During the Late Mesozoic, the Western Canadian Sedimentary Basin evolved from a simple passive margin to a complex foreland basin. This thesis is an integrated outcrop and subsurface study of the stratigraphy, sedimentology, petrography and reservoir and source rock potential of the strata which record this transition in western Alberta.

The Early to Late Jurassic Fernie Formation is a thin, condensed sequence of marine shales, cherts, carbonates and highly quartzose (craton-derived) sandstones. The overlying Late Jurassic Cretaceous Kootenay and Nikanassin strata comprise a westward-thickening wedge of quartz and chert-rich (Cordilleran-derived) sandstones which are truncated by the pre-Cadomin unconformity. This unconformity records a major isostatic uplift of the orogen, and associated foreland basin. This uplift was probably initiated by collision-related crustal thickening and accentuated as the thrust sheet load was bevelled by erosion. The overlying Early Cretaceous Blairmore, Mannville and Luscar strata record another episode of basin subsidence resulting from additional thrusting in the foreland fold/thrust belt. The basal Cadomin, Gladstone, and equivalent Lower Ellerslie strata are Neocomian to Aptian in age. This interval contains quartz and chert-rich sandstones which were deposited by northwest-flowing river systems which traversed an aggrading alluvial plain. The Upper Ellerslie, Glauconite and equivalent Moosebar Formations are Aptian to Late Albian in age and comprise a northwestward-thickening wedge of brackish-marine mudstones and sandstones which were deposited during the episodic advance, and retreat, of the boreal Clearwater Sea into western Alberta. The overlying Beaver Mines and Gates Formations are Middle Albian in age. These strata record a major influx of coarse detritus into the basin from a volcanic source terrane in the southern Cordillera.

The chert and quartz-rich sandstones at the base and middle of the Blairmore-Mannville interval comprise good hydrocarbon reservoirs in western Alberta which typically retain fair-good primary porosity. The highly-quartzose Jurassic sandstones are typically tightly cemented with quartz overgrowths whereas the feldspathic sandstones in the upper part of the section are plugged with clay-carbonate cement. The Jurassic to Early Cretaceous shales are mature in the western Plains, overmature in the Foothills and are moderately rich in type II and type III organic matter.