Chronostratigraphic Framework for Paleocene Palynozones, Western Canada

Time control is critical to appreciating the rate of floristic changes subsequent to the K-T boundary event. Using magnetostratigraphy and radiogenic ages it is possible to calibrate the Paleocene palynological zonation of Western Canada with international time standards. The 8 m.y. long Paleocene spans polarity chrons 29r (upper part) through to 24r (lower part). Using both composite outcrop sections (Calgary, Red Deer and Hinton areas) and cored boreholes located in both the Plains and Foothills regions of central Alberta, polarity subchrons have been established within a number of the chrons, which allows a more constrained time framework to be applied to the palynological zonation. These and radiogenic ages, allows the projection of lines of correlation across the axis of the Alberta syncline.

The palynological zonation for the Paleocene of Alberta includes the Wodehouseia fimbriata, Momipites wyomingensis, Momipites actinus, Aquilapollenites spinulosus, Caryapollenites wodehousei and Pistillipollenites mcgregorii zones and four subzones. The length of individual palynological zones has been determined to vary significantly with short periods of biostratigraphically recognizable change separated by long periods of relative stability. This reflects variations in the rate of change (phlyogenetic and immigrations?) within the floras. Three intervals of rapid change occur: immediately post K-T boundary; Early/Middle Paleocene transition; and Middle/Late Paleocene. For the latter two, the increased rate of change corresponds to basinal events. Times of maximum elevation in the orogen, maximum development of the foredeep, and emergence/erosion of the peripheral bulge correspond to rapid change. Slower subsidence, broader alluvial plains with transverse drainages are associated with times of stable floras.