Role of fluids in rock deformation - Fluids play an important role in the deformation of rocks. I am interested in how water and other fluids affect the behavior of quartz-rich rocks deformed at low temperatures. To characterize the nature of fluids and fluid pathways, I use a combination of field and laboratory studies, inlcuding transmitted light and cathodoluminescence microscopy, fluid inclusion microthermometry, stable isotope geochemistry, and FTIR. Specific targets have included fault zones and zones of anomalous crystal-plastic deformation. Geographically, these studies have been done in the Valley & Ridge and Piedmont provinces of the Appalachains, cratonic fault zones in the midcontinent, and the Silverton caldera of the southern San Juan Mountains of southwest Colorado.
Strain and deformation mechanisms in quartz arenites in foreland thrust belts - I am interested in how quartz arenites deform on a grain scale and how this relates to larger structures. I have worked on developing methods to partition the finite strain into strains associated with individual deformation mechanisms such as pressure solution and microfracturing. Much of my work has been on the Lower Silurian Tuscarora Sandstone and its correlative, the Massanutten Sandstone, in Pennsylvania, Maryland, West Virginia, and Virginia.
Recurrent tectonics in the craton - The craton is not the structural wasteland that many believe. It contains a number of major fault and fold zones that preserve a detailed record of long-lived deformation in a “stable” region of the craton. Two excellent examples of cratonic fault zones in the eastern midcontinent are the Bowling Green fault zone in northwest Ohio and the Kentucky River fault zone in northern Kentucky. Both were active for much of the Paleozoic and had profound effect on the stratigraphic development of the surrounding regions. In addition, they served alternately at barriers and conduits for fluid flow, including the widespread Late Paleozoic brine migration.
Paleoseismicity in the midcontinent - Silurian and Devonian carbonates in he craton of the eastern midcontinent contain abundant evidence of liquefaction, fluid escape, and soft sediment deformation. These features occur at numerous stratigraphic levels indicating that the cause was repetitive. The occurrence of these features is spatially related to known cratonic fault zones suggesting an origin by seismic shaking.
Shallow Geophysics - On the side, I also am interested in the application of shallow geophysical techniques to engineering and environmental problems. My students and I have used seismic refraction, magnetics, and resistivity to investigate slope stability problems, abandoned landfills, buried valleys, and fracture zones.