MICROBE MINERAL INTERACTION IN SULFATE RICH PLAYAS AND THEIR RELEVANCE TO MARS

The samples with the highest priority for return will be the samples that contain potential life signatures. Sulfate-rich salts have been identified as a widespread component of Mars’ sedimentary deposits, illustrating the importance of near-surface hydrological processes on the planet. Playa environments with clear water components may be among the targets for sample return missions, as these samples may contain signatures of life. White Sands National Monument, a terrestrial analog, holds active playas that may contain different sized water bodies during the year. Besides modern playas, the Alkali Flat containes preserved deposits of Pleistocene Lake Otero (LO). Our intention is to use this range of environments and age to draw a comparison of these different environments and potential of preservation of organics in an evaporitic setting. Samples were extracted at 1m depths in the form of transects across the playas and an LO escarpment. Initially we used XRD to identify main mineral phases and SEM/EDS to decipher minor phases and biological morphologies. LO samples were predominantly composed of gypsum with minor quartz, while the modern playa Lake Lucero (LL) was predominantly gypsum, quartz and halite. The surface samples contained thenardite and clays. Biological morphologies were detected at both sites. LO site revealed preserved diatom shells and abundant presence of biofilm in the near surface sample. The LL site was less abundant in biofilm, with mineral precipitates (most frequently halite). It is difficult at this stage to make any conclusions however our findings will be presented and discussed at the conference.