Carbonate microfacies of the Windsor Group, Nova Scotia and New Brunswick

The carbonate microfacies of the Windsor Group (Carboniferous System) are described in Nova Scotia and New Brunswick, The microfauna and algal microflora which abound in these marine platform carbonates are divisible into the following four assemblage zones (from oldest to youngest): 1) Archaediscus krestovnikovi-Biseriammina? sp. - Endothyranopsis crassaEoendothyranopsis sp. - Koninckopora sp. 2) Archaediscus krestovnikovi-Biseriammina? sp. - Endothyranopsis crassaprimitive Neoarchaediscus s_p. 3) Biseriammina? sp. - Endothyranopsis crassa, abundant Neoarchaediscus incertus - Plano spirodis cus sp. 4) Asteroarchaediscus sp. - Asteroarchaediscus baschkiricusEndothyranopsis crassa-Endothyranopsis sphaerica-Neoarchaediscus sp. - Neoarchaediscus incertus-Planospirodiscus sp. These zones are recognizable in the Windsor type section as well as in the Antigonish, Port Hood, and Sydney regions; although there are some minor discrepancies between the ages indicated by the microfossils and the generally accepted megafaunal ages, the microfauna generally confirms the chronostratigraphic value of the brachiopod-coral assemblages within the Windsor "Basin". In addition, the microfauna can readily be related to the Tethian and Arctic zonal schemes, and suggests correlation of the Windsor Group with the late Visean-earliest Namurian of Western Europe (zone 15 to zone 17). Characterization of chronostratigraphic horizons by biostratigraphic means must always be coupled with paleoecological analysis, because forarninifers and incertae sedis are dependent on environment and in particular on salinity. Archaediscidae are practically restricted to open marine fades, Tetrataxidae flourish in peri- 11 reefoid11 environment and calcisphaerids thrive in back-reef lagoons. Biseriamminidae, Earlandiidae and Endothyridae are widespread in most carbonates and are present even in hypersaline starved intertidal flats. The Windsor microfauna shows obvious paleobiological affinities to the Arctic fauna, and less pronounced affinities to the Cordilleran, Midcontinent and Appalachian faunas. Similarities to the European Tethian realm are minimal, although the Windsor shares enough common elements with the classical Visean-Namurian fauna of Belgium and England to allow direct biostratigraphic correlations.