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Manganese: Minerals, Microbes, and the Evolution of Oxygenic Photosynthesis

Citation

Johnson, Jena Elaine (2015) Manganese: Minerals, Microbes, and the Evolution of Oxygenic Photosynthesis. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9RF5S0X. http://resolver.caltech.edu/CaltechTHESIS:05182015-162708844

Abstract

Oxygenic photosynthesis fundamentally transformed our planet by releasing molecular oxygen and altering major biogeochemical cycles, and this exceptional metabolism relies on a redox-active cubane cluster of four manganese atoms. Not only is manganese essential for producing oxygen, but manganese is also only oxidized by oxygen and oxygen-derived species. Thus the history of manganese oxidation provides a valuable perspective on our planet’s environmental past, the ancient availability of oxygen, and the evolution of oxygenic photosynthesis. Broadly, the general trends of the geologic record of manganese deposition is a chronicle of ancient manganese oxidation: manganese is introduced into the fluid Earth as Mn(II) and it will remain only a trace component in sedimentary rocks until it is oxidized, forming Mn(III,IV) insoluble precipitates that are concentrated in the rock record. Because these manganese oxides are highly favorable electron acceptors, they often undergo reduction in sediments through anaerobic respiration and abiotic reaction pathways.

The following dissertation presents five chapters investigating manganese cycling both by examining ancient examples of manganese enrichments in the geologic record and exploring the mineralogical products of various pathways of manganese oxide reduction that may occur in sediments. The first chapter explores the mineralogical record of manganese and reports abundant manganese reduction recorded in six representative manganese-enriched sedimentary sequences. This is followed by a second chapter that further analyzes the earliest significant manganese deposit 2.4 billon years ago, and determines that it predated the origin of oxygenic photosynthesis and thus is supporting evidence for manganese-oxidizing photosynthesis as an evolutionary precursor prior to oxygenic photosynthesis. The lack of oxygen during this early manganese deposition was partially established using oxygen-sensitive detrital grains, and so a third chapter delves into what these grains mean for oxygen constraints using a mathematical model. The fourth chapter returns to processes affecting manganese post-deposition, and explores the relationships between manganese mineral products and (bio)geochemical reduction processes to understand how various manganese minerals can reveal ancient environmental conditions and biological metabolisms. Finally, a fifth chapter considers whether manganese can be mobilized and enriched in sedimentary rocks and determines that manganese was concentrated secondarily in a 2.5 billion-year-old example from South Africa. Overall, this thesis demonstrates how microbial processes, namely photosynthesis and metal oxide-reducing metabolisms, are linked to and recorded in the rich complexity of the manganese mineralogical record.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:manganese, evolution of oxygenic photosynthesis, metal oxide respiration, mineralogical record of Mn
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geobiology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Fischer, Woodward W.
Thesis Committee:
  • Sessions, Alex L. (chair)
  • Fischer, Woodward W.
  • Newman, Dianne K.
  • Orphan, Victoria J.
  • Webb, Samuel M.
Defense Date:5 May 2015
Non-Caltech Author Email:johnson.jena.e (AT) gmail.com
Funders:
Funding AgencyGrant Number
National Science FoundationGraduate Research Fellowship
Packard FoundationUNSPECIFIED
Record Number:CaltechTHESIS:05182015-162708844
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05182015-162708844
DOI:10.7907/Z9RF5S0X
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1073/pnas.1305530110DOIArticle adapted for Chapter 2
http://dx.doi.org/10.1130/B30949.1DOIArticle adapted for Chapter 3
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8864
Collection:CaltechTHESIS
Deposited By: Jena Johnson
Deposited On:27 May 2015 21:25
Last Modified:06 Oct 2016 16:43

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