Article Tags: Doug L. Hoffman
There have been a number of strange theories regarding the conditions deep within Earth’s interior circulating around the internet. Claims that solar flares will cause nuclear reactions deep below our feet are perhaps the most ludicrous, but fairly easy to dismiss. More timely, perhaps, is the sudden conversion of global warming guru Al Gore into a geothermal energy booster. Evidently Gore thinks it’s bad to drill for oil, but good to drill for heat. TV documentaries threaten mega-volcano and talk about mantle plumes underneath Hawaii, but just what does science tell us about our planet’s interior?
Gore, trying to explain geothermal energy to Conan O’Brien, stated that geothermal energy is plentiful because the Earth’s core temperature is millions of degrees. That’s not quite accurate, the inner core calculates out at about 4100 to 4200°C. Kei Hirose, from the Department of Earth and Planetary Sciences, Tokyo Institute of Technology, points out that the rocks and minerals of the deep mantle are not accessible in nature, except those occurring infrequently as inclusions in diamond. Writing in a perspective article in the January 8th issue of Science, Dr. Hirose explains that a paper by Tetsuo Irifune et al. in that same issue could have profound implications for predicting the properties and dynamics of the deep mantle.
“Recent such experimental investigations, as well as theoretical calculations, have suggested that the properties of lower-mantle minerals vary with increasing depth much more than was previously thought,” states Hirose. Irifune et al. report changes in mantle composition for conditions corresponding to depths below 1100 km involving iron (Fe) partitioning between the two main lower-mantle constituents, iron-magnesium silicate perovskite (Pv) and iron-magnesium oxide (ferropericlase, Fp).
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Source: theresilientearth.com