Is the Martian lithosphere sulfur rich?


  • Benton C. Clark,

  • A. K. Baird


It is proposed that the high sulfur measured in Martian fines may represent more than enrichment by upward migration of soluble sulfate salts. It may in fact reflect intrinsic surface abundances of S much higher than for the earth or moon. High S in the regolith is permitted by several alternative models including remnant primitive lithosphere, a primitive component in the regolith, or trapping of volcanic gases. The alternative models encompass various features of the accretion chemistry, thermal history, and core size-mass relationships that have been proposed for Mars. Possible consequences of ubiquitous sulfur include mantle mineral assemblages with unusual properties, significant sulfide content of unweathered rocks, high initial weathering rates and susceptibility to erosion of the surface, very high level of incorporation of H2O and O2 by surface fines, recycling of carbon and nitrogen, paleoclimatic effects of extinct atmospheric sulfur-containing gases, and a previous, if not contemporary, basis for biological activity without photosynthesis. The Martian regolith may also contain heavy volatile elements in relatively high abundance and a significant component of late accretionary material.