Lower Carboniferous Algal Microflora, Southwestern Alberta

Abstract

A diverse and relatively prolific Lower Carboniferous algal microflora has been encountered in the Rocky Mountains and Foothills of southwestern Alberta. The algae occur in the Banff, Livingstone, Pekisko, Shunda, Turner Valley, Mount Head, and lower Etherington Formations. They are generally conspicuous throughout the Banff Formation, scarce in the Livingstone Formation, but are rather abundant in the upper parts of the Pekisko and Shunda Formations, and in the Loomis, Opal, Marston, and Carnarvon Members of the Mount Head Formation.The most favorable facies for algae are mixed skeletal and oolitic-skeletal packstones—grain-stones representing shallow, open sea shoals. Lagoonal deposits also yield a very rich microflora. The most unfavorable facies are echinoderm-bryozoan packstones, and sandy, silty mudstones and wackestones found in relatively deeper, offshore lithofacies.Twenty genera and at least 22 species are recognized, of which 6 genera and 9 species are new taxa. The new forms are: Orthriosiphonoides salterensis, n. gen., n. sp., Intextulella agglomerata n. gen., n. sp., Pseudokamaena armstrongi n. gen., n. sp., P. boulderensis n. sp., Stacheoides ? spissa n. sp., S. tenuis n. sp., Epistacheoides nephroformis n. gen., n. sp., Pseudostacheoides loomisi n. gen., n. sp., and Asphaltina cordillerensis n. gen., n. sp.The present study indicates that the associated Foraminifera offer a better detailed zonation of the Lower Carboniferous than the algae, although the latter appear to be more sensitive to facies change and, therefore, may be more useful to reconstruct paleoenvironments. However, five local algal assemblages, based on the succession of genera, seem stratigraphically consistent in Alberta.