37th DPS Meeting, 4-9 September 2005
Session 57 Moon, Mercury and Venus
Poster, Thursday, September 8, 2005, 6:00-7:15pm, Music Recital Room

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[57.11] Plate Recycling Driving Forces in Comparison on Terrestrial, Venusian and Martian Environments

J.J. Leitner, M.G. Firneis (Institute for Astronomy, University of Vienna)

In this paper we report on our theoretical calculations of the driving forces of plate recycling (trench pull and ridge push) for Venusian, Martian and Terrestrial environments. The application of a 2D model of a thermal convection cell in a fluid heated from below and with the restriction to very large Prandtl numbers [1] and by neglecting inertia-terms in the momentum equations and further by neglecting the heating of the descending lithosphere by friction in the terrestrial planets have resulted in discrete values for the two forces. On Earth the ratio between ridge push and trench pull is 1:13, which means that trench pull is about 13 times as potent as ridge push and therefore forms the dominant driving force. On Venus this ratio has been calculated to be 0.7:1, so that in contrast to Earth trench pull is not able to be a potent power for active plate-tectonics [2], a result which corresponds well with the MAGELLAN radar data set. For planet Mars the recent surface investigations point out that at present plate-tectonics is not operative, but it seems to be reasonable that in earlier times episodes of plate-recycling have occurred. Our model calculations have confirmed this assumption. They show that when presuming liquid surface water to be present, a plate-tectonics-driving-force-scenario is working. For the present Martian environment the inbalance of trench pull and ridge push is a very good indicator for the lack of active plate-tectonics.

We acknowledge support from OEFG (Oesterreischische Forschungsgesmeinschaft).

References: [1] Turcotte D.L., Schubert G., Geodynamics, Cambridge University Press (2002) [2] Leitner J.J., Firneis M.G., LPSC 2005, Abstract No. 1058 (2005)

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.