Late triassic - jurassic dinoflagellate biostratigraphy, Western Arctic Canada
Abstract
Upper Triassic-Jurassic sedimentary rocks, consisting dominantly of interbedded sands, sandstones and shales, are exposed on Borden, Brock, Mackenzie King, Melville, and Prince Patrick islands. In ascending order, they are the Schei Point, Borden Island, Savik, Wilkie Point, Ringnes, Deer Bay, and Mould Bay formations. A total of eight surface sections and over 300 palynological samples form the basis of this study. The dinoflagellates recovered are assignable to 31 genera and 69 species, of which 12 species and 1 subspecies are described as new. They are classified under Apical, Intercalary Precingular, Combination, and Unknown archeopyle groups. Eleven species of acritarchs are described. Twelve dinoflagellate assemblage zones are established, using macrofossils as biostratigraphic control . These zones , designated with corresponding letter zones are: 1) Rhaetogonyaulax arctica - Sverdrupiella usitata assemblage, TA Zone, Late Karnian; 2) He i bergella aculeata - Sverdrupiella septentrionalis assemblage, TB Zone, Norian; 3) TC Zone, Rhaetian - No data available; 4) Lithodinia canadensis - Sentusidiniwn psilatwn assemblage. JA Zone, Hettangian? - Late Sinemurian; 5) Ctenidodiniwn arcticum - Nannoceratopsis gracilis senex assemblage, JB Zone, Pliensbachian (?) - Late Toarcian; 6) Leptodinium arcylatum - Nanno ceratopsis gracilis gracilis assemblage, JC Zone, Bajocian; 7) Ctenidodiniwn orrrza,twn - Valensiella ampulla assemblage, JD-1 Zone, Early Bathonian; 8) Energlynia acollaris - Pareodinia evittii assemblage, JD-2 Zone, Late Bathonian; 9) Paragonyaulacysta calloviense - Pareodinia granulata assemblage, JE Zone, Callovian; 10) Gonyaulacysta jurassica jurassica - Hystrichogonyaulax cladophora assemblage, JF-1 Zone, Early Oxfordian; 11) Gonyaulacysta dualis - Horologinella spinosigibber osa assemblage, JF-2 Zone, Late Oxfordian to Early Kimmeridgian; and 12) Pareodinia capillosa - Tubotuberella apa t ela assemblage, JG Zone, Late Kimmeridgian to Portlandian. The ratio of dinoflagellates and acritarchs to pollen and spores was used to determine the relative distance from ancient shorelines. From this data, the paleoenvironments of each formation were classified into nearshore, middleshore, and offshore regimes. These interpretations were supported by sedimentological, foraminiferal and paleontological data. Correlation using stratigraphic, paleontological, and palynological techniques leads to the recognition of Triassic- Jurassic and Middle-Upper Jurassic unconformities in the western Sverdrup Basin.
Description
Bibliography: p. 214-231.
Keywords
Citation
Tan, J. T. (1979). Late triassic - jurassic dinoflagellate biostratigraphy, Western Arctic Canada (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/23346