A New Lithostratigraphic Framework for the Cretaceous Colorado Group in the Cold Lake Heavy Oil Area,East-Central Alberta,Canada |
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| Authors: | Qiang Tu Claudia J Schröder-Adams Jim Craig |
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| Institution: | (1) Department of Earth Sciences, Carleton University, Ottawa, ON, Canada, K1S 5B6;(2) Jim Craig, Box 668, Bragg Creek, AL, Canada, T0L 0K0 |
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| Abstract: | The Albian to Santonian Colorado Group in the heavy oil area of Cold Lake, east-central Alberta represents a relatively condensed
section of shale-dominated sedimentation within the Western Interior Sea. These shales form the cap rock to the underlying
Clearwater and Grand Rapids formations that are exploited for bitumen extraction. Two cores covering the entire Colorado Group
provide a unique opportunity for establishment of a stratigraphic reference in an area that has received attention only for
its heavy oil-bearing Mannville Group. Based on sedimentology, geochemistry, micropaleontology, nannofossils, and wireline
log data, the Colorado Group was subdivided into the Joli Fou, Viking, Westgate, Fish Scales, Belle Fourche, Second White
Specks, and Niobrara formations. The Niobrara Formation was subdivided further into the Verger Member, informal Cold Lake
member, and First White Specks Member. Because of this region’s small accommodation space and distance to sources of coarse
clastic sediment, disconformities are indicated lithologically by bioclastic layers and missing biozones. Foraminiferal subzones
revealed two erosional boundaries associated with the Viking Formation. Faunal and floral evidence coupled with wireline log
correlations suggest that the Middle to Upper Turonian Carlile Formation, as described from southeastern Alberta, is missing.
That extends the Middle Turonian to Coniacian unconformity, as recognized in central Saskatchewan, westwards into Alberta. |
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| Keywords: | Stratigraphy Colorado Group Cretaceous western Canada shale |
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