| Rock and Mineral Physics Lab | University of Minnesota | Dept of Geology & Geophysics |
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John W. KeefnerB.S., Geological Engineering, 2004, South Dakota School of Mines & Technology Research Specialist, University of Minnesota Contact Information
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| I am working at the University of Minnesota to investigate the effects
of oxygen fugacity on the viscosity of dunite. In short, the oxygen
fugacity - a measure of the chemical potential of oxygen - plays a major
role in how single olivine crystals flow under stress. My work considers
how oxygen fugacity effects the flow of Åheim dunite, a natural olivine
aggregate. The results of gas-medium deformation experiments will show a
dependence on oxygen fugacity that can be extrapolated to upper mantle
conditions. Such results are useful for workers wishing to further
constrain deformation experiments and also have implications for mantle
evolution on Earth and other terrestrial planets. I am also interested in planetary geology, especially systems on Mars. Astrobiology and meteorite studies are important avenues for discovering origins in the solar systems. Picture 1 (left) shows an "helectite bush" found in Wind Cave near Hot Springs, South Dakota. It is probably a biologically mediated formation, similar to a stromatolite, formed in an extremely low energy underwater, subsurface environment. Picture 2 (middle) is an L5 chondrite meteorite with a desert varnish, found in the Sahara, cut open and polished to reveal unique chondrules and iron-nickel melt pockets. The chemistry is similar to that of the Earth's mantle, but the chondritic texture is unlike any terrestrial rock found on the planet. Photo 3 (right) is an image of the moon taken with a 300mm lens at an f-stop of 11 on a 6.3 megapixel CCD and then cropped to its current size. The blurry picture is from aberrations in the lens. The moon's geology has provided great insight into the history of the solar system. Click on thumbnail for larger images.
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Freund, F.T., A. Takeuchi, B.W.S. Lau, R. Post, J. Keefner, A. Al-Manaseer, Stress-Induced Charges in the Electrical Conductivity of Igneous Rocks and the Generation of Ground Currents, Terrestrial Atmospheric and Oceanic Sciences special issue on “Anomalies in the Lithosphere, Atmosphere, and Ionosphere Associated with Earthquakes”, (print pending, 2004).
Keefner, J.W., B. Glover, Photon Propulsion for a Gossamer Spacecraft, Proceedings of the South Dakota Academy of Science, Vol. 82, 2003.
Keefner, J.W., L. Glover, Deployment of a Thin Membrane in Zero-G, Proceedings of the South Dakota Academy of Science, Vol. 80, 2001.
Keefner, J., M. Hanhardt, Zen & The Art of Diamagnetic Water Repulsion, 50th International Science & Engineering Fair, Science Service, Washington DC, 1999.
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