Publication Date


Document Type


Committee Members

David Dominic (Committee Member), Ernest Hauser (Committee Chair), Doyle Watts (Committee Member)

Degree Name

Master of Science (MS)


This study analyzes ten 2D seismic lines donated by CountryMark together with potential field data to examine the upper crustal structure near Wabash, Indiana. These seismic profiles reveal significant relief of the Precambrian Unconformity and prominent upper crustal reflections. The Precambrian Unconformity interpreted from the unmigrated stacked seismic sections is characterized by undulations and bowtie artifacts. Zero offset seismic models constructed using profiles of the exposed Precambrian Unconformity across the Eastern Granite-Rhyolite Province outcrops of the St. Francois Mountains feature the same seismic expression. The upper crust below the Precambrian Unconformity on the Countrymark seismic sections is also characterized by discontinuous high-amplitude reflections that occur ~0.5s two-way time below the Precambrian Unconformity. The distribution of these upper crustal reflections on a time structure map correlates with positive magnetic and gravity anomalies suggesting the reflectors are likely mafic. These geophysical observations are consistent with a scenario like that interpreted for the evolution of the Precambrian rocks of the St. Francois Mountains and also the findings of McBride et al. (2016) for patterns of reflections on seismic lines in central Illinois.

Page Count


Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded