Formation of coarsely crystalline, hydrothermal dolomite reservoirs in the Presqu'ile barrier, western Canada sedimentary basin
- McGill Univ., Montreal, Quebec (Canada) Geological Survey of Canada, Alberta (Canada)
- McGill Univ., Montreal, Quebec (Canada)
Late-stage, coarsely crystalline replacement dolomite and associated saddle dolomite cement from a widespread diagenetic facies in the Middle Devonian Presqu'ile barrier that extends southwestward from Pine Point to the subsurface of the Foothills in northeastern British Columbia. These dolomites create hydrocarbon reservoirs in otherwise tight limestones in the subsurface of the Northwest Territories and northeastern British Columbia, and host Mississippi Valley-type deposits at Pine Point. The coarsely crystalline replacement dolomite and saddle dolomite cement are interpreted to have formed during burial because they replace blocky sparry calcite cements, occur continuously across the sub-Watt Mountain unconformity, postdate stylolites and earlier replacement dolomites, and overlap sulfide mineralization. The [delta][sup 18]O values of both replacement and saddle dolomites increase eastward updip along the Presqu'ile barrier from - 16T PDB in the deeper subsurface of northeastern British Columbia to -7% PDB at Pine Point, whereas the corresponding homogenization temperatures of saddle dolomite fluid inclusions decrease from 178 to 92[degrees]C. The [sup 87]Sr/[sup 86]Sr ratios of coarsely crystalline and saddle dolomites decrease eastward along the Presqu'ile barrier from about 0.7106 in the subsurface of northeastern British Columbia of 0.7081 at Pine Point. These geochemical trends suggest a possible basin-scale migration of hot, radiogenic dolomitizing fluids updip eastward along the Presqu'ile barrier. Such large-scale fluid movements probably were related to Western Canada sedimentary basin tectonic compression and sedimentary loading, which occurred at least twice: during early burial between the Late Devonian and Early Carboniferous and during deep burial between the Late Jurassic and early Tertiary.
- OSTI ID:
- 6965959
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 78:1; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
BRITISH COLUMBIA
CANADA
CARBONATE MINERALS
DEVELOPED COUNTRIES
DOLOMITE
FLUID FLOW
FLUIDS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
HYDROCARBONS
JURASSIC PERIOD
MESOZOIC ERA
MIGRATION
MINERALIZATION
MINERALS
NORTH AMERICA
NORTHWEST TERRITORIES
ORGANIC COMPOUNDS
ORIGIN
RESERVOIR FLUIDS
RESERVOIR ROCK
SEDIMENTARY BASINS