GEOSCAN, résultats de la recherche


TitreOrphan Basin, offshore northeast Newfoundland: unraveling the depositional history in a Frontier Basin
AuteurDafoe, L T; Keen, C E; Williams, G L; Dehler, S A
SourceAssociation géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 35, 2012 p. 32
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110339
RéunionGeological Association of Canada - Mineralogical Association of Canada Joint Annual Meeting; St. John's; CA; mai 27-29, 2012
Documentpublication en série
ProvinceRégion extracotière de l'est
Sujetshydrocarbures; capacité de production d'hydrocarbures; lithostratigraphie; combustibles fossiles; géologie marine; Cénozoïque; Tertiaire; Mésozoïque; Crétacé
ProgrammeGéoscience en mer, Analyse de bassin et ressources géoscientifiques
Résumé(disponible en anglais seulement)
Based on its proximity to the petroleum-rich Jeanne d'Arc Basin, the minimally explored Orphan Basin to the northeast is becoming an enticing area for oil companies focused on discovering oil and natural gas in offshore eastern Canada. Growing interest in Orphan Basin stems from an unusually attenuated continental crust, deep basin fill, and possible correlations to the lithostratigraphy of neighboring basins. In our study, we aim to unravel the depositional history of Orphan Basin and build linkages to the source-rock-bearing Jeanne d'Arc and Flemish Pass basins by integrating core and cuttings information with biostratigraphy, lithostratigraphy, and seismic interpretations. Our initial core analyses from the northern Jeanne d'Arc and Flemish Pass basins, denote a depositional change from restricted marine in the ?Middle to Late Jurassic to open marine beginning in the latest Jurassic and continuing through the Tertiary. During times of restricted marine deposition, 100s of metres of sediment accumulated in nearshore settings in the rapidly forming accommodation space. Conversely, open marine units encompass heavily bioturbated strata, reflecting continuous outer shelf to shoreface deposition. This prominent shift from restricted- to open-marine deposition can be attributed to rifting and subsequent drifting between the Grand Banks and Iberia, which opened the area to fully marine conditions as rifting of the North Atlantic propagated northwards. Well-log data from the neighboring basins suggests a similar environmental shift occurred, at least in part, within Orphan Basin. Log characteristics of the lower interval in the Great Barasway F-66 well (located in central Orphan Basin) may indicate a similar Late Jurassic restricted marine package, which we will attempt to confirm through palynological analyses.
One of the major discrepancies between Orphan Basin and Jeanne d'Arc Basin lithostratigraphy is the generally thin nature of Cretaceous and lower Tertiary packages bounded by unconformities. Lack of accommodation space at this time suggests that the basin did not undergo major subsidence to establish bathyal conditions until the middle Paleogene. Nonetheless, the thin Cretaceous packages such as progradational shoreface sands and distal shelf limestones are comparable to those of the Jeanne d'Arc Basin. However, thicker shoreface sandstones are generally confined to wells found in proximity to the Bonavista Platform (a prominent sediment source), whereas the central Orphan Basin is typified by shelfal shales. Our preliminary results above and our planned integrated studies should provide a more comprehensive understanding of the evolution and petroleum potential of Orphan Basin.