NEW ICHNOLOGICAL AND SEDIMENTOLOGICAL EVIDENCE FROM GLEN CANYON NATIONAL RECREATIONAL AREA, CAPITOL REEF AND ZION NATIONAL PARKS: A REGIONAL ICHNO-FACIES IN CONTINENTAL TO MARGINAL MARINE (PRINCIPALLY TIDALLY INFLUENCED FLUVIAL CHANNELS) AND MARINE (QUITE, OFF, SHORE) ENVIRONMENTS FROM THE LOWER TRIASSIC MOENKOPI FORMATION

By incorporating ichnological and sedimentological analysis with regional outcrop data from Glen Canyon National Recreational Area, Capitol Reef and Zion National Parks, of the Moenkopi Formation we seek to provide an introduction and overview from an ichnofacies perspective. Early Triassic exposures of these three National Parks in Utah, vertebrate, invertebrate, and plant ichnites in marginal marine, (principally, tide dominated fluvial systems) and quite-offshore marine settings are concentrated in lithofacies that are interpreted to have been deposited in continent to shoreline to off-shore environment’s. We have identified, with a high degree of certainty, the types of depositional environments represented by the rocks at various locations within these National Parks. Because the depositional environment of these rocks are well understood, information about the presence or absence of different types of trace fossils in different lithofacies can be used to identify specific trace fossils that are strongly correlated with the depositional environment.

In this study the consistent association of trace fossils of Chirotherium, Rhynchosauroides, Rotodactylus, and Undichna vertebrate ichnites, coupled with Kouphichnium, Rotamedusa, Palaeophycus, Fuersichnus and Arenicolites invertebrate ichnites, rare Equisetum(?) plant and body traces of horseshoe crab, shrimp-like crustacean’s, and fish with rocks deposited in shoreline and offshore environments, and the absence of these traces in rocks deposited in other environments, is interpreted to indicate that the presence of these types of ichnites can be used as an indicator of shoreline and offshore settings.

Future studies will determine whether or not this ichnocoenosis has the potential to delineate shoreline and offshore environments in rocks deposited elsewhere on other National Parks Land here in the Western U.S. Comparisons of Moenkopi outcrop at these National Parks provides us an opportunity for lateral and temporal stratigraphic correlations that will help us understand the oldest known Mesozoic flora and fauna relationships during the Early Triassic of North America.