Is Mercury a volatile-rich planet?
Abstract
Data returned from the gamma-ray spectrometer onboard the Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft have been interpreted to say that Mercury is a volatile-rich planet (elevated K/Th and K/U), which is important given its heliocentric distance. The MESSENGER X-ray spectrometer provided chemical information from the surface of Mercury which we used to calculate an average surface composition for the regions analyzed. The high S abundance and low FeO abundance of the surface indicates that the oxygen fugacity of the Mercurian interior is very reducing (-6.3 to -2.6 log fO2 units below the iron-wüstite buffer). At these low oxygen fugacities, elements that are typically considered lithophile can become more siderophile or chalcophile. We review available metal/silicate partitioning data for K and U to show that Mercury's volatile inventory is still an open question, and additional experiments investigating metal/silicate partitioning at the conditions of Mercury's core formation are needed.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- May 2012
- DOI:
- 10.1029/2012GL051711
- Bibcode:
- 2012GeoRL..39.9202M
- Keywords:
-
- Geochemistry: Composition of the planets;
- Geochemistry: Planetary geochemistry (5405;
- 5410;
- 5704;
- 5709;
- 6005;
- 6008);
- Mineralogy and Petrology: Experimental mineralogy and petrology;
- Planetary Sciences: Solar System Objects: Comparative planetology;
- Planetary Sciences: Solar System Objects: Mercury