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The Cretaceous Cardium Formation, throughout 10,000 sq mi of the Alberta basin, is composed of almost contemporaneous, noncontiguous sandstone bodies which are present as far as 100 mi east of the maximum regression of fluvial and lagoonal lithofacies.
Individual bodies are separated by marine shale and consist of 1 or more linear bars, which abut abruptly against shale on the basinward flank. The sandstone is coarser and cleaner toward this flank, which is fringed by conglomerate in many places. The base of the sandstone is transitional with the underlying shale through a sequence that becomes coarser toward the top. These gross features of Cardium stratigraphy are unlike a normal cycle of shoreline regression.
Comparison is made with models based on 4 basic variables: vectors of sediment supply and dispersion, void space due to subsidence, and volume filled by sediment accumulation.
Models representing delta progradation and turbidity-current deposition are characterized by continuity of supply and dispersion and gradational relations between sandstones and basin shales. Models representing shoreline progradation have discontinuity between supply and dispersion resulting in abrupt basinward contacts, but require juxtaposition and diachroneity of continental, littoral, and basinal lithofacies. Reworking on transgression results in a regional disconformity of which there is no evidence in the Cardium.
A model representing vertical accretion (shoaling) on a shallow stable shelf with localized sand accumulation satisfies all critical observations.
Comparison with appropriate modern areas of sedimentation indicates that the post-Pleistocene rise of sea level has imposed limitations on uniformitarian analogies.
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