Extension of lithofacies and conodont biofacies models of Late Devonian toEarly Carboniferous carbonate ramp and black shale systems, southern Canadian Rocky Mountains

Uppermost Devonian and Lower Mississippian strata in the Rocky Mountains of southwestern Canada and northwestern Montana record widespread oceanograph ic changes during middle to late Paleozoic time associated with the termina tion of a carbonate ramp system, the onset of a deep-water, low-oxygen even t and possible marginal tectonism, and the later reestablishment of a carbo nate ramp. Integrated lithofacies and conodont biofacies developed previous ly for these strata between the Bow Valley and the international border hav e been extended northward to the Athabasca region of the Alberta Rocky Moun tains. During early-middle Famennian time, the southern Canadian Rocky Moun tains region was the site of a westward-deepening and westward-thickening c arbonate ramp system (Palliser Formation). By late Famennian time carbonate ramp deposition ended and was followed by widespread deposition of organic -rich, low-oxygen facies in shelf to basinal environments (Exshaw Formation and correlative units). The overlying Banff Formation consists of anaerobi c to marginally aerobic, starved-basin to deep-ramp lithofacies succeeded b y shallower water carbonates; this sequence records basinward (westward) pr ogradation of the Banff ramp in middle to late Tournaisian time. Distinct c onodont biofacies representative of shallow-ramp to deep-basin settings tha t were previously recognized in the southernmost Canadian Rocky Mountains a nd Montana have also been identified to the north between the North Saskatc hewan and Athabasca valleys. Upper Palliser carbonates contain low-diversit y conodont faunas of indigenous to transported palmatolepid-, polygnathid-, and apatognathid-dominated assemblages. Exshaw deposits contain indigenous and reworked palmatolepid- and bispathodid-dominated assemblages and rewor ked or transported polygnathids. Lower Banff biofacies include transported and indigenous assemblages of siphonodellids, polygnathids, and pseudopolyg nathids representative of the deep-middle Banff ramp. Polygnathid-hindeodid biofacies of shallower middle-ramp environments occur higher in the Banff Formation in the North Saskatchewan and Athabasca valleys.