ABSTRACT

Bhattacharya (1988) divided the Dunvegan Formation in the subsurface into seven allomembers separated by regional marine flooding surfaces. His study area encompassed Townships 51 to 67 and Ranges 15 W5M to the edge of the deformed belt. This study is now being extended northward to encompass the Peace River Plains and Foothills, where Plint has measured more than 30 outcrop sections. Our aim is to integrate parasequences in outcrop with those documented in regional subsurface correlation lines, which currently extend 350 km from Beatton River (Twp. 86) to Berland River (Twp. 54). These lines show the Dunvegan to consist of a series of shingled, sandier-upward parasequences that downlap toward the southeast.

A section on the Muskeg River can be closely correlated with the subsurface, enabling the allomembers defined by Bhattacharya to be identified in outcrop. Facies and parasequence thickness trends, well defined in the subsurface, enable several closely spaced but nevertheless very different outcrop sections around Grande Cache to be correlated with some confidence. We correlate major incised fluvial units, up to 30 m thick in outcrop, with similar channels observed in allomember E in the subsurface. Paleocurrent directions in the channels and associated marine successions suggest a northeast-southwest to north-south paleoshoreline trend.

Many shoreface sandstones in outcrop are sharp based and suggest that shoreline progradation took place as a result of relative sea level fall. This supports the suggestion that progradation of the Dunvegan may have been driven, at least in part, by a major mid-Cenomanian eustatic fall at about 94 ma.

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