Application of Ichnology Towards a Geological Understanding of the Ferron Sandstone in Central Utah

• Author / Creator

  King, Michael R

• Ichnology has long been used as a tool to aid in environmental interpretation, but has rarely been used as an ethological assessment tool in the Cretaceous Ferron Sandstone of central Utah. This study focuses on using trace fossils with detailed sedimentological analyses to describe continental, paralic, and shallow marine clastic lithologies from extensive outcrop and cores of the Ferron. In addition to applications for environmental interpretation, the toponomy and taxonomy of both vertebrate and invertebrate trace fossils are examined. The traces are examined in terms of assemblages, and important aspects such as palimpsest overprinting by deep-tiered burrowers and trace suites are discussed. Three new morphotypes of funnel-aperture trace fossils are described from the Ferron Sandstone representing two types of funnel-feeding behaviors. Most are representative of a head-to-tail circulation, however, one represents a tail-to-head circulation, with a branch interpreted to represent an inhalant tube. This study includes first descriptions of vertebrate taxa from the Ferron of Iguanodontipus, Amblydactylus, Chelonipus, and Characichnos. Additionally, morphotypes of small to medium theropods, and possible wading birds are identified. Identification of vertebrate traces during this time period (Turonian) is important due to the limited global preservation. The meniscate backfilled invertebrate trace Beaconites discussed herein is the first example of this trace from the Ferron. The rare occurrence of Rhizocorallium in continental settings is also described and discussed. This study of the Ferron Sandstone provides a rare insight into the interrelationship of continental and marine traces, as well as provides trace assemblages from both environmental examples in temporally related deposits. Most studies often focus on one environment or the other; the same applies to vertebrate and invertebrate taxonomy, for which the focus is often one or the other. In the Ferron Sandstone, continental traces may display more complex behaviors than typically reported. Channel sandstone contains traces ascribed to the plowing of molluscs, mayfly filter-feeding (Rhizocorallium), turtle movement (Chelonipus), and vertebrate swim tracks (Characichnos). Fluvial-lacustrine floodplains contain ornithopod tracks (Iguanodontipus and Amblydactylus), root traces, and often heavy burrowing of meniscate backfilled traces (Beaconites). Drier continental floodplains in contrast contain vertebrate tracks with roots and rare, small diameter Skolithos. In paralic environments such as tidal flats and shallow bays, a greater diversity of vertebrate tracks were preserved in assemblages containing marine-associated traces such as Thalassinoides and Ophiomorpha. Vertebrate trace fossils also occurred as large deformational structures along the tops of deltaic mouthbars: this is important to recognize since deformation in delta mouthbars is typically associated with the rapid loading of sediment. Tidal channels contained assemblages of Ophiomorpha, occasionally Siphonichnus, with interbedded mudstones with heavy bioturbation by Thalassinoides. Distal deltaic deposits have assemblages comparable to the proximal to archetypal expressions of the Cruziana Ichnofacies. The proximal deposits are more representative of the Skolithos Ichnofacies. When compared to other Cretaceous delta deposits, Palaeophycus is grossly underrepresented as a critical component of these assemblages. In the case, of Palaeophycus heberti, this may be the result of the trace fossils’ often cryptic appearance. Proximal deltaic deposits may show additional diversity in the form of deep-tiered overprinting taxa. The most commonly observed overprinting ichnotaxon was Ophiomorpha subtending down from the transgressive surface of erosion. The transgressive overprinting occurred mainly on proximal delta front or nearshore complex (washover fan) facies associations. The trace overprint of palimpsest deposits was very similar regardless of whether the overlying environment was a tidal channel, thin transgressive lag, or middle to upper shoreface. This is likely because the overlying environments were all shallow, with Ophiomorpha being a conspicuous deep tiered representative of these conditions.

• Subjects / Keywords

  • Turonian
  • Cretaceous
  • Sedimentology
  • Ichnology
  • Ferron Sandstone

• Graduation date

  Fall 2015

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39Z90M0S

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.