Paleoecological succession leading to a late Ordovician biostrome on Manitoulin Island, Ontario

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Abstract
A 4 m thick section in the Late Ordovician sequence on Manitoulin Island [Canada] revealed 4 successively shallowing carbonate environments, each with a distinctive fossil assemblage. The lowermost quieter water, muddy level bottom community was dominated by the brachiopod Zygospira. Next, increased laminar current action attracted smaller colonies of the tabulate corals Tetradium and Columnopora and locally small banks of corals and stromatoporoids were built up. In the protected shallow subtidal community following, encrusting algae (Girvanella) and upright match-stick Hedstroemia were more important, alongside Columnopora, cup corals and a diverse association of thick-shelled bivalves and gastropods. The short-term paleoecological succession terminated under turbulent conditions with large Labechia colonies, rugose coral colonies of Cyathophylloides and tabulate corals, e.g., Tetradium forming the Wekwemikong biostrome.