Planetary and Terrestrial Structural Geology Research

The Research Program...

My research program incorporates the fields of structural geology, geomechanics, and tectonophysics, integrating field-based studies with lab-based numerical modeling analyses. I place strong emphasis on the use of analytical and numerical computation in order to better understand the mechanics of deformation in the Earth, and its applications to industry. My work thus spans the gamut between theoretical and applied.

My interests lie predominantly in the characterization of fracture and fault systems in three dimensions and the mechanics of fault failure as applied to earthquake behavior and fault evolution. My work necessitates detailed characterizations of the state of stress in actively deforming environments, facilitating the prediction of fault behavior and associated deformation, such as folding and fracture development.

I spend much of my time applying these techniques to the analysis of the geology of other planets and moons in the solar system. For example, I am working on NASA-funded projects investigating the development of faults and fractures in the ice crust of Jupiter's moon Europa, and Saturn's moons Enceladus and Titan, and fault and dike systems on Mars. I also have numerous field-based terrestrial projects, including in the East African Rift Valley, the Iceland spreading ridge, the Western Desert in Egypt, and normal faulting projects in California and Utah.

Field Locations

See descriptions of these potential research areas below.

Research Opportunities...

I am involved with several projects, all of which provide excellent potential for graduate student research topics, so be sure to contact me if you are interested!

Terrestrial Research

Controls on Continental Rifting in East Africa:

Continental breakup is the precursor to ultimate plate separation and seafloor spreading at midocean-ridge systems. However, the fundamental processes by which thick continental lithosphere is broken, thinned, and ultimately split apart are enigmatic. It is known that magma plays an important role during the transition to seafloor spreading; however, the role of magma early in the continental rifting process is unclear. Past work suggests that plate tectonic stresses alone are insufficient to account for the rifting of continental lithosphere, and that magma must therefore be an active player in the continental rifting process, as opposed to a passive response. We are examining the process of continental rifting in a youthful rift system (<5 Myr old) in order to determine the relative contributions of magmatic and tectonic processes. This work also examines the progressive evolution of fault systems as activity migrates away from the dominant border faults into the rift center with ongoing extension, as well as the evolution of magmatic centers, volumes, and strain through time. We focus on the Natron rift basin of northern Tanzania and the Magadi rift basin of southern Kenya. These basins are also important for understanding the evolution of modern hominids, as early rifting processes affected the environments in which early humans lived. Funding Agency: NSF (through 2014). Past Graduate Students: Matt Blakeslee. Current Graduate Students: James Muirhead. Collaborators: Cindy Ebinger (University of Rochester); Tobias Fischer (University of New Mexico). Most recent conference abstract: GSA 2013.

Plate Boundary Evolution in Iceland:

If you're interested in traveling to the furthest corners of the globe, why not consider fieldwork in the natural geologic laboratory of stunning Iceland? Where the North American and Eurasian plates are wrenching apart from each other, huge faults and fissures have ripped open the surface of Iceland, often associated with major earthquakes and basaltic volcanism. This is a dynamic and exciting place to learn about the fault evolutionary process at an obliquely-spreading plate boundary, and to unravel the link between plate motions, faulting, earthquakes, and volcanism. We have been collaborating with Amy Clifton, until recently at the Nordic Volcanological Center, University of Iceland, in an attempt to unravel the pattern of, and variability in, fault development on the Reykjanes Peninsula. Funding Agency: NSF (until 2006; no current funding). Past Graduate Students: Jim Grant; Leslie Fernandes; Nate Boersma; Jane Barnes. Collaborators: Amy Clifton (University of Iceland). Most recent conference abstract: GSA 2013.

