Lithofacies Distribution and Continuity of Cardium Formation (Upper Cretaceous-Turonian) Tempestites, Alberta Foothills, Canada

F. F. Krause

Tempestite lithofacies associations recognized in previous studies of the Cardium Formation reservoir in the Pembina field have been identified and mapped in five outcrops in the Foothills of Alberta. Mesoscale and macroscale maps depicting the lateral continuity and distribution of this lithofacies association indicate that each lithofacies represents a lithosome. Significantly in the outcrops studied, the continuity of lithosome 4, whose flow capacity is an order of magnitude greater than that of other sandstone lithosomes in the Pembina field, decreases with increasing relative distance from shore.

Lithosomes in shore-proximal positions are often bounded by macroscale disconformities and are characterized by homogeneous and laterally continuous deposits of lithosomes 2 and 4. In shore-distal deposits, lithosomes 2 and 4 are intermixed and are typified by numerous diastems and disconformities of variable lateral extent. Meter-thick lithosome 4 intervals are segmented by discontinuous shale interlayers and continuous, decimeter-thick lithosome 2 intervals. In contrast, meter-thick lithosome 2 intervals are cut by numerous lenticular bodies of lithosome 4. Paleocurrent measurements indicate that these lenticular bodies are oriented northwest-southeast and that current transport was to the southeast. These data are important because they suggest that the northwest-southeast-oriented ridge-and-swale topography typical of Cardium Formation reservoirs is not simply an artifact of ravinement erosion and sedimentation during emplacement of overlying lithosome 4 conglomerates, but it is also a product of progressive emplacement and transport of underlying lithosome 4 sandstones. Thus, the ridge-and-swale topography is an inherited topography.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.