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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy<br />

(S) - <strong>IASPEI</strong> - International Association of Seismology and Physics of the Earth's<br />

Interior<br />

JSS001 Oral Presentation 1719<br />

Constraining the Composition and Thermal State of the Earth's Mantle<br />

from Inversion of Geophysical Date<br />

Dr. Amir Khan<br />

Niels Bohr Institute University of Copenhagen <strong>IASPEI</strong><br />

James Connolly, Nils Olsen<br />

We jointly invert seismic data (global ISC P and S wave travel times), electromagnetic sounding data<br />

(long-period inductive responses in the form of C-responses) and gravity data (mean mass and moment<br />

of inertia) using a recently developed method to rigorously invert different geophysical data jointly for<br />

compositional and thermal parameters. The inversion combines thermodynamic phase equilibrium<br />

calculation and physical properties, with a fully non-linear stochastic inverse algorithm, based on a<br />

Markov chain Monte Carlo (MCMC) method, to explore the range of model parameters consistent with<br />

the observations, i.e. Earth's mantle geotherm and composition within the system CaO-FeO-MgO-Al2O3-<br />

SiO2. Through our choice of parameters, the method provides a means of naturally linking various a<br />

priori unrelated geophysical data in the inversion. Our results are indicatative of a chondritic mantle<br />

composition and a lower mantle geothermal gradient that is slightly superabiabatic.<br />

Keywords: mantle, composition, temperature

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