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TitreSurface and subsurface signatures of gas seepage in the St. Lawrence Estuary (Canada): Significance to hydrocarbon exploration
AuteurPinet, N; Duchesne, M; Lavoie, D; Bolduc, A; Long, B
SourceMarine and Petroleum Geology vol. 25, no. 3, 2008 p. 271-288,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20060363
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC22B/13; 22B/14; 22C/03; 22C/04; 22C/06; 22C/07; 22C/09; 22C/10; 22C/11; 22C/15; 22C/16; 22F/01; 22G/01; 22G/02; 22G/03; 22G/04; 22G/05; 22G/06; 22G/07; 22G/08; 22G/10; 22G/11; 22G/15
Lat/Long OENS -70.0000 -66.0000 50.0000 48.0000
Sujetsbathymétrie; topographie du fond océanique; topographie du fond océanique; chenaux; gîtes en forme de traînée; caractéristiques sous-marines; transport sous-marin; profils sismiques; profils sismiques marins; capacité de production d'hydrocarbures; hydrocarbures; géologie du substratum rocheux; roches mères; reservoirs; trous; maturation; production d'hydrocarbure; Platform du Saint Laurent; combustibles fossiles; géologie marine; Paléozoïque; Quaternaire; Cénozoïque
Illustrationssketch maps; stratigraphic sections; seismic profiles
ProgrammeSécurité de l'approvisionnement énergétique du Canada
Résumé(disponible en anglais seulement)
The seabed of the St. Lawrence Estuary is characterized by many fluid releasing features. On multibeam bathymetric images these features correspond to crater-like depression (pockmarks) predominantly found on the northwestern shoulder of the ~300 m deep Laurentian Channel, as well as on the channel floor. Aligned pockmarks, which define segments up to 12 km long, are frequent in the Laurentian Channel, whereas they are preferentially associated with submarine landslides on the northwestern shoulder of the channel. On high-resolution seismic profiles, pockmarks found in the Laurentian Channel are characterized by seismic chimneys that may be traced down to the autochthonous Paleozoic rocks (St. Lawrence platform), suggesting a thermogenic origin for the gas. On the northwest shoulder of the Laurentian Channel, the seismic signature of pockmarks does not extend downward to the reflector that corresponds to bedrock (St. Lawrence platform and/or Grenvillian province) suggesting, together with high sedimentation rate, a biogenic origin for the gas. These results are discussed in the light of the data collected in the onshore parts of the St. Lawrence platform and suggest the presence of a mature hydrocarbon source. The conclusions are supportive arguments for the hydrocarbon prospectivity of both the onshore and offshore segments of the Paleozoic autochthonous domain (St. Lawrence platform).