Uncertainty of mantle geophysical properties computed from phase equilibrium models. Issue 10 (31st May 2016)

• Record Type: Journal Article
• Authors: Connolly, J. A. D.; Khan, A.
• Is Part Of: Geophysical research letters. Volume 43:Issue 10(2016)
• Page Start: 5026
• Page End: 5034
• Publication Date: 2016-05-31
• Subjects: phase equilibria -- thermodynamics -- geophysics -- mantle composition -- mantle temperature -- uncertainty; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL068239
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Phase equilibrium models are used routinely to predict geophysically relevant mantle properties. A limitation of this approach is that nonlinearity of the phase equilibrium problem precludes direct assessment of the resultant uncertainties. To overcome this obstacle, we stochastically assess uncertainties along self‐consistent mantle adiabats for pyrolitic and basaltic bulk compositions to 2000 km depth. The dominant components of the uncertainty are the identity, composition and elastic properties of the minerals. For P wave speed and density, the latter components vary little, whereas the first is confined to the upper mantle. Consequently, P wave speeds, densities, and adiabatic temperatures and pressures predicted by phase equilibrium models are more uncertain in the upper mantle than in the lower mantle. In contrast, uncertainties in S wave speeds are dominated by the uncertainty in shear moduli and are approximately constant throughout the model depth range. Key Points: Uncertainties in mantle geophysical properties to 2000 km depth are assessed stochastically Uncertainty in P wave speed and density is greatest in the upper mantle Uncertainty in S wave speed is roughly constant with depth