HR: 0800h
AN: U21B-0424    [Abstracts]
TI: Hydrogen and Mineral Elasticity: Modelling Hydration in the Earth's Interior
AU: * Smyth, J R
EM: smyth@colorado.edu
AF: University of Colorado, Department of Geological Sciences, Boulder, CO 80309-0399, United States
AU: Jacobsen, S D
EM: steven@earth.northwestern.edu
AF: Northwestern University, Department of Earth and Planetary Sciences, Evanston, IL 60208, United States
AB: Hydrogen is perhaps the most poorly constrained compositional variable in the Earth's interior. Hydrogen can enter all of the nominally anhydrous phases of the interior in trace, minor, or even major amounts. In order to include the effects of hydration in seismic and geodynamic models of the Earth's mantle it may be useful to identify a relatively simple relationship between elastic properties, bulk composition including H content, and crystal structure. We have identified a relation that predicts bulk modulus based on Birch's law for both hydrous and anhydrous silicate and oxide phases. The relation also holds for hydration of nominally anhydrous phases provided the volume of hydration is known. The resulting regression equation is: K = 2747 (ρ/M) – 308 (GPa) with a correlation coefficient of 98.5% , where ρ is density and M is mean atomic weight excluding hydrogen. A similar empirical relation predicts shear moduli with a correlation coefficient of 90% allowing rough modelling of the effects of hydration on Vp and Vs.
DE: 1025 Composition of the mantle
DE: 1042 Mineral and crystal chemistry (3620)
DE: 3600 MINERALOGY AND PETROLOGY
DE: 3919 Equations of state
DE: 7208 Mantle (1212, 1213, 8124)
SC: Union [U]
MN: 2007 Fall Meeting