Friday, 22 February 2008

Water Cycling in the Deep Earth - March 3rd

On Monday 3rd March, the University of Bristol has been lucky enough to be included in a lecture tour by the Mineralogical Society of America's distinguished lecturer, Dr Steve Jacobsen from the Department of Earth and Planetary Sciences, Northwestern University. His talk is designed to be accessible to a general audience, and you are welcome to come along.
13.00 hrs in the lecture theatre G25,
Department of Earth Sciences,
Wills Memorial Building University of Bristol

"Water Cycling in the Deep Earth:

Are the Oceans Just the Tip of the Iceberg?"
Earth is unique among the terrestrial planets in having liquid water on its surface. Water controls the character of biology and geology of the planet. Deep reservoirs of water incorporated as hydroxyl (OH-) into the solid silicate minerals of the mantle may contain the majority of the planet’s hydrogen and acted as buffers to maintain ocean volume and continental freeboard over geologic time.
Just two-tenths of one weight percent H2O in subducted oceanic crustal material and subsequently released to the hydrosphere is sufficient to recycle the total ocean volume about once in 4.6 billion years. It is possible that fluxes are several times this amount. Nominally anhydrous minerals of the transition zone (410-660 km depth) may serve as the largest internal reservoir. New and recent data on the effects of water on the physical properties of minerals indicates that hydration has a larger effect on seismic velocities than does temperature within their respective uncertainties.
This talk will explore how experimental studies are being used to constrain the effects of water on the physical properties of Earth materials at high pressures and temperatures, which may ultimately lead to seismological detection of water in the deep Earth. Experimental data, in concert with thermoelastic modelling may be used to interpret enigmatic S-wave velocity anomalies in the mantle reported from seismic tomography, such as the one recently detected beneath eastern North America.

If you would like to attend - just come along!

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