Serpentinite Weathering and Implications for Mars

Introduction: In the search for life on Mars nearsurface soil environments may be important habitats for life accessible to future missions. Serpentinite rocks have been documented on Mars [1], as well as other clay minerals including smectite and kaolinites [2, 3]. Previous studies of soils formed on serpentinites on Earth have documented the formation of extensive clays, including smectite [4-9], vermiculite [7-10], chlorite [11], inter-layered chlorite-vermiculite [6], and kaolinite [5]. Serpentinites are additionally of interest as habitats for life such as methanogens [12]. Here we examine weathering of serpentinites from bedrock to soil surface, as a potential route for the formation of clay minerals on Mars from abundant ultramafic minerals. We additionally test for the presence of Feoxidizing bacteria in weathered serpentinite rocks. Feoxidizing bacteria have been previously demonstrated to affect dissolution rates of ultra-mafic minerals [13], and may produce important biosignatures [14].