Crustal recycling, mantle dehydration, and the thermal evolution of MarsReport as inadecuate

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* Corresponding author 1 German Aerospace Center DLR

Abstract : We have reinvestigated the coupled thermal and crustal evolution of Mars taking new laboratory data concerning the flow behavior of iron-rich olivine into account. with an early separation of geochemical reservoirs, models were required to show no episodes of crustal recycling. Furthermore, admissible models were required to reproduce the Martian crust formation history, to allow for the formation of partial melt under present day mantle conditions Taking dehydration stiffening of the mantle viscosity by the extraction of water from the mantle into account, we found that admissible models have low initial upper mantle temperatures around 1650 K, preferably a primordial crustal thickness of 30 km, and an initially wet mantle rheology. The crust formation process on Mars would then be driven by the extraction of a primordial crust after core formation, cooling the mantle to temperatures close to the peridotite solidus. According to this scenario, the second stage of global crust formation took place over a more extended period of time, waning at around , and was driven by heat produced by the decay of radioactive elements. Water extraction from the mantle was found to be relatively efficient and close to 40 percent of the total inventory was lost from the mantle in most models. Assuming an initial mantle water content of 100 ppm and that 10% of the extracted water is supplied to the surface, this amount is equivalent to a 15 m thick global surface layer, suggesting that volcanic outgassing of HO could have significantly influenced the early Martian climate and increased the planet-s habitability.

Keywords : Mars interior Thermal histories Volcanism Geophysics

Author: A. Morschhauser - M. Grott - D. Breuer -



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