THE DISCOVERY OF RELATIVELY LARGE DEPOSITS OF CARBONATE-BEARING MATERIALS IN THE NILI FOSSAE REGION OF MARS (EHLMANN ET AL. 2008) ADDRESSED PART OF THE LONG-STANDING QUESTION WHERE ARE THE MARTIAN CARBONATES? (LONGHI AND TAKAHASHI 2006). THESE DEPOSITS MAY NOT BE LARGE ENOUGH TO ACCOUNT FOR THE REQUIRED CO2 SEQUESTRATION TO EXPLAIN AN EARLY WARM/WET MARS WITH A THICKER ATMOSPHERE (EDWARDS AND EHLMANN 2015). THE CARBONATES WERE ORIGINALLY HYPOTHESIZED TO HAVE FORMED BY WEATHERING OR IMPACT INDUCED HYDROTHERMAL ALTERATION OF OLIVINE BEARING MATERIALS (EHLMANN ET AL. 2008). FORMATION BY SERPENTIZATION PROCESSES HAS ALSO BEEN PROPOSED (BROWN ET AL. 2010; VIVIANO ET AL. 2013) BASED ON THE INTERPRETATION THAT THE MG-OH BEARING MATERIALS IN EASTERN NILI FOSSAE ARE ASSOCIATED WITH TALC RATHER THAN MG-SMECTITE. THIS HYPOTHESIS HAS BEEN SUPPORTED BY SUBSEQUENT MODELING WORK BY VAN BERK AND FU (2011) WHO SIMULATED DIFFUSIVE TRANSPORT OF SUBSURFACE WATER UNDER A CO2 ATMOSPHERE AT MODERATE CONDITIONS FOR A PERIOD OF 100 000 YEARS AND FOUND LARGE AMOUNTS OF CARBONATE OVERLYING TALC WERE FORMED. IN ADDITION TO THE CARBONATE AND MG-OH CLAYS AN AL-OH BEARING UNIT HAS BEEN FOUND STRATIGRAPHICALLY ABOVE THE CARBONATE-BEARING LAYER (EHLMANN ET AL. 2009). THIS UNIT IS SCIENTIFICALLY IMPORTANT BECAUSE IT IS EASY TO DISTINGUISH SPECTRALLY FROM SURROUNDING MG-OHBEARING UNITS AND LIES BENEATH THE (SPECTRALLY FEATURELESS) CAPPING LAVAS OF SYRTIS MAJOR. IT IS UNCLEAR WHETHER IT FORMED IN THE SAME EVENT THAT FORMED THE UNDERLYING CARBONATES OR AS A LATER WEATHERING PRODUCT. THIS PROJECT WILL USE FULL RESOLUTION TARGETED (FRT) DATA FROM THE COMPACT RECONNAISSANCE IMAGING SPECTROMETER FOR MARS (CRISM) INSTRUMENT TO INVESTIGATE THE FOLLOWING THREE SCIENCE QUESTIONS THAT WILL TEST THE FORMATION HYPOTHESES FOR THE CARBONATE MATERIALS AT NILI FOSSAE:$237,223
· FY2020 · National Aeronautics and Space Administration