Paper No. 19-5
Presentation Time: 9:00 AM
FACIES ANALYSIS AND δ13CORG RECORDS ACROSS THE LOWER KELLWASSER EQUIVALENT (UPPER DEVONIAN) IN NEW YORK AND PENNSYLVANIA
The Lower Kellwasser event was one pulse of the Frasnian-Famennian mass extinction in the Late Devonian. In southern New York and northern Pennsylvania, the Pipe Creek Shale is equivalent to the Lower Kellwasser, as evidenced in part by a ~4‰ δ13Corg excursion. The Kellwasser equivalents are well known in deeper-water paleoenvironments preserved in western NY, but we are in the process of tracing them into shallow-water settings farther east. Shoreface facies are exposed at the bases of sections in Hornell, NY, Cameron, NY, and Tioga, PA (e.g., amalgamated, fine-grained sandstones with hummocky cross-stratification and/or swaley cross-stratification). The sections fine up through interbedded shales and tempestites to the fissile, dark gray shales of the Pipe Creek, interpreted as an offshore paleoenvironment. The Pipe Creek is directly overlain by an interval of sandy beds, informally referred to as the “Hammond Sandstone”. At Tioga, these sandy beds contain shale rip-up clasts and are overlain by pebbly sandstones bearing symmetrical ripples, which in turn are overlain by shalier strata. We interpret the “Hammond” to represent a forced regression that juxtaposed an offshore marine shale and a shoreface sandstone; it is capped by a transgressive lag. Subsequent facies variation is muted until the sandstones of the Canaseraga Formation. Even further onshore in Towanda, PA, the probable Pipe Creek is overlain by a thin interval of HCS/SCS that transitions into wave-rippled foreshore deposits. These results support other studies that have suggested relatively large sea level oscillations in the Lower Kellwasser interval, followed by more subdued variations in the interval between the Kellwasser events. The rapid facies variations correspond with the positive δ13Corg excursion, suggesting that disruptions to the carbon cycle could be related to sea level change at this time.