ALL EXTINCTIONS ARE NOT CREATED EQUAL: COMPARISON OF FOUR EXTINCTION EVENTS THROUGH THE LATE DEVONIAN

The End Devonian extinction events combine to account for one of the most significant biotic crises in the history of life. Up to eight biotic turnovers or extinctions have been recognized from the Givetian through the Fammenian, supporting that this interval was likely a time of remarkable environmental stress. In order to better constrain the conditions surrounding these events and potential controls over extinction intensity, this study compares conditions from 4 different extinction events of varying magnitudes within the Appalachian Basin. This study takes a first look at bottom water redox conditions through, in stratigraphic order, the Rhinestreet, Lower and Upper Kellwasser, and Hangenberg extinction events. Samples were collected from western New York and eastern Ohio for trace fossil and trace metal signals. Interestingly, the Upper Kellwasser event at the Frasnian-Famennian transition, which is recognized as the most severe extinction event in terms of biodiversity loss, records comparatively the highest bottom water oxygen levels through trace fossil data, measured using ichnofabric index, and trace metal proxies (Mo, U, V, Ni, Mn). These results support that while oxygen stress was prevalent, and at some intervals anoxia and potentially euxinia were persistent, intervals with the highest oxygen stress were not associated with the greatest biodiversity loss.