Abstract | Understanding the origin and evolution of Mercury’s crust was a key goal
of the MESSENGER mission. Prior to MESSENGER’s exploration of Mercury, a
leading hypothesis for the formation of the planet’s crust was through
crystal–liquid fractionation of a magma ocean, leading to a plagioclase
flotation crust analogous to that of the Moon. However, reflectance
observations and elemental abundance data make it clear that Mercury’s
crust is very different from the Moon’s, and interpretations based on
the planet’s geomorphology and crater size–frequency distributions imply
widespread resurfacing occurred, likely through a combination of
volcanism and impact cratering. This geologic activity complicates an
examination of Mercury’s early crust. Here we present an investigation
of Mercury’s stratigraphy in order to evaluate the mode(s) of formation
of key crustal units. We explore whether the global occurrences and
regional variations are consistent with a graphite flotation crust, and
investigate the role of early volcanism in the formation of Mercury’s
crust. |
