Moments of inertia and rotational stability of Mars: Lithospheric support of subhydrostatic rotational flattening

Bills, B. G.; James, Thomas S.

doi:10.1029/1998je900003

Cited by 20 publications

(26 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, recent Spirit data on Martian basalts (McSween et al 2004) and TES Surface Types I and II (McSween et al 2003) show compositions more terrestrial than the SNC meteorites, suggesting that these differences may not hold true for all Martian rocks. These observations are consistent with the moment of inertia calculations of Bills (1990) and Bills and James (1999) as well as melting experiments of Agee and Draper (2004) that suggest a less Fe-rich and more terrestriallike Martian mantle than the Dreibus and Wänke (1982) model Mars. The possibility that some Martian magmas may have more terrestrial characteristics demands a revisiting of the often used discrimination diagrams to assess whether or not the observed differences between Martian and terrestrial rocks are as robust as they have long been held to be.…”

Section: Introductionsupporting

confidence: 89%

The Mars/Earth dichotomy in Mg/Si and Al/Si ratios: Is it real?

Filiberto

Nekvasil

Lindsley

2006

American Mineralogist

View full text Add to dashboard Cite

The apparent dichotomy of Mg/Si and Al/Si ratios between terrestrial rocks and Martian meteorites has been interpreted as indicative of major differences between the terrestrial and Martian magma source regions. We suggest that this apparent dichotomy is not robust when compared with partly cumulate and non-cumulate terrestrial igneous material. Terrestrial cumulate intra-plate nodules with similar mineralogy to the SNC meteorites plot in the SNC fi eld in this compositional space and far removed from the "terrestrial geochemical fractionation" line (Earth's crust line) of Jagoutz et al. (1979). As is the case for terrestrial partly cumulate igneous rocks, the bulk compositions of cumulate SNC meteorites such Chassigny and Nakhla are dominated by the chemical characteristics of the accumulated minerals, minerals compositionally similar to those found in terrestrial intra-plate magmas. Therefore, the minor amounts of liquid involved play an insignifi cant role in the Mg/Si and Al/Si signature and no special Martian chemical characteristics can be identifi ed. SNC meteorites considered as possibly representative of liquid compositions are similar in composition and Mg/Si and Al/Si to terrestrial ferropicrites, suggesting that even "liquid" compositions within the SNC space are not uniquely Martian. Therefore, the Mg/Si and Al/Si ratios cannot clearly distinguish Martian from terrestrial rocks.

show abstract

Section: Introductionsupporting

confidence: 89%

The Mars/Earth dichotomy in Mg/Si and Al/Si ratios: Is it real?

Filiberto

Nekvasil

Lindsley

2006

American Mineralogist

View full text Add to dashboard Cite

show abstract

“…However, the nonhydrostatic theory is generally not suitable for planets with an elastic lithosphere like Mars. Bills and James [1999] noted that the present Martian rotational state is unstable in the framework of the nonhydrostatic theory. Daradich et al [2008] showed that the present Martian rotation pole is stable, as expected, with a revised partitioning into equilibrium and nonequilibrium contributions (hereafter nonequilibrium theory).…”

Section: Introductionmentioning

confidence: 93%

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

Matsuyama

Manga

2010

J. Geophys. Res.

View full text Add to dashboard Cite

[1] 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°o f 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.Citation: Matsuyama, I., and M. Manga (2010), Mars without the equilibrium rotational figure, Tharsis, and the remnant rotational figure,

show abstract

“…This study employs possible structure on Mars given by Bills and James (1999) same as Matsuyama et al (2006) used. The thickness of the lithosphere is close to the elastic thickness at the age of Tharsis uplift (Jellinek et al, 2008), which is consistent with that derived from a stochastic approach (Matsuyama and Manga, 2010).…”

Section: Invariable Parameters: Internal Structurementioning

confidence: 99%