Planetary interior configuration control on thermal evolution and
geological history.
Abstract
The terrestrial planetary bodies display a wide variety of surface
expressions and histories of volcanic and tectonic, and magnetic
activity, even those planets with apparently similar dominant modes of
heat transport (e.g., conductive on Mercury, the Moon, and Mars). Each
body also experienced differentiation in its earliest evolution, which
may have led to density-stabilized layering in its mantle and a
heterogenous distribution of heat-producing elements. We explore the
hypothesis that mantle structure exerts an important control on the
occurrence and timing of geological processes such as volcanism and
tectonism. We investigate numerically the behavior of an idealized model
of a planetary body where heat-producing elements are assumed to be
sequestered in a stabilized layer at the top or bottom of the mantle. We
find that the mantle structure alters patterns of heat flow at the
boundaries of major heat reservoirs: the mantle and core. This modulates
the way in which heat production influences geological processes. In the
model, mantle structure is a dominant control on the relative timing of
fundamental processes such as volcanism, magnetic field generation, and
expansion/contraction, the record of which may be observable on
planetary body surfaces. We suggest that Mercury exhibits
characteristics of shallow sequestration of heat producing elements and
that Mars exhibits characteristics of deep sequestration.