Date of Award
Doctor of Philosophy (PhD)
Microbialites, sedimentary structures formed from the interaction of microorganisms with their environment, provide one of the oldest and most complete records of life on Earth, making them an invaluable tool in the field of geobiology. However, much of the information that could be gained from microbialites remains obscured due to our incomplete understanding of how variability in the microbial, geochemical, and physical processes driving their formation affect their morphological and geochemical characteristics. Modern environments of active microbialite formation provide the opportunity to study the relationship between variability in these environmental processes and the resultant mineral product and can act as an analog for understanding ancient examples. However, compared to the vast number of microbialites preserved in the geologic record, microbialite forming environments are relatively rare on modern Earth generating concerns about the generalizability of the knowledge gained from these environments and highlighting the need for study of additional modern settings. The work presented in this dissertation analyzes the processes controlling the formation, morphogenesis, and geochemical compositions of the microbialites of Laguna Negra, Argentina, a location which had previously been understudied compared to other modern environments.
Specifically, we investigated the processes controlling the megascale distributions of microbialites, the stable isotopic compositions of the carbonate minerals comprising the structures, and the lipid biomarker compositions preserved in the microbialites. Our results showed that each of these characteristics of microbialites reflect to varying degrees the biological, geochemical, and physical processes that control their formation. Overall, this work highlights the importance of a multifaceted approach to the analysis of microbialites integrating multiple lines of evidence in order to understand the processes controlling their formation and growth and provides a stronger framework for interpreting their meaning in the geologic record.
Chair and Committee
Alexander S. Bradley
Jeffrey G. Catalano, David A. Fike, Fernando J. Gomez, Bronwen L. Konecky,
Beeler, Scott Randall, "Understanding the Meaning of Microbialites as Geobiological Archives" (2019). Arts & Sciences Electronic Theses and Dissertations. 1870.