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TitreStratigraphy, sedimentology, and hydrocarbon reservoir potential of the Lower Cretaceous Jackass Mountain Group, Chilko Lake area, British Columbia
AuteurMacLaurin, K I; Mustard, P S; Mahoney, J B; Haggart, J W
Source 2008, 1 feuille
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20070536
RéunionBritish Columbia Geological Survey Branch, Interior Basins Workshop; Calgary, Alberta; CA; février 19, 2008
Documentdossier public
Mediaen ligne; numérique
SNRC92N/07; 92N/08; 92N/09; 92N/10
Lat/Long OENS-125.0000 -124.0000 51.7500 51.2500
Sujetsanalyses stratigraphiques; roches sédimentaires; Crétacé inférieur; sedimentation; milieu sédimentaire; sédiments marins; milieux marins; sédiments marins; caractéristiques structurales; faciès sédimentaires; structures sédimentaires; turbidites; hydrocarbures; capacité de production d'hydrocarbures; reservoirs; cadre tectonique; Groupe de Jackass Mountain ; Bassin de Methow-Tyaughton ; Groupe de Relay Mountain ; Formation de Nemaia ; Synclinal de Tsuniah Lake ; stratigraphie; sédimentologie; combustibles fossiles; tectonique; Mésozoïque; Crétacé
Illustrationslocation maps; stratigraphic sections; photographs; cross-sections
ProgrammeDendroctone du pin ponderosa, Réponse géoscientifique pour le dendroctone du pin ponderosa
Résumé(disponible en anglais seulement)
The Lower Cretaceous Jackass Mountain Group (JMG), near Chilko Lake in south-central British Columbia, is exposed southwest of the dextral Yalakom Fault and has been traditionally considered part of the Jura-Cretaceous Tyaughton Basin. The JMG in this area is over 2 km thick and unconformably overlies the Middle Jurassic Nemaia Formation and mid- to Upper Jurassic Relay Mountain Group. Preliminary data indicate an age range of Hauterivian to Albian. The rocks are exposed in a major east-northeast-trending synclinorium, which permits detailed examination of the lateral and vertical facies variations within the JMG. Detailed stratigraphic and sedimentologic analysis of JMG strata documents extensive shallow marine deposition, contrary to previous interpretations that described the bulk of the JMG as the deposits of deep submarine fan systems. In the northern limb of the syncline, over half of the strata are interpreted as shelf to shoreface deposits. These strata include extensive, moderately well-sorted sandstone bodies, decimetres thick, with common trough and hummocky cross-stratification, interpreted to represent high energy shoreface environments. Flaser and lenticular bedded facies also suggest that lower energy shoreface environments were widespread. These shallow marine strata are overlain by classic turbidite sequences, suggesting that in this area the basin evolved from shallow marine to outer shelf/slope environments over time. The JMG outcrops in the study area contain many similarities with exposed Cretaceous strata across the Yalakom Fault and 125 km to the southeast; the strata east of the fault dip northward beneath Tertiary basalts which cover subsurface Mesozoic stratigraphy. Assuming correlation with subsurface Lower Cretaceous Nechako Basin strata, the thick and extensive shoreface sandstones of the JMG in the Chilko Lake area provide a new subsurface hydrocarbon target with good reservoir potential, in addition to the previously identified submarine fan sandstone lithofacies. Ongoing geochronologic, geochemical, paleontological, and porosity/permeability analyses will help to constrain basin evolution and reservoir suitability.