Microbes and Mg: Investigating Stable Mg Isotope Fractionation in Microbally Mediated Carbonates

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dc.contributor.advisorChafetz, Henry S.
dc.contributor.committeeMemberLapen, Thomas J.
dc.contributor.committeeMemberGuidry, Sean A.
dc.creatorGabel, Thomas Christopher 1989-
dc.date.accessioned2018-02-15T19:43:23Z
dc.date.available2018-02-15T19:43:23Z
dc.date.createdDecember 2015
dc.date.issued2015-12
dc.date.submittedDecember 2015
dc.date.updated2018-02-15T19:43:23Z
dc.description.abstractMicrobially induced precipitation is a phenomenon in which minerals are precipitated as a byproduct of the metabolic processes and organic presence (e.g., biofilms) of microorganisms. Commonly responsible are consortia of eubacteria, archaebacteria, and fungi collaborating to complement each other’s metabolisms, exchange genetic material, and form the biofilms in which they live. The mineralized remains of these communities have been associated with carbonates in marine or lacustrine settings and, in addition, microbes have been either observed or suggested to be involved in the creation of speleothems, travertine deposits, various carbonate grains (e.g., ooids), and cements. Magnesium isotope compositions of carbonate minerals are sensitive to the mechanisms of carbonate mineral formation and diagenesis, Mg cycling, and environmental conditions. Data from laboratory experiments suggest that Mg isotope fractionations are dependent on precipitation rates and/or temperature. However, little work has been done to determine whether the information gleaned from sterile, abiotic precipitation experiments are valid if the magnesium bearing minerals are biotically induced. Calcite was precipitated in free drift experiments, conducted at 25 °C with Mg/Ca molar ratios between 0.2 and 5.6. Data from this study suggests that microbial activity during calcite precipitation influences Mg isotope fractionation in anaerobic environments. The calcite precipitated under these conditions was found to be enriched in 26Mg relative to calcite grown under anaerobic/sterile conditions as well as aerobic experiments with and without microorganisms. Further inferences were hampered by nonsystematic shifts in isotope measurements introduced by unresolvable organic materials associated with the Mg purification process, and possibly the culture media.
dc.description.departmentEarth and Atmospheric Sciences, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/10657/2144
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectMicrobially induced precipitation
dc.subjectBacterially induced precipitation
dc.subjectMg isotope fractionation
dc.subjectMagnesium isotope fractionation
dc.titleMicrobes and Mg: Investigating Stable Mg Isotope Fractionation in Microbally Mediated Carbonates
dc.type.dcmiText
dc.type.genreThesis
thesis.degree.collegeCollege of Natural Sciences and Mathematics
thesis.degree.departmentEarth and Atmospheric Sciences, Department of
thesis.degree.disciplineGeology
thesis.degree.grantorUniversity of Houston
thesis.degree.levelMasters
thesis.degree.nameMaster of Science

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