TECTONIC AND EUSTATIC CONTROL ON ALBIAN SHALLOWING (VIKING AND PADDY FORMATIONS) IN THE WESTERN CANADA FORELAND BASIN

Late Albian shallowing in the Viking and Paddy Formations is investiga ted using a dynamic forward model on two cross sections through the We stern Canada Foreland Basin. The model incorporates flexural loading o f the evolving Cordilleran fold-and-thrust belt, sea-level changes, cr atonic tilt, and in-plane stress fluctuations. The stratigraphic obser vations are explained either by a rapid eustatic sealevel drop or by e astward tilting of the North American craton during late Albian times. In both cases, southward increases in the vertical growth rates of th e adjacent accretionary wedge are implied. Differences between the pre dicted stratigraphic patterns in the upper Albian formations of the we stern and southern parts of the Western Canada Foreland Basin demonstr ate the complications arising from local tectonics id determining eust atic sea-level fluctuations from sequence stratigraphy. The models als o show that changes both in the magnitudes of intraplate stress and in continental tilt forces can produce intrabasinal highs like those und erlying the upper Albian formations in the basin. Furthermore, sedimen t loading is demonstrated to affect the stratigraphic patterns in rela tion to the sedimentation rate and the rate of change of accumulation space.