THE UPPER JURASSIC - LOWER CRETACEOUS IN THE RICHARDSON MOUNTAINS (NORTHWEST TERRITORIES, CANADA): PALYNOSTRATIGRAPHY AND PALYNOLOGICAL INSIGHTS ON THE TECTONO-STRATIGRAPHIC ARCHITECTURE OF THE CANADIAN ARCTIC MAINLAND

The Sverdrup Basin is a sedimentary basin underlying the Canadian Arctic Archipelago; it currently provides the primary reference framework for the tectono-stratigraphic architecture of the Canadian Arctic. It contains a nearly continuous record of the Mesozoic rifting events that led to the formation of the Arctic Ocean and the associated Amerasia Basin including a sub-Barremian unconformity. The Richardson Mountains, located in northwestern Canada, also contain a nearly continuous sedimentary record of Mesozoic events and are ideally positioned to investigate links between the tectono-stratigraphic evolution of the Sverdrup Basin and adjacent landmasses. Within the Richardson Mountains is a sub-Barremian unconformity, developed during a period of rifting and occurring erosionally at the base of the Mount Goodenough Formation. However, the precise age of the Mount Goodenough Formation, the unconformity, and its relation to polar tectonics remains uncertain.

The aims of this project were to temporally correlate the intra-Mount Goodenough Formation Barremian-aged unconformity in the Richardson Mountains region with the sub-Barremian unconformity in the Sverdrup Basin, and to provide new insight into (1) tectono-stratigraphic linkages with circum-Arctic areas and (2) the development of polar terrestrial ecosystems during a warm interval in Earth’s history. This was accomplished using quantitative palynology (the analysis of organic-walled microfossils including pollen, spores and algal cysts) to statistically correlate pollen and spore assemblages from the Richardson Mountains to those published from the Sverdrup Basin to test time equivalence and reconstruct paleoenvironmental conditions. Palynoassemblages of the Richardson Mountains, when compared to the Sverdrup Basin palynoassemblages, indicate that the Deer Bay Formation and Isachsen Formation are time equivalent to the Husky Formation and Mount Goodenough Formation respectively. Therefore, if the Mount Goodenough Formation and Isachsen Formation consist of time equivalent strata and contain similar palynoassemblages, the sub-Berriman unconformities present in the two formations may be coeval. Paleoenvironmental reconstruction shows that the environment was humid and alternated between warmer and cooler intervals.