Evolution of the Hat Creek Fault, California:

Although Northern California is not highly populated, earthquake risks do exist in the region due to a number of active normal faults in the region of Lassen Peak and Mt. Shasta. A major player in this regard is the Hat Creek fault system, just north of Lassen Peak. The Hat Creek fault shows clear evidence of a prolonged period of activity, manifested as up to 350-meter-high fault scarps in Tertiary basalt lava flows. More recently, these scarps were abandoned and active scarps developed in the hanging wall, cutting through <30,000-year-old basalts (the Hat Creek basalts). These scarps show evidence of having displaced <15,000-year-old glacial gravels by as much as 20 m. Nonetheless, the timing of the most recent earthquake along the fault and the potential for future earthquakes have not been evaluated. We are conducting detailed mapping of the vertical scarp geometry and associated monocline along the fault system to unravel the evolution of the fault system. In addition, we will be looking for evidence for Holocene earthquake activity using methods such as cosmogenic nuclide dating and lichenometry in the hopes of developing a future hazard assessment for the fault. Funding Agency:UI-Graduate Research Grants (through 2009). Past Graduate Students: Erin Walker; Nicole Bellino (undergrad); Matt Blakeslee. Most recent conference abstract: GSA 2012.

Formation of Upheaval Dome:

The creation of Upheaval Dome, Canyonlands National Park, Utah, has long confounded geologists. This giant circular hole in the Utah desert is actually a structural dome with an eroded central region caused by weaker, older rocks (possible salt) at the center of the dome. It has long been debated whether the dome represents the long-term effects of salt diapirism in the Paradox Basin or a meteorite impact scar. Recent work seems to support the meteorite impact hypothesis. Our work suggests that Upheaval Dome represents the end-result of a long history of deformation that was triggered by a meteorite impact but subsequently evolved as salt diapirism continued below the original impact site. We have undertaken detailed field mapping of structural features as well as thin-section petrographic work to unravel the mechanics of disparate deformation styles present in the rock units around the dome. Funding Agency: UI-Graduate Research Grant (2009-2010). Past Graduate Students: Rachel Daly. Most recent conference abstract: GSA 2010.

Polygonal faulting in the Western Desert, Egypt:

Polygonal faults are enigmatic in that multiple fault orientations are able to form contemporaneously, in contrast to Andersonian fault models. Such fault types have been described in producing oilfields and commonly exist below the sea floor, making them inaccessible. They have been interpreted to be the result of large scale mass wasting (underwater landslides); however, this process does not form homogeneous polygonal shapes, as is nonetheless commonly observed. A related phenomenon is orthorhombic faulting, in which faults represent a state of isotropic horizontal extension. The underlying causes of such strain fields is unclear. We have been studying a rare onland exposure of polygonal faults in the Western Desert of Egypt. These faults occur within Cretaceous chalks and are pervasively dilated and vein-filled, indicating the important role of high fluid pressures during faulting, presumably during burial and diagenesis. This ongoing work is part of a research consortium (Desert Eyes) coordinated through Hamilton College and Missouri University of Science and Technology, also involving the University of Idaho, University of Vermont, and Egyptian universities in Alexandria, Asyut, Damanhour, Sohag, and Aswan. Funding Agency: NSF (to Hamilton and Missouri S&T). Past Students: Eric Doubet (undergrad). Collaborators: Barbara Tewksbury (Hamilton College). Most recent conference abstract: GSA 2013.

Planetary Research

Fracture Development on Europa:

If it's something out of this world you're interested in, how about one of the moons of Jupiter? Europa has a relatively thin (<30 km) and intensely fractured crust of ice around an underlying ~100-km-thick ocean. What are the nature of the stress fields that produced these faults and fractures? What are their growth mechanisms? How similar are Europan faults to terrestrial faults? These questions are being addressed through detailed mapping of Galileo Mission images of the Europan surface, in order to characterize fractures and deformation sequences. Subsequent analytical models of stress fields related to effects such as tidal bulging induced by Jovian gravity may provide insights to the intense deformation history on Europa. Funding Agency: NASA (until 2011). Past Graduate Students: Sandi Billings; Scott Marshall; Justin Vetter; Julie Groenleer; Christina Coulter; Jonathan Kay. Collaborators: Louise Prockter (Applied Physics Lab). Most recent conference abstract: GSA 2013.
See 2008 article in Science Daily

Volcanoes, Faults, and Water on Mars:

