Abstract
Black Bear Ridge on Williston Lake is one of several important North American reference sections for intercalibrating the ranges of Upper Triassic ammonoids, conodonts, bivalves, ichthyoliths, and brachiopods. The section (Ludington and Pardonet formations) spans the uppermost Carnian through Hettangian of the Lower Jurassic. The co-occurrence of several fossil groups facilitates an integrated biozonation of the interval. Fossil fauna and biofacies serve to identify significant biological and sedimentary events in the history of the Late Triassic. Conodont and ichthyolith faunal change is gradual through the Carnian-Norian boundary, whereas conodont and ammonoid changes are dramatic across the Lower-Middle Norian boundary. Major transgressions are recog- nized in both the Lower and Middle Norian, and are marked by a conodont (Norigondolella) and ichthyolith (Birgeria) biofacies.
Published Version
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