The compositional gradient of the planets is a first order observable which must be predicted by dynamical and chemical models. We assume that the position of the water vaporization front during accretion favored midplane enrichment by C-rich, anhydrous, presolar grain-rich interplanetary dust particles (C-IDPs) , and that a narrow inner annulus contributed much of Mercury's mass . We calculate solid mineral, and silicate liquid stability (at chemical equilibrium), for solar-composition vapor enriched in C-IDP type dust . At dust enrichments >100x, highly reduced assemblages including CaS and MgS will form above 1100K at total pressure 0.0001 bar. From this result, we predict that Mercury should contain more sulfur (in bulk) than Earth. This may affect mantle/core partitioning of elements with variable siderophile/chalcophile affinities, with consequences for Murcurian surface geochemistry. Signatures of this effect may be observable by NASA's MESSENGER mission. Similar arguments may apply to Jupiter's inner satellite Io.This work was supported by NASA, Office of Space Science, Cosmochemistry Program.  Messenger S., Keller L.P., Stadermann F.J., Walker R.M. and Zinner E. (2003) Samples of stars beyond the Solar System: Silicate grains in interplanetary dust. Science 300, 105-108.  Drake M.J. and Righter K. (2002) Determining the composition of the Earth. Nature 416: 39-44.  Ebel D.S. (2006) Condensaton of rocky material in astrophysical environments. In Meteorites and the Early Solar System II, (D. Lauretta et al., eds.) University Arizona, Tucson. p. 253-277 + 4 color plates.  Ebel D.S. and Alexander C.M.O'D. (2005) Condensation from cluster-idp enriched vapor inside the snow line: Implications for Mercury, asteroids, and enstatite chondrites. Lunar and Planetary Science XXXVI, Abs. #1797, LPI.
AAS/Division for Planetary Sciences Meeting Abstracts #39
- Pub Date:
- October 2007