Clark Wilson, UT Austin

The GRACE satellite mission (a University of Texas-led mission) was launched in 2002 and continues to provide a new view of Earth with its precise measurement of the global gravity field and month-to-month changes. The GRACE global mean gravity field has improved the accuracy and spatial resolution over previous results by orders of magnitude. However, it is the astounding ability of GRACE to see month to month changes in the field that has revolutionized many aspects of the Earth Sciences. GRACE is able to see monthly mass changes on Earth’s surface with a precision of about a centimeter layer of water, at a spatial resolution of a few hundred square kilometers. The result has been entirely new quantitative measures of regional and global water balance, ice sheet mass budgets, post-glacial rebound, earthquake displacement fields, and other phenomena.

Biography

Clark R. Wilson has been a Professor at the University of Texas at Austin since 1976, following studies in physics and geophysics at the University of California San Diego, and Scripps Institution of Oceanography. He has been a member of the Society of Exploration Geophysicists since 1969, of the American Geophysical Union since 1971, and was President of the Austin Geological Society 1983-84. He was Chairman of the UT Geological Sciences Department 1990-94 and 2004-07. From 1996-99 he was at NASA Headquarters, Washington DC, as Program Scientist for Geodynamics. Wilson was Geodynamics Section President of the International Association of Geodesy 2000-03, and is currently on the Directing Board of the International Earth Rotation and Reference Frames Service, and is Treasurer of UNAVCO, the GPS consortium of US universities.

Whitney Behr, UT Austin

The large-scale mechanical behavior of continental lithosphere in response to plate tectonic forces depends critically on the structure and rheology of planes of weakness within it (i.e. faults and associated shear zones). Because continental lithosphere is highly heterogeneous in composition, fault zone structure and rheology can be very complex and can show strong variations with depth. As a result, two questions related to continental deformation have remained unresolved for several decades:

1) What is the magnitude of the peak strength in the continental lithosphere and at what depth does the peak strength reside— the upper crust, lower crust or lithospheric mantle?

2) Although faults are narrow in the upper crust, what is their fate below the seismogenic layer where rocks transition from brittle deformation to ductile flow? Do they persist as narrow ductile shear zones, or at some depth do they sole into broadly distributed zones of ductile shear?

Experimental rock mechanics predicts specific answers to each of these questions, and these predictions can usefully be tested using a wide range of observations from different earth science fields, especially structural geology. In this talk I will briefly review the predictions about fault strength and structure that come from rock mechanics— then I’ll discuss past and ongoing research within my research group that aims to test these predictions through a range of observations of naturally deformed rocks derived from a wide range of depths and tectonic settings.

Biography

Whitney Behr is an Assistant Professor in the Department of Geological Sciences at JSG. She completed her Bachelor’s degree at California State University Northridge in 2006 and her Ph.D. at the University of Southern California in Los Angeles in 2011. She then spent 11 months at Brown University in Rhode Island as a Postdoctoral Fellow before joining the Jackson School in August, 2012. Whitney is a structural geologist whose research incorporates a variety of field, analytical and experimental techniques all aimed toward understanding continental deformation in both active and ancient orogenic systems. Whitney presently teaches several courses at UT, including undergraduate Structural Geology and Field Camp, as well as graduate courses Microstructures and Rock Rheology, Active Tectonics, and Tectonic Problems.

Jaime Barnes, UT Austin

Stable isotopes are excellent tracers of fluid sources and the extent of fluid-rock interaction in the crust and upper mantle. By tracing the source, we can make global mass balance calculations for volatile cycling on Earth. Determining volatile fluxes is critical to understanding the geochemical evolution of the Earth’s mantle and atmosphere and volcanic eruptive behavior. For my talk, I will trace volatile fluxes through subduction zones: from the initial hydration of the oceanic lithosphere, release of volatiles within the subduction zone, and the return of volatiles to the atmosphere through the volcanic front and to the Earth’s mantle within the dehydrated residual subducting slab.

Biography

Jaime Barnes is beginning her 6th year as an assistant professor in the Department of Geological Science at UT-Austin. Jaime is a stable isotope geochemist who uses stable isotopes as a geochemical tracer of fluids in various tectonic settings. Most of her research interests center around volatile cycling, metamorphism and volatile transport in subduction zones, serpentinization, and fluid-rock interactions and metasomatism in the high-temperature environment. However, she has been involved in a wide range of research, including the isotopic composition of lunar samples and hyperarid soils.

Jaime is a native Texan who received a B.S. in geology from UT, as well as, a B.A. in the Plan II Liberal Arts Honors Program. She completed a M.S., Ph.D., and post-doctoral fellowship at the University of New Mexico. Part of her post-doctoral fellowship was supported by a L’Oreal USA For Women in Science Fellowship. Jaime received the Subaru Outstanding Woman in Science award from the Geological Society of America in 2009. In 2011, she was selected as a member of the Society for Teaching Excellence at UT-Austin.