--> Abstract: Recognition of Paleovalley Systems and Associated Type I Unconformities within the Upper and Middle Mannville Subgroups of East-Central Alberta, by B. W. Mattison; #91012 (1992).
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ABSTRACT: Recognition of Paleovalley Systems and Associated Type I Previous HitUnconformitiesNext Hit within the Upper and Middle Mannville Subgroups of East-Central Alberta

MATTISON, BLAIR W., Mattison Geoconsulting, Calgary, Alberta, Canada

Seven stratigraphically separate valley-fill systems are found within the deposits of the Upper and Middle Mannville Group in the Cold Lake Oil Sands area of east-central Alberta. Type I Previous HitunconformitiesTop associated with the creation of incised valleys are traceable into regional shoreline systems, and on this basis, the Upper and Middle Mannville stratigraphic succession can be separated into seven distinct sequences.

Channel fill within paleovalleys is sand-dominant at most stratigraphic levels within the Upper and Middle Mannville Group and these deposits form excellent hydrocarbon reservoirs. Bitumen-saturated channel sands therefore form a significant component of the exploitable oil sands reserves within the Cold Lake deposit.

Depth of valley incision varies from sequence to sequence as well as paleogeographically. Difficulties in assessing the true depths of valleys and in separating single incision events from multiple events create uncertainty as to the extent of each separate channel incision event as well as the extent of relative sea level fall. Large variations in valley incision depth within closely neighboring sections indicate that multiple periods of tributary creation may have occurred during major incision events. Incision of some valley-fill systems may represent a complex response process in which multiple periods of incision and deposition followed a single fall in base level.

Inferred paleoflow directions within Middle Mannville paleochannel systems display a dominant west to east trend. Upper Mannville paleoflow trends maintain this west to east trend in the southern half of the study area while the dominant trend in the northern half is south to north.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)