Mars without the equilibrium rotational figure, Tharsis, and the remnant rotational figure

I. Matsuyama, M. Manga

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

We use a revised partitioning of the planet figure into equilibrium and nonequilibrium contributions that takes into account the presence of an elastic lithosphere to study the Martian gravity field and shape. The equilibrium contribution is associated with the present rotational figure, and the nonequilibrium contribution is dominated by Tharsis and a remnant rotational figure supported by the elastic lithosphere that traces the paleopole location prior to the formation of Tharsis. We calculate the probability density functions for Tharsis' size and location, the paleopole location, and the global average thickness of the elastic lithosphere at the time Tharsis was emplaced. Given the observed degree-3 spherical harmonic gravity coefficients, the expected Tharsis center location is 258.6 ± 4.2°E, 9.8 ± 0.9°N, where the uncertainties represent the 90% confidence interval. Given this Tharsis center location and the observed degree-2 spherical harmonic gravity coefficients, the expected paleopole location prior to the emplacement of Tharsis is 259.5 ± 49.5°E, 71.1-14.4 +17.5°N, and the expected elastic lithospheric thickness at the time of loading is 58-32+34 km. Our estimated paleopole colatitude implies 18.9-17.5+14.4° of true polar wander (TPW) driven by the emplacement of Tharsis, in disagreement with previous studies that invoke large TPW. The remnant rotational figure is visible in both the nonequilibrium degree-2 geoid (areoid) without Tharsis and the nonequilibrium degree-2 topography without Tharsis. The remnant rotational figure is also visible in the total nonequilibrium geoid without Tharsis, but it is not visible in the total nonequilibrium topography without Tharsis due to the strong signal of the north-south dichotomy. Shorter wavelength geological features become significantly more visible in the geoid with the removal of the long wavelength contributions of the equilibrium rotational figure, Tharsis, and the remnant rotational figure. Removal of the equilibrium rotational figure and Tharsis from the topography reveals a better defined north-south dichotomy boundary.

Original languageEnglish (US)
Article numberE12020
JournalJournal of Geophysical Research E: Planets
Volume115
Issue number12
DOIs
StatePublished - Dec 1 2010
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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