Publication: The very early thermal state of Terra Cimmeria: Implications for magnetic
carriers in the crust of Mars
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2009
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Rosen Pub. Group
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Abstract
Large areas of strongly magnetized crust are located in Terra Cimmeria and Terra Sirenum, in the southern
highlands of Mars, the older terrains on the planet. The typical depth to the base of the magnetized
layer, deduced from the magnetic spectrum of Mars and modeling of isolated magnetic anomalies, would
40–60 km. In this paper the thermal state of Terra Cimmeria is revisited by calculating heat flows and
crustal geotherms consistent with a previous estimation of the effective elastic thickness of the lithosphere,
and with crustal abundances of heat-producing elements based on surface measurements performed
by the Mars Odyssey Gamma Ray Spectrometer. The results suggest that, at the time of
formation of the magnetized terrains surface (which have a minimum age of 4.1 Ga), Curie depths for
magnetite and hematite were shallower and similar, respectively, than the typical depth to the base of
the magnetized layer. This implies that hematite is an important (if not dominant) contributor to the
magnetization of the martian crust. However, an early warm climate would enhance the chance of magnetite
to be a significant, even dominant, magnetization carrier in the lower portion of the magnetic layer.