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| Titel |
Plate tectonics on large exoplanets and the importance of the initial conditions |
| VerfasserIn |
Lena Noack, Doris Breuer |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078912
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| Zusammenfassung |
| Several numerical studies have been published in the past years speculating about the
existence of plate tectonics on large exoplanets. These studies focus on various aspects like
the mass of a planet [1,2,3,5], the interior heating rate and mantle temperatures [4,5] and the
occurrence of water in the upper mantle [6]. Different trends in the propensity for plate
tectonics have been observed in particular when varying the planetary mass: with increasing
mass the surface mobilization is found to be either more [2,3,5], equally [3,6] or less [1,4]
likely than on Earth. These studies and their implications are, however, difficult to
compare as they assume different initial conditions and parameter sets, and either
neglect the pressure effect on the viscosity or assume a rather small influence of the
pressure on the rheology. Furthermore, the thermal evolution of the planets (i.e.
cooling of core and decrease in radioactive heat sources with time) is typically
neglected.
In our study, we us the finite volume code GAIA [7] and apply a pseudo-plastic rheology.
We investigate how a strong pressure-dependence of the viscosity [8] influences not only the
convective regime in the lower mantle, but also the upper mantle and hence the likelihood to
obtain plate tectonics. We investigate how our results change when assuming different initial
conditions, focussing on the initial temperature in the lower mantle and at the core-mantle
boundary.
We find that the initial temperature conditions have a first-order influence on
the likelihood of plate tectonics on large exoplanets and (as observed in earlier
studies) surface mobilization may either be more, equally or less likely than on
Earth.
References
[1] O’Neill, C. and A. Lenardic (2007), GRL 34, 1-4.
[2] Valencia, D., O’Connell, R.J. and Sasselov, D.D. (2007), Astrophys. J. Let.,
670(1):45-48.
[3] van Heck, H.J. and Tackley, P.J. (2011), EPSL, 310:252-261.
[4] Stein, C.; A. Finnenkötter, J. P. Lowman and U. Hansen (2011), GRL 38, L21201.
[5] Foley, B.J., Bercovici, D. and Landuyt, W. (2012), EPSL 331-332, 281-290.
[6] Korenaga, J. (2010), Astrophys. J. Let. 725, L43-L46.
[7] Hüttig, C. and K. Stemmer (2008), PEPI 171, 137-146.
[8] Stamenkovic, V.; L. Noack, D. Breuer and T. Spohn (2012), Astroph. J. 748(1), 41. |
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