Stevens, Eric W.2014-01-312014-01-312013-10https://hdl.handle.net/11299/162398University of Minnesota. M.S. thesis. October 2013. Major: Geology. Advisor: Jake V. Bailey. 1 computer file (PDF); vi, 52 pages.Barite (BaSO4) is found in certain benthic marine settings, sometimes in proximity to microbial mat communities. However, barite precipitation is typically thought to form from a mixing of sulfate and barium rich fluids. Barite mineral crusts collected from a brine pool in the Gulf of Mexico contain filamentous mineral structures of grossly similar morphology to filamentous surrounding sulfur-oxidizing Beggiatoa mats. Molecular analyses of DNA preserved in the Gulf of Mexico barite crusts suggest that microbial sulfur-oxidation could play a role in the formation of these authigenic precipitates. Laboratory experiments using several strains of benthic marine bacteria show that sulfide-oxidizing bacteria have the capability to mediate barite precipitation via the oxidation of reduced sulfur compounds to sulfate. The results of this study suggest that sulfide-oxidizing bacteria may play a role in the precipitation of certain marine barite deposits, and expands the potential role of bacteria in marine barite formation to include their potential to generate sulfate under sulfate-limited conditions, such as some brine fluids.en-USBariteBeggiatoaBrine poolMicrobial sulfur oxidationThesis or Dissertation