A palynological investigation of the till succession from the Weyburn oilfield, Weyburn, Saskatchewan, Canada

A palynological investigation of twenty-four samples from four boreholes drilled into the till on the Weyburn oilfield was undertaken. All samples produced abundant and well-preserved palynomorphs of Devonian, Carboniferous, Late Cretaceous and Quaternary age. The relative proportions of these elements proved relatively similar throughout; Late Cretaceous dinoflagellate cysts and pollen grains are the dominant elements, indicating that the principal sedimentary input to the till is from Upper Cretaceous (Campanian-Maastrichtian) units. Devonian, Carboniferous and Quaternary grains are consistently subordinate. The Devonian palynomorphs are from Manitoba to the north-east and the Late Cretaceous palynomorphs appear to be derived locally. The abundance of palynomorphs is testament to consistently high levels of sedimentary rock input to the till successions. The relative homogeneity of the kerogen and palynofloras from the till samples has not allowed the palynological differentiation of units A and B. The four samples from the supposed ‘bedrock clay’ yielded similar palynofloras. These samples have high organic productivities, the highest levels of Devonian input, no Carboniferous spores, the lowest Cretaceous abundances, relatively high levels of both Quaternary taxa and non-age diagnostic palynomorphs. Because the palynomorph associations are so heterogenous and similar to the overlying unequivocal till the ‘bedrock clay’ is probably glaciogenic in origin.