ABSTRACT

Lower Carboniferous rocks of the uppermost Banff Formation and the Rundle Group of southwestern Alberta contain an abundant foraminiferal microfauna and algal microflora, from which the distribution and relative abundance of 95 taxa have been determined. Foraminifera, which are most common in mixed skeletal and oolitic calcarenites, less common in micritic limestones, and least common in echinoderm-bryozoan limestones, permit recognition of Zones 7 to 16 of a widely applied zonal scheme derived initially from Carboniferous rocks of Europe. Vertical variations in foraminiferal families include an upward decrease in the abundance of endothyrids, tournayellids, and earlandiids, corresponding with an upward appearance and increase in the abundance of cornuspirids, forschiids, tetrataxids, palaeotextulariids, archaediscids, and others, and are similar to familial variations in Lower Carboniferous platform rocks in other parts of the world. The more precise correlations derived from the 95 microfaunal and microfloral taxa are in agreement with correlation of the Rundle Group, Pekisko, Shunda, and Turner Valley formations with the Rundle Group, Livingstone Formation, as recently indicated by lithostratigraphic and macrofaunal studies.

Preliminary foraminiferal zonation suggests the following ages: The uppermost Banff Formation is middle Tournaisian, whereas the overlying Pekisko Formation and the lower part of the Livingstone Formation are late middle Tournaisian. Foraminiferal data are as yet too meagre to delineate the precise Kinderhook-Osage boundary, in terms of the American Midcontinent stages. The Shunda Formation, and the middle part of the Livingstone Formation, are of late Tournaisian age. The Shunda - Turner Valley contact closely corresponds to the Tounaisian-Visean boundary, which is approximately equivalent to the Osage-Meramec boundary of the American Midcontninent Lower Carboniferous. The upper Livingstone Formation (type area only) and the Turner Valley Formation are of early Visean age. Overlying rocks of the Mount Head Formation (type area) are late early Visean to middle late Visean (Meramec). The Mount Head - Etherington contact corresponds to the base of the Aux Vases Sandstone (type Chester) of the Midcontinent. The transitional nature of the Mount Head - Etherington foraminiferal microfauna does not support the presence of a Meramec-Chester hiatus as previously postulated. The Lower Etherington Formation is latest Visean in age.

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