There has been an increased amount of interest in Mars recently due to the discovery by recent rover missions of convincing evidence for the existence of surface water on the planet in the geologic past. The big question now is, what happened to all that water? Hydrogen signatures on Mars have been suggested to represent a proxy for subsurface moisture, particularly in the polar regions. However, we have discovered an interesting relationship between hydrogen signatures in the equatorial region of Mars and the local topography and fault patterns, suggesting that ancient faulted highlands may be controlling moisture distribution in some manner. Eruptive fissures from old volcanoes show evidence of lava flows from the fissures as well as megafloods into large drainage valleys, suggesting that magma interacted with subsurface ice. Funding Agency: NASA (through 2014). Past Students: Jon Meyer (undergrad). Current Graduate Students: June Clevy; Matthew Pendleton. Postdoctoral Researcher: Amanda Nahm. Collaborators: Devon Burr (University of Tennessee-Knoxville). Most recent conference abstract: GSA 2013.

Tectonics and Ocean Evidence on Enceladus:

NASA's current Cassini spacecraft mission to the Saturnian system is revealing a wealth of insight into the diversity and splendor of Saturn's major moons. I am particularly interested in the moon Enceladus. Similar to Europa, the surface of Enceladus is comprised of water ice that is pervasively fractured. Our recent work has revealed that Enceladus likely has a global subsurface ocean that drives much of the surface fracturing and the geyser-like eruption of plumes of water ice from the "Tiger Stripes" in the south polar region. Nonetheless, the pattern of fracturing is very spatially heterogeneous on Enceladus, which we are still trying to understand. We are addressing such questions through a detailed analysis of the fault and fracture patterns on the surface of Enceladus with the hope of unraveling the nature of the stress fields at the surface and hence perhaps the origin of these stresses. Funding Agency: NASA (until 2015). Current Students: Emily Martin; Marques Miller (undergrad). Past Students: Alex Patthoff. Postdoctoral Researcher: Amanda Nahm. Most recent conference abstract: GSA 2013.

Fracturing on Dione:

Dione is another enigmatic moon in the Saturn system. It is much bigger than Enceladus but it is unclear if it contains a liquid ocean beneath its ice shell. The surface is pervasively fractured; however, the fractures seem to arrange into localized rift zones. Some of the exposed fault surfaces are very bright, leading to the question of whether or not Dione may still be tectonically active. Another question is whether or not Dione may also be ejecting material into space, like Enceladus. With the addition of new data from the Cassini extended mission, and detailed mapping of fault patterns on the surface, we hope to illuminate some of the tectonic details of Dione's interesting surface. Funding Agency: NASA (until 2015). Current Graduate Students: Emily Martin. Postdoctoral Researcher: Amanda Nahm.

Tectonic Mountains on Titan:

Titan is the second-largest moon in the solar system (after Ganymede) and the largest in the Saturn system. Its thick nitrogen-rich atmosphere veils and icy surface composed of frozen methane and ethane, as well as evidence of liquid methane lakes, surface drainages, and equatorial sand dunes. Titan is also dotted with linear mountain belts that attest to the effects of tectonic processes that likely result in fault-induced uplifts. The type of faults involved and the causes of the deformation are unknown. We are examining the distribution of mountain on Titan in an attempt to determine the likely source of global stress responsible for the faulting, as well as considering the necessary stress magnitudes needed at depth in order to overcome the overburden and still be sufficient to produce frictional failure of the ice shell. We are also part of a team of scientists (headed by Dr. Jason Barnes of the University of Idaho) proposing a future mission to Titan (AVIATR) involving an airborne reconnaissance vehicle on Titan Funding Agency: NASA (until 2014). Collaborators: Jason Barnes (University of Idaho, Physics); Jani Radebaugh (Brigham Young University). Most recent conference abstract: GSA 2012.

Past Research Topics

Evolution of the Lake Mead Fault System:

The Lake Mead fault system in southern Nevada marks a region of strike-slip tectonics in a transitional environment along the margin of the Basin and Range extensional province. A complex interaction between the NE-SW striking Lake Mead fault system and the NW-SE striking Las Vegas shear zone has resulted in interesting growth patterns in the respective fault systems as they mechanically interacted and linked together. I am interested in unraveling the explicit fault patterns, concentrating on secondary deformation at the tips of strike-slip fault segments that ultimately facilitated linkages between mutually adjacent fault segments. Past Graduate Students: Scott Marshall. Collaborators: Scott Marshall (Appalachian State University) and Michele Cooke (University of Massachusetts-Amherst). Most recent conference abstract: AGU 2008.

