Graduate student Jeff Marsh maneuvering through a small channel near French River, Ontario

My research focuses on crustal rheology, or the mechanics of how rocks in Earth’s uppermost layer deform. Some of the overarching questions I pursue include:

• How well do the mechanical parameters in large-scale numerical models of Earth’s crust reflect what actually happens?
• To what degree can rocks weaken due to metamorphic and textural changes?
• How mechanically anisotropic is the crust in different areas?
• Can we predict the mechanical consequences of fluid infiltration into tectonically active areas?

Neighbor misorientations defining subgrains in quartz in a deformed granulite, determined through electron backscatter diffraction analysis. Maximum misorientation (red) is 3˚.

I approach these questions using chemical and textural microanalysis, numerical models, geochronology, and, most importantly, field observations.  Current projects include  investigating and quantifying weakening mechanisms in granulite and upper amphibolite facies domains of the Grenville Province along the shores of Georgian Bay, Ontario, and identifying the gross rheological structure of the crust under the New England Appalachians during the time of microcontinent collision.

In addition to rheological questions, I am interested in (1) better constraining the geological history of the New England Appalachians, and (2) using mineralogical information to address questions in other fields, including climate change and oceanography.  Work on Appalachian history improves our understanding of the area in which we live and allows us to better serve the citizens and visitors to the state, many of whom are drawn by Maine’s natural history.  As for the latter interest, much information related to climate change and marine chemical processes resides in particulate matter.  With modern microanalytical instrumentation, we have the capability of identifying and analyzing the particles, helping to answer previously unattainable questions.  This work relies on collaboration with others in the School of Marine Sciences and Climate Change Institute.

I also manage our new SEM laboratory, installed in May, 2009.  The laboratory consists of a Tescan Vega II XMU SEM, Gatan ChromaCL system, EDAX Genesis EDS system with and Apollo40 SDD, and a TSL EBSD system integrated with the EDS system.

Finally, as an affiliate of the Maine Center for Research in STEM Education, which offers the Master of Science in Teaching degree, I am involved in developing the next generation of teachers.  We work to ensure that their curricula are research-driven and represent the best teaching practices and content.