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Diversity of Microfossils and Preservation of Thermally Altered Stromatolites from Anomalous Precambrian Paleoenvironments

Osterhout, Jeffrey T
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470753351

Abstract Details

2016, MS, University of Cincinnati, Arts and Sciences: Geology.
Studies of Precambrian life on Earth have been dominated by those of shallow marine deposits, and in order to gain a more complete picture of life’s early evolution it is important to consider a wider range of inhabited environments, including deep marine and terrestrial ecosystems. Evidence for early microbial life comes primarily from fossil microorganisms (microfossils), microbial sedimentary structures (e.g., stromatolites), and sedimentary organic matter (e.g., kerogen). The diversity and preservation of these different forms of fossil evidence introduces several challenges to their interpretation, requiring thorough analysis for accurately determining their biological origins. Investigating the paleobiology, organic geochemistry, and thermal maturity of such deposits provides a holistic approach to exploring the Precambrian biosphere in unfamiliar paleoenvironments. This thesis presents two studies of unique Precambrian ecosystems: a diverse microfossil assemblage from a 2.52-billion-year-old (Ga) deep marine deposit, and thermally altered stromatolites from a 1.4-billion-year-old evaporitic lacustrine deposit. Black cherts from the upper Gamohaan Formation (2.52 Ga) contain a consortium of organic-walled large and small coccoids, tubular filaments, and mat-like biofilm structures. Geochemical analyses of stromatolitic chert-carbonate from the Middlebrun Bay Member (1.4 Ga) in contact with a mafic sill show a trend in organic carbon isotopes relative to thermal maturity that is contrary to theoretical predictions. Findings from these studies reveal, for the first time, microfossil evidence of a diverse microbial community in the open Archean ocean prior to the Great Oxidation Event (GOE) ~2.4 billion years ago, and provide insight on the relationship between thermal maturity and organic carbon isotopes within a set of terrestrial stromatolites. Together, these studies help capture the enigmatic nature of the Precambrian fossil record and expand our full understanding of Earth’s early biosphere.
Andrew Czaja, Ph.D. (Committee Chair)
Julie K. Bartley, Ph.D. (Committee Member)
Carlton Brett, Ph.D. (Committee Member)
Aaron Diefendorf, Ph.D. (Committee Member)
111 p.
Planetology
Microfossils; Carbon isotopes; Kerogen; Precambrian; Raman spectroscopy; Thermal alteration

Recommended Citations

Citations

  • Osterhout, J. T. (2016). Diversity of Microfossils and Preservation of Thermally Altered Stromatolites from Anomalous Precambrian Paleoenvironments [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470753351

    APA Style (7th edition)

  • Osterhout, Jeffrey. Diversity of Microfossils and Preservation of Thermally Altered Stromatolites from Anomalous Precambrian Paleoenvironments. 2016. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470753351.

    MLA Style (8th edition)

  • Osterhout, Jeffrey. "Diversity of Microfossils and Preservation of Thermally Altered Stromatolites from Anomalous Precambrian Paleoenvironments." Master's thesis, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470753351

    Chicago Manual of Style (17th edition)

ucin1470753351
601
© 2016, some rights reserved.Creative Commons License Diversity of Microfossils and Preservation of Thermally Altered Stromatolites from Anomalous Precambrian Paleoenvironments by Jeffrey T Osterhout is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12