Fracture Evolution in Basalt Lava Flows:

Have you ever wondered why basalt rocks that formed from lava flows have the fracture patterns inside them that they do? This is a problem that geologists have been studying for over 300 years, and we're still learning more about the interesting process of lava cooling to form fractured basalts. I am interested in the variability of fracture styles in lava flows with different thicknesses and different shapes. What is the importance of inflationary processes during lava cooling? How does inundation of the flow top by water impact on the cooling history? What can our understanding of the fracture process tell us about the permeability of fractured basalts, and how might this be important for groundwater flow or the migration of contaminants into the subsurface? Funding Agency: DOE/INEEL (ended 2002). Past Graduate Students: Conrad Schaefer. Most recent conference abstract: AGU 2003.

Sill Intrusion in Antarctica:

In perhaps the most unspoiled expanse of land on the planet, the Dry Valleys of Antarctica, 15 millions years of wind erosion in an unglaciated system of valleys has preserved some of the best exposures of igneous sills on Earth. These massive bodies of dolerite, exceeding 300 m thick, were intruded as enormous pools of magma, several kilometers below the surface of mid-Jurassic Earth, at the time of the initial stages of breakup of the supercontinent, Gondwana. The geometries that the sills make in the exposed valley walls provide important clues to the workings of the plumbing system of a major magma body. Rarely are we afforded such incredible insights into how a magma system develops at these depths in the crust. I am interested in using the specific geometries and patterns of sills to make inferences about the intrusion mechanics, including the possible magma flow directions in the subsurface. I have made one visit to the Dry Valleys and am hoping to revisit this amazing location in the coming years. Funding Agency: NSF (2005 workshop organized through Johns Hopkins University). Most recent conference abstract: AGU 2005.

Job Prospects...

So how is this stuff useful to a graduating student in search of a job?

A background in geomechanical studies provides students with the knowledge and skills necessary to embark on a variety of career paths. Here are a few examples:

Petroleum Industry: the structural characterization of an oil reservoir requires a comprehensive background in fault and fracture analysis, especially for making intelligent interpretations from 3D seismic data. Quantitative structural geology and geomechanics studies can make you a good candidate for a career in this field. Despite the vicissitudes of the petroleum industry, job prospects are usually good.

Geotechnical Engineering: the good thing about geotechnical consulting companies is that they are just about everywhere. A background in geomechanical studies can make you an appealing candidate for a job in this field. Such companies may be involved in a broad range of projects, including engineering site evaluations, structural geologic characterization, seismic hazard analyses, hydrogeologic investigations, environmental engineering, contaminant disposal or remediation, and mathematical and computer modeling. Fault and fracture studies have relevance to all of these fields.

Government Agencies: a background in fault mechanics and structural modeling can open doors for careers in government agencies concerned with fracture and fault issues, such as the U.S. Geological Survey, local state geological surveys, the Department of Energy, and NASA. Government research laboratories provide opportunities for postdoctoral research positions.

Academia: whether it be continued graduate studies or a teaching and/or research career in academia, studies in geomechanics provide a good foundation for an academic career in the spectrum of fields in structural geology.

Mining: many economic mineral deposits are either structurally deformed or are hosted in fractured rock. Accurate characterization of complexly faulted and fractured mineral fields requires a comprehensive training in both structural mapping and theoretical fracture mechanics. This expertise can be gained through research and instruction in the geomechanics program.

Environmental Geology and Hydrogeology: the activities of mankind have resulted in the release of numerous contaminants into the subsurface. These contaminants are often stored in fractures in the vadose zone, or move into the groundwater system, which is commonly hosted by fractured rocks. A knowledge of fracture development and characteristics in rocks is therefore useful to students interested in careers in contaminant remediation or groundwater resources management.