ISGS Seminar Series: Oxidation of Sulfide Minerals: from Acid Mine Drainage to Life on Mars
Department of Geology
Southern Illinois University, Carbondale
Pyrite is the most abundant metal sulfide in nature and, therefore, has a major influence on the biogeochemical cycles of iron, sulfur, and oxygen. Oxidation of sulfide minerals near the Earth’s surface in the presence of water and oxygen frequently results in production of highly acidic, sulfate-rich solutions known as acid drainage (AD). Acid drainage is commonly associated with the extraction and processing of sulfide-bearing metalliferous ore deposits, sulfide-rich coal, and weathering of metalliferous black shales.
Recently, much interest has focused on sulfide oxidation due to the discovery of sulfate minerals on Mars and the similarity of Martian mineral assemblages with minerals associated with AD on Earth. Furthermore, the intrinsic association of sulfate minerals with liquid water is consistent with surface or near-surface water being present during Martian history. Various scenarios have been proposed for sulfate formation on Mars, including hydrothermal alteration, precipitation from evaporating brines, and volcanic aerosols. However, to date, there is no comprehensive understanding of the oxidative mechanism which satisfactory explains all the observed features. By studying Earth-analog habitats, such as the AD environments and the biological communities associated with them on Earth, we have a unique opportunity to understand both extreme environments here on Earth, including the self-contained biomes, and habitability potential of Mars.