The Use of Modern Burrowing Organisms to Determine the Paleoenvironmental and Paleoclimatic Significance of Continental Ichnofossils in the Eocene-Oligocene White River Formation, Northeastern Colorado, USA

Daniel Hembree
University of Kansas, Department of Geology
Lawrence, Kansas
[email protected]

Ichnofossils are invaluable to the interpretation of paleoenvironment, paleoecology, and paleoclimate. Understanding the information ichnofossils provide requires studying modern burrowing organisms and their traces. This project will test the hypothesis that variations in continental ichnofossil morphology are related to changing paleoenvironmental and paleoclimatic conditions by comparing ichnofossils to modern traces. These morphological variations will be correlated to: 1) such substrate conditions as soil texture, moisture, and organic content; 2) depositional environments; and 3) such climatic factors as temperature and precipitation.

Field studies will focus on the Eocene-Oligocene White River Formation in northeastern Colorado. The White River Formation consists of fluvial sandstone and conglomerate, floodplain mudstone and paleosols, and eolian siltstone. The field investigation will include the collection and description of ichnofossils, body fossils, sedimentological and paleopedological data, as well as the construction of stratigraphic sections for paleoenvironmental reconstructions. The morphology of the ichnofossils will be described quantitatively using five metrics including burrow depth, length, volume, diameter, and complexity.

The ichnofossils will be compared to invertebrate and vertebrate traces created in the laboratory. Experiments will be conducted in soil-filled aquaria with temperature and moisture levels set from the average, lowest, and highest tolerance levels of the test animals. Burrows will be cast and described with the ichnofossil metrics. Sediment mixing and ichnofabric models will be prepared using resin peels and x-radiography. A nonparametric analysis will test the prediction that the burrow metrics are related to environment. These data will be applied to White River ichnofossils to interpret paleoenvironmental and paleoclimatic conditions.

AAPG Search and Discovery Article #90033©2004 AAPG Foundation Grants-in-Aid