Biotic response to a Middle Ordovician paleoceanographic event in eastern North America

Abstract

Global paleontological events such as mass extinctions have been the focus of attention in recent years, yet regional biotic events account for a greater proportion of extinction in the fossil record and should receive greater attention if we are to fully understand extinction processes over the Phanerozoic. We use a sequence stratigraphic framework to document a major extinction and migration episode that occurred in the Middle and Late Ordovician of North America. This event is characterized in eastern North America by coordinated changes in faunal assemblages, carbonate lithologies, siliciclastic influx, and phosphatization. We ascribe these changes to a regional paleoceanographic event brought on by thrust-driven flexural subsidence and sea-level fluctuations that lowered water temperature and increased turbidity and nutrient input.