ABSTRACT

The Kicking Horse Belt is here recognized as a strip of country not over ten miles wide, at present recognized over a length of eighty miles, and occupying a single thrust-sheet in the Rocky Mountains Main Ranges, within which are localized many of the significant changes in Lower Paleozoic strata of southwestern Canada. These localized occurrences are as follows: 1) The only pronounced physical evidence for unconformity at the Lower Cambrian - Middle Cambrian boundary. 2) Westward pinch-out of the Mount Whyte Formation and of shale tongues in the Cathedral and Pika formations, all of Middle Cambrian age. 3) Westward facies change of the Middle Cambrian Stephen and lower Cathedral formations to deep-water facies. 4) Abrupt westward termination of the upper Cathedral Formation in a submarine depositional scarp. 5) Appearance of supratidal facies in abundance in the Middle Cambrian Cathedral and Eldon formations. 6) Westward appearance of slumped, slope facies in the Eldon Formation. 7) Eastward pinch-out of a tongue of outer-detrital facies within the Eldon Formation of the middle-carbonate facies. 8) Passage of the entire sequence of shelf carbonates of Middle Cambrian age into mudstones and argillaceous limestones of the lower and middle Chancellor Formation, to which a deep-water origin is ascribed. 9) Westward facies change of the clastic rocks of the Middle Cambrian Arctomys Formation to carbonates of the Waterfowl Formation.

Additional changes that may take place within the Kicking Horse Belt, but cannot be demonstrated to do so because of post-Laramide erosion, are the westward disappearance of the carbonates of the Upper Cambrian Mistaya and Middle Ordovician Owen Creek formations, and the westward change of the carbonates of the Lower and Middle Ordovician Outram and Skoki formations to graptolitic Glenogle Shale.

The Kicking Horse Belt encompasses the limits of temporal shifting of a slightly elevated paleotopographic feature, the Kicking Horse Rim. Throughout most of the time considered, the Rim prevented craton-derived fine clastic sediments (inner detrital facies) from reaching the deep-water basin. The Rim probably was localized initially in latest Early Cambrian time by a narrow tectonic welt. Once carbonate sedimentation was preferentially established on this linear "high," depositional processes and differential compaction may have sufficed to perpetuate the Rim, although tectonic renewal of relief cannot be ruled out.

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