Publikationsdatum:
2015-09-02
Beschreibung:
Mercury experiences an uneven insolation that leads to significant latitudinal and longitudinal variations of its surface temperature. These variations, which are predominantly of spherical harmonic degree 2 and 4, propagate to depth, imposing a long-wavelength thermal perturbation throughout the mantle. We computed the accompanying density distribution and used it to calculate the mechanical and gravitational response of a spherical elastic shell overlying a quasi-hydrostatic mantle. We then compared the resulting geoid and surface deformation at degree-2 and 4 with Mercury's geoid and topography derived from MESSENGER data. More than 95% of the data can be accounted for if the thickness of the elastic lithosphere were between 110 and 180 km when the thermal anomaly was imposed. The obtained elastic thickness implies that Mercury became locked into its present 3:2 spin-orbit resonance later than about 1 Gyr after planetary formation.
Print ISSN:
0094-8276
Digitale ISSN:
1944-8007
Thema:
Geologie und Paläontologie
,
Physik
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