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ShareScienceDaily (Aug. 1, 2007) — High-resolution images of Martian volcanoes have revealed areas that show signs of recent lava flow.
The youngest of these are about 2 million years old, as evidenced by the lack of impact craters on the flows. These flows are confined to Tharsis and Elysium, old volcanoes which exhibit a thickened crust compared to surrounding areas. Previous studies explain these recent volcanics by hypothesizing that strong mantle plumes arising from the core-mantle boundary fuel the melts, but the existence and sustainment of these plumes during the last few billion years is uncertain under Martian conditions.
Schumacher and Breuer propose a different hypothesis whereby the crust insulates the mantle, causing the mantle to cool slower than previously expected.
Through model simulations, they discover that a locally thickened crust with a reduced thermal conductivity and enriched in radioactive heat sources in comparison to the mantle could generate temperature variations in the upper mantle. These variations could form partial melts below this crustal lid, which, being more buoyant than surrounding material, could ooze out onto the Martian surface.
Title: An alternative mechanism for recent volcanism on Mars
Authors: Sandra Schumacher: Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Germany;
Doris Breuer: Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt, Berlin-Adlershof, Germany.
Source: Geophysical Research Letters (GRL) paper 10.1029/2007GL030083, 2007
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