HIGH RESOLUTION PALYNOLOGICAL ANALYSIS OF EOCENE LAMINATED SEDIMENTS FROM THE HORSEFLY LOCALITY, OKANAGAN HIGHLANDS, BRITISH COLUMBIA

We recently analysed palynofloras from five sites of the middle Early to early Middle Eocene Okanagan Highlands (southern British Columbia, Canada and northern Washington State, USA) to reconstruct vegetation across this broad upland Eocene landscape. Localities examined include Republic, Princeton, Hat Creek, McAbee, Falkland, Horsefly and Driftwood Canyon. All of these are today at more than 800m elevation, and are thought to have been at a similar elevation when the sediments were deposited. Initial counts of spores and pollen suggested that the region during the middle Early to early Middle Eocene was dominated by a mixture of Fir-Spruce (Abies-Picea) and Birch-Golden Larch (Betula-Pseudolarix) plant associations, with a diverse assemblage of other gymnosperms and dicots also present. One site, Horsefly, was considered for further research due to the potential to provide a high-resolution evaluation of Eocene environments for the Okanagan Highlands. The Early Eocene shales of the Horsefly site consist of alternating dark- and light-coloured laminae couplets, thought to represent winter and summer deposition (i.e., seasonal resolution). Numerous prior studies of fossil fish populations in these annual varves have yielded insight into the ecology of the Horsefly Eocene lake and suggested that intra-annual to millennial scale patterns could be resolved. This paper discusses the initial results of this high-resolution palynological analysis of these Early Eocene laminated sediments and investigates whether the Eocene vegetation of the Okanagan Highlands was responding to Milankovitch cyclicity, as has been shown for the Eocene Green River Formation.