Santonian-early Maastrichtian radiolarian biostratigraphy of the northern mainland coast of Arctic Canada

Forty-six species of radiolarians recovered from the Upper Cretaceous Smoking Hills and Mason River formations in the Northwest Territories represent the first assemblage of this age from mainland Arctic Canada. Four interval zones and two subzones, calibrated to radiometric ages, are proposed based on the lowest and highest occurrence of index radiolarian species. These are 1) the Santonian/early Campanian Kuppelella aff. cayeuxi Zone, 2) the middle Campanian Diacanthocapsa aff. rotunda Zone (subdivided into the Kreuzstella vierkantiga and Lithostrobus borealis subzones), 3) the late Campanian Canadasphaera inuita Zone, and 4) the early Maastrichtian Stichomitra cf. communis-Xitus sp. B Zone. Integration of these radiolarian biozones with previously reported diatom, silicoflagellate, palynological and foraminiferal biozones and new radiometric ages indicate a middle Coniacianmiddle Campanian age for the Smoking Hills Formation and a middle Campanian-late Maastrichtian (probably Paleocene) age for the Mason River Formation. The radiolarian assemblages reported here resemble those of the North Slope of Alaska and western Siberia, allowing for biostratigraphic correlations within the Arctic Realm.