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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Proceedings of the Symposium on the Geology of the Canadian Arctic, 1973
Pages 241-257

Stratigraphic and Paleoenvironmental Significance of Upper Devonian Megaspores, Type Section of the Imperial Formation, Northwest Territories, Canada

B. I. Chi, L. V. Hills


The type section of the Imperial Formation was measured, described lithologically and sampled for palynological study. Three distinct megaspore assemblage zones: the Ocksisporites zone (lower); the Lagenicula devonica zone (middle); and the? Ancyrospora magnifica zone (upper) were identified. The Ocksisporites zone is characterized by the presence of Ocksisporites maclarenii, Ocksisporites spp., Nikitinsporites canadensis, Triangulatisporites rootsii and Lagenicula devonica. This zone grades upward into the L. devonica zone which is characterized by a marked increase in L. devonica and corresponding decrease in Nikitinsporites canadensis and Ocksisporites spp. The L. devonica zone changes abruptly upward into the? Ancyrospora magnifica zone which is characterized by? Ancyrospora magnifica and Lagenicula spp.

These zones can be correlated with identical assemblages described from upper Devonian strata on northeastern Banks Island and indicate that the basal beds of the Imperial Formation in the type section are Frasnian (but not lowermost Frasnian) in age whereas the? Ancyrospora magnifica zone is indicative of a low-mid Famennian age.

Fluctuations in megaspore abundance in 150 gram samples indicate cycles of marine transgression and regression.

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