GEOSCAN, résultats de la recherche


TitreHydrothermal dolomites in Hudson Bay platform: preliminary field and geochemical data
AuteurLavoie, D; Zhang, S; Pinet, N
SourceCommission géologique du Canada, Dossier public 7002, 2011, 22 pages, (Accès ouvert)
Documentdossier public
Mediaen ligne; numérique
ProvinceManitoba; Ontario; Région extracotière du nord; Nunavut
SNRC32L; 32M; 32N; 33D; 33E; 33L; 43B; 43G; 43H; 54K; 54L; 45; 46
Lat/Long OENS-96.0000 -68.0000 71.0000 50.0000
Sujetshydrocarbures; capacité de production d'hydrocarbures; bassins sédimentaires; roches sédimentaires; dolomies; dolomites; pétrographie; isotopes; études des isotopes stables; Plate-forme d'Hudson ; Bassin de Moose River ; Bassin de Foxe ; combustibles fossiles; Paléozoïque; Dévonien; Silurien; Ordovicien
Illustrationslocation maps; stratigraphic columns; photographs
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
ProgrammeBassins sédimentaires d'Hudson / Foxe Bay, GEM : La géocartographie de l'énergie et des minéraux
Diffusé2011 10 19
Résumé(disponible en anglais seulement)
Hydrothermal dolostone is one of the major producing hydrocarbon reservoirs in intracratonic basins in North America. The Hudson Platform is the largest intracratonic basin in North America but it is also the least explored. A first round of exploration took place from 1968-1985 period and resulted with the drilling of 5 dry wells in the central part of Hudson Bay and a few dry wells onshore Manitoba and Ontario. The first round of exploration occurred before the recognition of the economic significance of fault-controlled dolostone bodies. Fault-controlled porous dolostone and dolostone breccia, interpreted to be hydrothermal have been identified at two localities along the northern shore of Southampton Island (northern Hudson Bay). The dolostone breccia is partly cemented by saddle dolomite cement with up to 25% open pore space. In a well drilled near the town of Churchill in NE Manitoba, a 14 m interval of brecciated dolostone with dissolution porosity and partial infill by saddle dolomite cement was identified. In one part of this interval, dolomitization and silicification are physically associated to a vertical fracture that has been crosscut by the core. Oxygen and carbon stable isotope analyses of the dolomite cement yielded very negative ?18O ratios similar to those of coeval hydrothermal dolomite in other intracratonic basins. In the absence of microthermometric fluid inclusion data, the interpretation as being the result of precipitation from a high temperature fluid is still a working hypothesis. The delta13C ratios can be very negative, a situation commonly associated with the presence of biogenic-derived bicarbonate ions in the diagenetic fluid. The delta18O ratios of groundmass fabric-retentive dolomite have been acquired to compare with those of the saddle dolomite; the former yielded slightly more negative values than those of Upper Ordovician seawater and suggest that groundmass dolomitization likely proceeded from near marine fluid at slightly elevated temperature.