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S. Schumacher (Institute of Planetology, Westfaelische Wilhelms-Universitaet Muenster, 48149 Muenster, Germany), D. Breuer (Institute of Planetary Research, German Aerospace Center (DLR), 12489 Berlin, Germany)
New mapping of the Martian surface gives young ages in the range of just a few million years for some lava flows in the Tharsis and Elysium region. The explanation most often used for this ongoing volcanic activity on Mars is the existence of mantle plumes which cause molten material to rise from the deep mantle to the surface. However, on Mars the development of plumes and even more their continued sustainment is difficult to reconcile with what we know from the Martian interior as the temperature difference at the core-mantle boundary necessary to create a plume is small for today's conditions (< 50 K). The excess temperature of a potential plume compared to its surroundings at the base of the stagnant lid, which could cause a temperature increase in the crust, is even less. To explain volcanism, it is therefore important to look at temperature variations in the crust and upper mantle which could originate from different mechanisms than plumes. As the crust varies considerably on Mars - from about 70 km in the south to about 30 km in the north - and exhibits low thermal conductivities of approximately 2 Wm-1K-1, its influence on the temperature distribution cannot be neglected. This is especially true in the case of Tharsis, where a significant topography and deep roots lead to the highest crustal thickness of the planet. A thicker crust causes temperatures in the upper mantle to be higher than average, so the existence of a zone of partial melt underneath these regions is likely and a possible explanation for recent volcanism on Mars. In our 2-D simulations we examine the occurrence of a probable partial melt zone due to lateral variations in crustal thickness and topography.
This research was funded by the German Aerospace Center (DLR) under the project number 50QM0403.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.