BIOFACIES OF THE PIPE CREEK SHALE (LOWER KELLWASSER EQUIVALENT, UPPER DEVONIAN), HORNELL, NEW YORK

The Frasnian-Famennian extinction (Late Devonian) consisted of two pulses, the Lower and Upper Kellwasser Events, which are associated with deposition under anoxic or dysoxic conditions in many parts of the world. Numerous authors have invoked anoxia/dysoxia as a major kill mechanism in these events. Here, we investigate the macrofauna of the Pipe Creek Shale (Lower Kellwasser equivalent) at a locality in Hornell, New York (BCP), for evidence of dysoxia-tolerant fossil taxa. At this locality, the Pipe Creek consists of dark to light gray silty shale interbedded with thin siltstones, representing an offshore depositional environment. The underlying and overlying strata were deposited in shallower water. The Pipe Creek fauna includes brachiopods (e.g., Ambocoelia, lingulids, leiorhynchids, productids), conulariids, bivalves, and at least one gastropod. Some poorly preserved fossils may represent ammonoids, and Bush et al. (2015) identified a conodont as well. Some of these taxa have been associated with dysoxic environments in previous studies of Devonian shales; however, some samples contain numerous species and likely reflect higher oxygen levels. These results are consistent with previous studies that documented fluctuating oxygen levels in Devonian shales of New York State (Boyer and colleagues). Further paleontological and geochemical study could further constrain oxygen levels during the deposition of this unit.