3D sedimentary evolution of a canyon fill (Lower Miocene-age) from the Mandorove Formation, offshore Gabon

摘要

Seismic and well data are integrated through 3D modelling and used to examine the sedimentary evolution of the Baliste-Crecerelle canyon, offshore Gabon. The canyon fill (4km wide, 400 m thick) forms part of the Mandarove Formation (Upper Oligocene-Middle Miocene age) and was fed by a major delta system of the Ogooue River. Salt diapirism influenced the position of the canyon and had a local impact on the filling. Two major fining-upwards stratigraphic cycles are recognised within the canyon. The deposits of sinuous gravity flow channels (100-300 m wide) which show a wide range of planform geometries dominate the canyon fill. The width, amplitude and wavelength of channels recognised within the two stratigraphic cycles are notably different. Canyon filling results from phases of erosional bypass and aggradational filling at the scale of a single turbidite channel story and at the scale of the canyon itself.