Building upon ichnological principles: modern biogenic structures, ichnotaxonomic classification, and paleoecological and stratigraphic significance of ichnofossil assemblages

• Author / Creator

  Dafoe, Lynn T.

• Biogenic structures can impart important information regarding animal behaviors and depositional conditions at the time of colonization including: sedimentation rate, current velocities, distribution of food resources, oxygenation, salinity, and temperature. This thesis utilizes various ichnological subdisciplines to build upon these underlying ichnological principles.

  Neoichnology is a newly emerging field that can provide invaluable information about modern and ancient organisms. Burrowing activities of a population of deposit-feeding, freshwater Limnodrilus and Tubifex is found to produce biogenic graded bedding. Similarly, the burrowing activities of Euzonus mucronata are studied in relation to the trace fossil Macaronichnus segregatis, which displays mineralogical segregation between the burrow infill and mantle. The process of grain partitioning was assessed using videographic analyses of ingested and excreted grains by these deposit-feeding polychaetes, which selectively ingest felsic grains through en-masse feeding in felsic-rich locales.

  Macaronichnus is an important trace in ancient deposits of nearshore settings; however, since its inception, the genus had not been formally diagnosed. Accordingly, a unique approach to classification of these traces was undertaken, using grain sorting and collective morphology as ichnotaxobases, in addition to the diagnosis of a new, related genus—Harenaparietis. In the Permian Snapper Point Formation of SE Australia, a new ichnospecies of Piscichnus was diagnosed and interpreted to reflect fish or cephalopod feeding via hydraulic jetting into the substrate in search of infaunal food sources.

  The delineation of trace fossils through ichnotaxonomy provides a basis for identifying trace fossil suites, which can be interpreted through ichnofacies analysis. Subtle ichnological and sedimentological attributes of deltaic strata in the Viking Formation permits the identification of wave-influenced and mixed river- and wave-influenced deposits in the Hamilton Lake and Wayne-Rosedale-Chain areas of Alberta, Canada, respectively. Facies analysis combined with the identification of palimpsest stratigraphic surfaces led to the identification of transgressively incised shoreface deposits at Hamilton Lake. Examples of palimpsest ichnofossils from the Hamilton Lake area and from other strata are used in an assessment of soft-, stiff- and firmground suites. This study revealed the importance of substrate properties, environment, stratigraphy and processes leading to the formation and expression of allocyclic and autocyclic surfaces.

• Subjects / Keywords

  • Palimpsest suite
  • Ichnotaxobase
  • Ichnotaxonomy
  • Euzonus mucronata
  • Stiffground
  • Harenaparietis
  • Ichnofacies analysis
  • Glossifungites Ichnofacies
  • Biogenic grading
  • Mineral segregation
  • Tubificid
  • Wave-influenced delta
  • Burrowing rate
  • Mixed river- and wave-influenced delta
  • Firmground
  • Piscichnus
  • Neoichnology
  • Hydraulic jetting
  • Viking Formation
  • Softground
  • Macaronichnus

• Graduation date

  Fall 2009

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3BQ06

• 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.