The thermal evolution of Mars as constrained by paleo-heat flows |
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Authors: | Javier Ruiz Patrick J McGovern Valle López Jean-Pierre Williams Rosa Tejero |
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Institution: | a Departamento de Geodinámica, Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, 28040 Madrid, Spain b Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058, USA c Instituto de Geología Económica, CSIC-UCM, 28040 Madrid, Spain d Instituto de Geociencias, CSIC-UCM, 28040 Madrid, Spain e Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095, USA f Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, USA |
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Abstract: | Lithospheric strength can be used to estimate the heat flow at the time when a given region was deformed, allowing us to constrain the thermal evolution of a planetary body. In this sense, the high (>300 km) effective elastic thickness of the lithosphere deduced from the very limited deflection caused by the north polar cap of Mars indicates a low surface heat flow for this region at the present time, a finding difficult to reconcile with thermal history models. This has started a debate on the current heat flow of Mars and the implications for the thermal evolution of the planet. Here we perform refined estimates of paleo-heat flow for 22 martian regions of different periods and geological context, derived from the effective elastic thickness of the lithosphere or from faulting depth beneath large thrust faults, by considering regional radioactive element abundances and realistic thermal conductivities for the crust and mantle lithosphere. For the calculations based on the effective elastic thickness of the lithosphere we also consider the respective contributions of crust and mantle lithosphere to the total lithospheric strength. The obtained surface heat flows are in general lower than the equivalent radioactive heat production of Mars at the corresponding times, suggesting a limited contribution from secular cooling to the heat flow during the majority of the history of Mars. This is contrary to the predictions from the majority of thermal history models, but is consistent with evidence suggesting a currently fluid core, limited secular contraction for Mars, and recent extensive volcanism. Moreover, the interior of Mars could even have been heating up during part of the thermal history of the planet. |
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Keywords: | Mars Mars Interior Thermal histories |
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