ICHNOLOGY OF THE UPPER DEVONIAN (FAMENNIAN) CATSKILL AND LOCK HAVEN FORMATIONS, CENTRAL PENNSYLVANIA: IMPLICATIONS FOR INTERPRETING PALEOENVIRONMENT AND PALEOSALINITY

Renewed interest in the Upper Devonian (Famennian) Catskill Formation (Fm) and its relation with the underlying and interfingering Lock Haven Fm has also sparked interest in the ichnology of these units. Our study-in-progress adds a new dimension to the understanding of the ichnodiversity and paleoenvironments in these fms that preserve the fin-to-limb transition. Localities being studied include Blossburg, Burlington, Canton, Dry Run, Covington, Lock Haven, Mill Creek, Ralston, Red Hill, Roaring Branch, Steam Valley, Tioga, and Trout Run.

A variety of lithofacies associations in the Catskill Fm reflects deposition in continental, transitional, and marine environments. Proximal and distal fluvial-alluvial deposits contain Beaconites, Camborygma, Kouphichnium, Lockeia, lungfish burrows, Naktodemasis, Paleohelcura, cf. Reniformichnus, scorpion burrows, Sagittichnus, Scoyenia, Steinichnus, and Undichna, as well as rhizoliths, rhizohaloes, and rhizocretions. Many of these deposits exhibit mostly weak pedogenic modification, though some exhibit moderate to strong pedogenesis. Transitional deposits contain Kouphichnium, Palaeophycus, Planolites, Skolithos, and Teichichnus. Catskill and Lock Haven strata deposited under increasingly marine to normal marine salinities contain traces in transitional deposit as well as Acanthorhaphe, Archaeonassa, Arenicolites, Asteriacites, Belorhaphe, Berguaeria, Chondrites, Conichnus, Cruziana, Curvolithes, Diplichnites, Diplocraterion, Gordia, Gyrolithes, Helicoichnus, Lingulichnus, Lockeia, Monocraterion, Monomorphichnus, Olivollites, Parahaentzchelania, Phycodes, Rhizocorallium, Rosselia, Rusophycus, Sagittichnus, Scolicia, Selenichnites, Thalassinoides, and Undichna. Archaeonassa, Palaeophycus, Planolites, and Protovirgularia occur in all environments in the studied areas.

Reconnaissance of Lock Haven Fm reveals lithofacies associations attributed to fluvial-deltaic deposition, including tidal modulation of sandy mouth-bar complexes. Trace-fossil assemblages are dominated by Teichichnus with occurrences of Planolites and Palaeophycus. Continued research will produce more trace-fossil assemblages from prodelta deposits and additional insight on spatial variations in shoreline paleoenvironments.