%0 Journal Article
%A Ruiz Pérez, Javier
%T Giant impacts and the initiation of plate tectonics on terrestrial planets
%D 2011
%@ ISSN: 0032-0633
%U https://hdl.handle.net/20.500.14352/42355
%X Earth is the only terrestrial planet with present-day lithosphere recycling through plate tectonics.However, theoretical models of mantle convection based on general considerations find that all theterrestrial planets should be operating in the stagnant lid regime, in which the planets are one-platedand there is no lithosphere recycling. The stagnant lid regime is a consequence of the strong viscositycontrast across the convective layer, and therefore the upper lid (roughly equivalent to the lithosphere)must be sufficiently weakened in order to be mobilized. Here I propose that giant impacts could haveprovided the upper layer weakening required for surface recycling, and hence for plate tectonics, toinitiate on the early Earth. Additionally, giant impacts originated lithosphere thickness and densitydifferences, which might contribute to the initiation of subduction. Impacts are more energetic forEarth than for Mars, which could explain the likely early existence of plate tectonics on the Earthwhereas Mars never had lithosphere recycling. On the other hand, convection on Mercury and theMoon might be sluggish or even inexistent, implying a reduced influence of giant impacts on theirinternal dynamics, whereas there is no record of the earliest geological history of Venus, whichobscures any discussion on the influence of giant impacts on their internal dynamics.
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