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The early thermal and magnetic state of the cratered highlands of Mars

Ruiz Pérez, Javier and McGovern , Patrick and Tejero López, Rosa María (2006) The early thermal and magnetic state of the cratered highlands of Mars. Earth and Planetary Science Letters, 241 . pp. 2-10.

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Abstract

Surface heat flows are calculated from elastic lithosphere thicknesses for the heavy cratered highlands of Mars, in terms of the
fraction of the surface heat flow derived from crustal heat sources. Previous heat flow estimations for Mars used linear thermal
gradients, which is equivalent to ignoring the existence of heat sources within the crust. We compute surface heat flows following a
methodology that relates effective thickness and curvature of an elastic plate with the strength envelope of the lithosphere, and
assuming crustal heat sources homogeneously distributed in a radioactive element-rich layer 20 or 60 km thick. The obtained
results show that the surface heat flow increases with the proportion of heat sources within the crust, and with the decrease of both
radioactive element-rich layer thickness and surface temperature. Also, the results permit us to calculate representative temperatures
for the crust base, rock strength for the upper mantle, and lower and upper limits to the crustal magnetization depth and
intensity, respectively. For Terra Cimmeria, an effective elastic thickness of 12 km implies between 30% and 80% of heat sources
located within the crust. In this case the uppermost mantle would be weak at the time of loading, and temperatures in the lower
crust cold enough to favor unrelaxed crustal thickness variations and to permit deep Curie depths in the highlands, as suggested by
the observational evidence.

Item Type:Article
Uncontrolled Keywords:Mars; Elastic thickness; Heat flow; Thermal structure; Curie depth
Subjects:Sciences > Geology > Geodynamics
ID Code:10500
Deposited On:23 Apr 2010 07:24
Last Modified:06 Feb 2014 08:44

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