New Mexico Mineral Symposium — Abstracts

Different landing vehicles have explored five locations on the Martian surface in situ in addition to five surface mapping missions via satellite. Unlike mineralogical studies on Earth, determinative mineralogy on Mars has been limited to only a few analytical methods that were mounted on the probes. The most detailed studies of Martian mineralogy have been accomplished by studying Martian meteorites that were collected on Earth. This abstract reports on the proceedings of the "Workshop on Martian Sulfates as Recorders of Atmospheric-Fluid-Rock Interactions" held in Houston, Texas, on October 22-24, 2006, and will provide a comprehensive review of Martian mineralogy.

Analysis of meteorites and some limited spectral analysis indicate typical igneous rocks on Mars appear to be basalts and gabbros composed predominantly of olivine, pyroxene, chromite, magnetite, and plagioclase. Some feldspathoidal rocks may exist in the Columbia Hills region and include feldspathoid minerals and potentially assorted zeolites, although the direct mineralogy is not yet confirmed.

Analysis of Martian meteorites and limited compositional determinations using remote instruments (spectral analysis) indicate that Mars contains approximately 10 times greater amount of sulfur compared to crustal rocks of Earth. This high sulfur content appears to have allowed for the development of a wide suite of sulfate minerals on the surface. In contrast, the carbon cycle is much greater than the sulfur cycle on Earth, and carbonate minerals predominate in the surface environment. Table 1 summarizes the identified minerals from the Martian surface.

The origin of this sulfate is the subject of intense discussion and four models for sulfate formation have been proposed: (1) sulfates represent "gossans" formed by subareal weathering of sulfides; (2) impact excavation of sulfides and subsequent weathering; (3) volcanogenic mists; and (4) sulfuric-acid ground water. Regardless of the model, the presence of sulfate on the surface of Mars suggests the presence of water at some time in its history.