Sequence Stratigraphy of Late Devonian (Frasnian) Carbonate Platforms from the Front Ranges of West Central Alberta

Six major third order sequences are recognized in the upper Devonian (Frasnian) carbonate strata exposed in the front ranges of west central Alberta. This stratigraphic framework is based on numerous measured outcrop locations tied to regional subsurface studies and conodont biostratigraphic data. The bounding surfaces and internal character of some of the sequences are described with examples from exposures located at Wapiabi Gap, Kiska, Cripple Creek and South Burnt Timber. Each sequence is initiated by a minimum sea level fall of greater than 10 m; as interpreted from onlapping stratal geometries and the abrupt juxtaposition of tidal flat/reef flat/reef margin-upper foreslope deposits over lower foreslope/basinal deposits.

A noteworthy aspect of these sequences is the common aggradational or even retrogradational deposition during sea-level highstands. In contrast, high rates of carbonate production and progradation characterize sea-level lowstands. This reflects the influence of environmental factors on stratigraphic stacking patterns.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California