ABSTRACT

The Upper Cretaceous (Turonian - Coniacian) Cardium Formation within the Kakwa region of west-central Alberta contains strata deposited in marine, marginal marine and terrestrial environments. These environments are represented in the Main sandstone (Ram Barrier) and the overlying C-unit (Ram Back Barrier) as an upward progression displaying the following nine facies: 1) bioturbated mudstones; 2) sharp-based centimetre to decimetre-scale, fining upward rhythmites with gutter casts; 3) low-angle, inclined cross-stratified sandstones; 4) trough cross-stratified, planar bedded and massive sandstones; 5) rooted sandstones; 6) massive, black, carbonaceous mudstones with oyster beds; 7) sharp-based, massive to ripple cross-stratified sandstones; 8) incipient paleosols; and 9) millimetre to centimetre, wavy to lenticular, interlaminated mudstones and sandstones with syneresis cracks and mudcracks.

In detail, the observed facies association may be fitted into a barrier island and back barrier/lagoon depositional system. Significant here is that over time, this depositional system may have been exposed to controls on accommodation that operated under two different states: 1) sea level low-stand, where barrier morphology is modulated by autocyclic processes dominated by progradation, inlet migration and or mining and excavation during storms; and 2) rapidly falling sea level, where barrier morphology is modified predominantly by excavation and deposition as sea level retreats.

End_of_Record - Last_Page 161-------