Publication Date:
2019
Description:
Abstract
We employ laboratory‐based grain‐size‐ and temperature‐sensitive rheological models to describe the viscoelastic behavior of terrestrial bodies with focus on Mars and its tidal response. We consider five rheological models, including Maxwell, extended Burgers, Andrade, Sundberg‐Cooper, and a power‐law approximation. However, the question of which model provides the most appropriate description of dissipation in planetary bodies, remains an open issue. To examine this, we build crust and mantle models of Mars (density and elasticity) that are computed self‐consistently through phase equilibrium calculations as a function of pressure, temperature, and bulk composition, whereas core properties are based on an Fe‐S parameterisation. We assess the compatibility of the viscoelastic models by inverting tidal response, mean density and moment of inertia of Mars for thermal, elastic, and attenuation structure. Our results show that although all viscoelastic models fit data, 1) their predictions for the tidal response at other periods and harmonic degrees are distinct, implying that our approach can be used to distinguish between the various models from seismic and/or tidal observations (e.g., with InSight). and 2) that Maxwell is only capable of fitting data for unrealistically low viscosities. All viscoelastic models converge upon similar interior structure models: large liquid cores (1750—1890 km in radius) that contain 17‐20.5 wt% S, and, consequently, no silicate perovskite‐dominated lower mantle. Finally, the methodology proposed here is generally formulated and applicable to other solar and extra‐solar system bodies where the study of tidal dissipation presents an important means for determining interior structure.
Print ISSN:
2169-9097
Electronic ISSN:
2169-9100
Topics:
Geosciences
,
Physics
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