Ichnology

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Ichnology

• Trace Fossil Classification

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Factors Influencing Classification

• Historically classified in descriptive,
  perservational, taxonomic, and ethological terms
• Ethological most important
• 7 recognized categories
• Resting traces
• Locomotion
• Dwelling
• Grazing
• Feeding
• Farming
• Escape

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Ichnofacies

• Developed by Adolf Seilacher (1967)
• Parameters controlling distribution change with
  increased depth

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Non-Marine Ichnofacies

• Only recognized is Scoyenia
• Suggestive of shore zone of lakes and overbank
  deposits of rivers.

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Ichnofacies Marine

• Ichnofacies 1 Skolithos
• Many vertical (including U-shaped) burrows
• Clean, well-sorted sands, close to shore. Very
  shallow water, marine, high energy (wave,
  current action)
• Ichnofacies 2 Cruziania
• Cruziania Trilobite trace fossils trough-shaped
  (Paleozoic only)
• Thalassinoides isp. complex web, feeding and
  house burrows (maybe crabs, shrimps?)
• Marine shallow, lt 100 m low energy

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Ichnofacies Marine

• Ichnofacies 3Zoophycos
•  Broad, looping, helical, U-shaped traces low
  diversity
• Typical for lower oxygen conditions low energy
• Much organic matter in sediment
• Outer shelf/slope
• Ichnofacies 4Nereites
• Meandering/polygonal  traces at sediment surface
• low-food environment oxygenated
• Bathyal to abyssal (gt1000m deep) low energy

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Ichnofacies Marine

• Ichnofacies 5-7 Controlled by substrate
• Glossifungites firm, not rock
• Trypanites rock boring
• Teredolites wood borer (shipworm)
• Ichnofacies 8 Psilonichnus
• On land close to coast, above tide level (maybe
  crabs?)
• Vertical, Y-shaped
• Also in dunes in land (lakes)

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References

• Walker, R.G., James, N.P., 1992, Facies Models
  Response to Sea Level Change, 47-54pp.
  Metrolitho, Sherbrooke

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