limited thin sandy turbiditic channels and deep-water shales. Deposition in external platform and basin was synchronous with: a) Active tectonic diapirism sourced by mobilization of the deep Triassic salt, with diapiric extrusions reaching the seabed during the Early Cretaceous to Quaternary time interval; b) From Paleocene times the occurrence of marine volcanic flows sourced from Lanzarote and Fuerteventura and increasing their activity during the. Eocene and Pliocene times.