CHAPTER 9: STRATIGRAPHY OF THE FRASNIAN-FAMENNIAN BOUNDARY INTERVAL IN SHALLOW-MARINE PALEOENVIRONMENTS OF NEW YORK AND NORTH-CENTRAL PENNSYLVANIA (WISCOY-CANEADEA FORMATIONS, UPPER DEVONIAN)

The Frasnian-Famennian mass extinction was one of the largest of the Phanerozoic, resulting in widespread ecological changes in marine ecosystems. It consisted of two pulses, the Lower and Upper Kellwasser events. There is considerable potential for studying these events in the Appalachian Basin. However, correlation of the Frasnian-Famennian boundary interval has been challenging in shallow-marine paleoenvironments because conodonts are relatively rare and facies can change significantly among localities. Brachiopods are abundant, however, and are useful for regional correlations of shallow-marine strata, while carbon isotopes are useful for correlations with offshore sections and other geographic regions. With these tools, we correlate the dark shale above the Wiscoy Formation with the Pipe Creek Formation (Lower Kellwasser equivalent) and the dark shale above the Canaseraga Formation with the Dunkirk Formation. The Point Gratiot Bed (Upper Kellwasser equivalent) is recognized within the upper part of the Canaseraga Formation. We suggest dividing the Wiscoy and Canaseraga formations into members that will facilitate discussions of the extinction events.

About half the brachiopod species in New York and north-central Pennsylvania went extinct during the Lower Kellwasser event, with an approximately equal number of new species immigrating afterwards. Thus, the brachiopod faunas of the Wiscoy and Canaseraga formations are fairly distinct. However, only a couple species died out during the Upper Kellwasser event, and the pre- and post-extinction faunas are rather similar.