Abstract

The Ludlovian–Pridolian Cape Storm, Douro, and Somerset Island formations on eastern Prince of Wales Island form a transgressive–regressive succession that developed on the western flank of the active Boothia Horst. Sedimentation took place in a series of fault-bounded subbasins that were, at different times, characterized by abundant microbolites, rhodolites, brachiopods, and organisms that produced a diverse array of ichnofossils. Integration of paleoecological information from this succession provides a multifaceted paleoecological model, which can be applied to similar, lithologically monotonous successions throughout the world. Three main factors controlled the distribution of biota through the transgressive–regressive cycle. The most obvious factor was ever-changing depositional settings caused by progressive rise and fall in sea level. Superimposed on this general pattern, however, was the influence of water circulation and the influx of detrital quartz from the Boothia Horst. The microbolites and rhodolites were mutually exclusive; the microbolites developed in intertidal to shallow subtidal settings, whereas the rhodolites grew in subtidal settings. The exception is in the lower Somerset Island Formation, where oncolites and rhodolites are numerous, commonly in the same beds. The influx of detrital quartz grains into the intertidal and supratidal settings, common during the development of the lower part of the Cape Storm Formation and the upper part of the Somerset Island Formation, curtailed microbolite development. During the subtidal phase, circulation controlled the distribution of Atrypoidea-dominated brachiopod faunas, rhodolites, microbolites, and ichnofossils. Even subtle changes in the nature of the rhodolite associations were accompanied by changes in the Atrypoidea species and changes in the ichnofossil assemblages.

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