Structural and stratigraphic relations in the White River region, eastern Main Ranges, southern Canadian Rocky Mountains, British Columbia

The Front Ranges and Main Ranges in the Kananaskis area of the southern Canadian Rocky Mountains were profoundly influenced by Paleozoic tectonics. The Cambrian-Ordovician McKay Group is over 3000 meters thick and forms 4 outer-detrital-belt grand cycles. Two of these grand cycles have no counterpart in correlative rocks elsewhere in the southern Canadian Rockies and were preserved by Ordovician tectonics across an eastern embayment in a lower Paleozoic structural zone, the Kicking Horse Rim. Shale in the overlaying Glenogle Formation is replaced eastward by a shallow-water succession of quartzite and dolomite (the Tipperary Formation). The Middle Ordovician Skoki Formation disconformably overlies the Tipperary Formation and this disconformity is reflected in Glenogle shales by a missing graptolite zone and coarser clastics. 600 meters of strata are truncated by an angular uncomformity below the Upper Ordovician Beaverfoot Formation. The Beaverfoot Formation overlies Ordovician diatremes and at least one Ordovician normal fault. Middle Devonian strata angularly overlie a second set of diatremes.;Structures in the Main Ranges consist of tight, dominantly chevron-style folds, thrust faults that cut through the overturned limbs of folds, and normal faults that truncate earlier thrust faults. The intensity of spaced cleavage, indicative of significant pressure solution, changes within the stratigraphic column and is inversely proportional to fracture intensity. Deformation mechanisms are partitioned as a function of depth in the stratigraphic column and reflect inhomogeneous shortening within trust sheets. Structural continuity exists between the Main Ranges and Front Ranges subprovinces. The Bull River Thrust extends into the region from the south but dies out. The eastern Main Ranges represent a structural culmination in the Bourgeau Thrust sheet of the Front Ranges. Disharmonic folding between the Devonian and Ordovician sequences within the Bourgeau Thrust sheet is inferred from down-plunge projection. Inhomogeneous shortening within the Bourgeau thrust sheet allows for the up-dip conservation of fault displacement. The unusually thick Paleozoic sequence carried in the hanging wall of the Bourgeau Thrust cannot be balanced with any equivalent sequence in the footwall. The trajectory of the Bourgeau Thrust passed along the ancient Kicking Horse Rim and the thrust juxtaposes two unique Paleozoic sequences.