MAGMATISM IS ONE OF THE FEW GEOLOGIC PROCESSES TO PROVIDE MAJOR CHANGES AND ENERGY INFLUX TO THE MARTIAN SURFACE AND SUBSURFACE PAST THE NOACHIAN. ERUPTION AND DEGASSING OF MAFIC MAGMAS CONTRIBUTE TO THE SURFACE VOLATILE SPECIES AS WELL AS NUTRIENTS AND ENERGY THAT ARE NEEDED FOR BIOLOGICAL PROCESSES. AMONG THE VOLATILE SPECIES SULFUR IS ESPECIALLY IMPORTANT BECAUSE OF ITS SEVERAL REDOX STATES WHICH CAN BE UTILIZED AS AN ENERGY SOURCE BY CHEMOLITHOTROPHIC MICROORGANISMS. ON EARTH FEW MAFIC MAGMAS INTRUDE SULFUR-RICH SEDIMENTARY ROCKS. ON MARS HOWEVER SOILS HAVE BEEN FOUND TO CONTAIN ABUNDANT S-SPECIES AND THERE IS AMPLE EVIDENCE FOR ANCIENT MAGMATISM. THUS INTRUSION OF MAGMAS INTO SULFUR-RICH SOILS AND ROCKS IS TO BE EXPECTED ON MARS. THIS MAY BE PARTICULARLY RELEVANT TO THE PROPOSED LANDING SITES FOR THE NASA MARS 2020 AND FOR THE ESA EXOMARS MISSIONS AT MAWRTH VALLIS AND/OR JEZERO CRATER THAT HAVE A POTENTIAL VOLCANIC CAPPING UNIT DIRECTLY IN CONTACT WITH SULFATE-SEDIMENTS. IN THIS PROPOSAL WE WILL INVESTIGATE AN EARTH ANALOG IN THE SAN RAFAEL SWELL ON THE COLORADO PLATEAU FOR SUCH A SCENARIO OF MAFIC MAGMA INTRUDING GYPSUM-BEARING SEDIMENTS. WE HAVE OBSERVED NUMEROUS DIKES WHICH INTRUDED SULFUR RICH SEDIMENTS AND ARE WELL EXPOSED THROUGHOUT OUR FIELD-SITE. THEREFORE WE PROPOSE TO DO A DETAILED IN-SITU INVESTIGATION OF THE IGNEOUS INTRUSION AND METAMORPHOSED SEDIMENTS USING INSTRUMENTS THAT MIMIC THOSE ON ACTIVE AND FUTURE MISSIONS.