The distribution and origin of smooth plains on Mercury

Brett W. Denevi, Carolyn M. Ernst, Heather M. Meyer, Mark Robinson, Scott L. Murchie, Jennifer L. Whitten, James W. Head, Thomas R. Watters, Sean C. Solomon, Lillian R. Ostrach, Clark R. Chapman, Paul K. Byrne, Christian Klimczak, Patrick N. Peplowski

Research output: Contribution to journalArticlepeer-review

192 Scopus citations


Orbital images from the MESSENGER spacecraft show that ∼27% of Mercury's surface is covered by smooth plains, the majority (>65%) of which are interpreted to be volcanic in origin. Most smooth plains share the spectral characteristics of Mercury's northern smooth plains, suggesting they also share their magnesian alkali-basalt-like composition. A smaller fraction of smooth plains interpreted to be volcanic in nature have a lower reflectance and shallower spectral slope, suggesting more ultramafic compositions, an inference that implies high temperatures and high degrees of partial melting in magma source regions persisted through most of the duration of smooth plains formation. The knobby and hummocky plains surrounding the Caloris basin, known as Odin-type plains, occupy an additional 2% of Mercury's surface. The morphology of these plains and their color and stratigraphic relationships suggest that they formed as Caloris ejecta, although such an origin is in conflict with a straightforward interpretation of crater size-frequency distributions. If some fraction is volcanic, this added area would substantially increase the abundance of relatively young effusive deposits inferred to have more mafic compositions. Smooth plains are widespread on Mercury, but they are more heavily concentrated in the north and in the hemisphere surrounding Caloris. No simple relationship between plains distribution and crustal thickness or radioactive element distribution is observed. A likely volcanic origin for some older terrain on Mercury suggests that the uneven distribution of smooth plains may indicate differences in the emplacement age of large-scale volcanic deposits rather than differences in crustal formational process. Key Points ∼27% of Mercury is covered by smooth plains and >65% are volcanic in originThe circum-Caloris plains may be both Caloris ejecta and volcanic depositsThe asymmetry of smooth plains may be due to age rather than formational process

Original languageEnglish (US)
Pages (from-to)891-907
Number of pages17
JournalJournal of Geophysical Research: Planets
Issue number5
StatePublished - May 2013


  • Mercury
  • Smooth Plains
  • Volcanism

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


Dive into the research topics of 'The distribution and origin of smooth plains on Mercury'. Together they form a unique fingerprint.

Cite this