Sinuous pockmark belt as indicator of a shallow buried turbiditic channel on the lower slope of the Congo basin, West African margin - Université de Montpellier Accéder directement au contenu
Article Dans Une Revue The Geological Society, London, Special Publications Année : 2003

Sinuous pockmark belt as indicator of a shallow buried turbiditic channel on the lower slope of the Congo basin, West African margin

Résumé

Pockmarks on the slope of the Lower Congo Basin are distributed along a meandering band on seafloor coincident with a shallow buried palaeochannel imaged from the 3D-seismic database. Each pockmark originates systematically at the channel-levee interface and the seafloor expression of the palaeochannel's sinuosity is mimicked by the sinuous trend of pockmarks. 3D-seismic on the slope, calibrated by biostratigraphic data from cores of the Leg ODP 175, indicate a seaward decrease of the sedimentation rate. We suggest that this condition induces a differential loading of the hemipelagic cover over the palaeochannel and propose a model for episodic dewater-ing of fluids trapped in the buried turbiditic channel. The consequence is a fluid flow caused by a longitudinal pressure gradient along the buried channel. A hydromechanical model proposed for the formation of shallow pockmarks indicates that the sedimentation rate cannot generate the overpres-sure required for pockmark formation on the seafloor. Therefore, it is suggested that hydrocarbon migration from deeper overpressured reservoirs is added to the pore fluid pressure in the shallow subsurface sediments. Horizontal drainage by the turbiditic palaeochannel and vertical migration along many vertical conduits (seismic chimneys) probably initiated at shallow subbottom depth. It is concluded that these shallow processes have important implications for fluid migration from deeply buried hydrocarbon reservoirs.
Fichier principal
Vignette du fichier
A1_2003_Geol_Soc_Spec_Pub_bis.pdf (6.55 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-01630677 , version 1 (22-03-2018)

Identifiants

Citer

Aurélien Gay, M Lopez, Pierre Cochonat, Nabil Sultan, Eric Cauiquil, et al.. Sinuous pockmark belt as indicator of a shallow buried turbiditic channel on the lower slope of the Congo basin, West African margin. The Geological Society, London, Special Publications, 2003, 216, pp.173-189. ⟨10.1144/GSL.SP.2003.216.01.12⟩. ⟨hal-01630677⟩

Collections

UNIV-MONTPELLIER
79 Consultations
229 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More