ADDING CHEMOSTRATIGRAPHY TO A TRADITIONAL UNDERGRADUATE, LITHOSTRATIGRAPHIC FIELD PROJECT

Geosciences students at Colorado Mesa University learn traditional methods of measuring sections and correlation during coursework and field camp. We introduce an example of how a simple chemostratigraphic analysis is used to train students in geochemical field techniques.

The base of the Tidwell Member of the Jurassic Morrison Formation is defined by the lower contact of the informal “A” bed, which can be correlated in outcrop from western Colorado into eastern Utah. This study reports chondrite-normalized rare-earth elements (REE) concentrations from bentonitic clay layers in and near the “A” bed at multiple locales in Colorado and Utah. The geochemical ‘fingerprints’ of the bentonite layers reinforce stratigraphic correlation over broad distances.

Chemostratigraphy has evolved into an important tool in subsurface exploration, reservoir characterization, and well development strategies. Geochemical analysis of layers within a sedimentary sequence allows recognition of similar-to-identical chemical ‘fingerprints’ that can be useful for correlation, whereas contrasting geochemical signatures can help in the recognition of major geochronological boundaries, i. e., unconformities. Students who learn how to use chemostratigraphy to correlate stratigraphic sections in an actual field project are ready to apply chemostratigraphy in subsurface studies in industry and academia.