A PALEOPEDOLOGICAL AND ICHNOLOGICAL ASSESSMENT OF LATE DEVONIAN PALEOENVIRONMENTS (CATSKILL FORMATION): PRELIMINARY RESULTS FROM CEDAR RUN, PENNSYLVANIA

A relatively complete 66 m stratigraphic section of the Catskill Formation along “The Narrows” in Cedar Run, PA was analyzed in order to assess temporal changes of Late Devonian paleoenvironments. This section is located approximately 30 km northeast of the well-documented Red Hill locality and is thought to occupy a similar stratigraphic interval since the section is along depositional strike and is approximately at the same level relative to the top of the Catskill Formation. At least five pedogenically modified horizons, several channel sandstones, abundant trace fossils (roots and burrows), and carbonized plant debris are present within this section. A transition from relatively thin (15-50 cm) Entisols and Inceptisols to a relatively thick (120 cm) Vertisol is observed in this section. Predominantly sub-horizontal clay-filled root traces (1-3 mm in diameter) are abundant in the lower portion of the section. This lower portion of the section also contains bedding-plane parallel, sinuous, bilobate trails (Undichna isp.; interpreted as drag marks from the fins of placoderm fish) and sub-horizontal, straight, smooth-walled tunnels approximately 20 mm in diameter (interpreted as arthropod burrows). The middle portion of the section contains vertically to sub-horizontally oriented clay-filled root traces ranging in diameter from 1-40 mm. This level also contains single vertical shafts up to 15 cm in diameter and ~20-40 cm in length (Hyperoeuthys teichonomos;interpreted as lungfish aestivation burrows). The top of the section contains thin drab-halo root traces (up to 12 cm in length). An increase in the abundance of lungfish aestivation burrows and vertic paleosols at the top of the measured interval suggests an increase in seasonality and the introduction of smectite-rich parent material. Since atmospheric O₂ levels are estimated to be below the threshold of forest-fire occurrence during the Frasnian, but elevated enough to result in abundant wildfires in the Famennian, carbonized plant debris from the section is currently being analyzed for the presence of charcoal to constrain the timing of deposition relative to the Late Devonian extinction event. Palynological analysis is also currently being conducted to further constrain the age of this section.