J. F. Lerbekmo

The relationship between the iridium anomaly and palynological floral events at three Cretaceous-Tertiary boundary localities in western Canada

Profiles illustrating the abundance of iridium and the changes in the relative abundances of major groups within the palynoflora are given for three localities from western Canada. The peak abundance of iridium ranges from 1.35 to 5.60 ppb and corresponds to the base of a coal and to a floral-extinction event at the three localities. Immediately above the iridium-peak anomaly, angiosperm pollen is conspicuous in the assemblage, in contrast to the fern-spore spike described for sections in the mid-continental United States and at the Morgan Creek locality in south-central Saskatchewan.

Magnetostratigraphic and Palynostratigraphic Correlation of Late Campanian to Early Maastrichtian strata of the Bearpaw and Horseshoe Canyon formations between the CPOG Strathmore Corehole and the Red Deer Valley Section, Alberta, Canada

Abstract The Horseshoe Canyon and Bearpaw formations in the Canadian Pacific Oil and Gas Strathmore (CPOG) cored well (7-12-25-25W4M) in southern Alberta were sampled for magnetostratigraphy and palynostratigraphy. The studied interval begins in the continental upper Horseshoe Canyon Formation (early Maastrichtian) and continues to the base of the marine Bearpaw Shale (late Campanian) encompassing 358 m. A total of 152 horizons were sampled for magnetostratigraphy, and 48 horizons for palynostratigraphy. Four magnetozones (31r, 32n, 32r and 33n), 26 magnetosubzones and 8 cryptozones, a subdivision of a subzone, were identified. Most of the subzones had been previously identified in the Red Deer Valley outcrops. Magnetozone 32n in the CPOG core is only 70 per cent as thick as in the Red Deer Valley. Most of this difference occurs within the interval of coals 1 to 9 of the Red Deer Valley. The palynomorphs provide important information on the ranges of a number of key species that allow comparisons to other equivalent age sites in southern Alberta. These ranges indicate that the top of the CPOG Strathmore well is considerably younger than the top of Castor well as documented in Lerbekmo et al. (2003). The palynological results support the conclusions arrived at during the paleomagnetostratigraphic studies. The paleoecological inferences show similar oscillating marine and nonmarine conditions within the core developed by previous studies of the cored interval between the top of the Dinosaur Park and basal Horseshoe Canyon formations (Wall et al., 1971; Hills & Levinson, 1975).

Magnetostratigraphic and palynostratigraphic correlation of late Campanian strata of the Bearpaw and Horseshoe Canyon formations of the RCA Castor corehole to the Red Deer valley, Alberta

ABSTRACT The Research Council of Alberta stratigraphic corehole near Castor, Alberta (RCA Castor 13-34-37-13W4) was cored to a depth of 181.7 m (596 ft.) in 1967. The corehole was spudded in the basal Horseshoe Canyon Formation and continued into the top of the Dinosaur Park Formation. Fifty-six samples were studied for palynology and 44 stratigraphic levels were sampled for magnetostratigraphy. An additional 3 outcrop samples were taken for magnetostratigraphy near Castor to supplement an interval of no recovery in the core. The recovered palynomorphs and their relationship to the magnetostratigraphy support regional correlations developed previously for the Red Deer Valley to Cypress Hills area of southern Alberta. The close magnetostratigraphic correlation between the Castor core and Red Deer Valley sections has enabled the recognition of polarity subchrons 32n.5n to 33n.3n in the Castor core. A hiatus of some 0.3 m.y. occurs below the Horseshoe Canyon Formation in the Castor core. The base of the Horseshoe Canyon Formation is shown to be a little younger in the Castor area than in the Red Deer Valley (32n.6n vs. 32r.1r), suggesting progradation from the west rather than northwest. The Second Castor Sandstone correlates to the Dorothy Sandstone of the Red Deer Valley. End_Page 70-------------------------