Variations in the oxygen fugacity of the Upper Mantle
Abstract/Contents
- Abstract
- Life thrives on our planet today because of the oxygen fugacity of the Earth's interior. Volcanic degassing of relatively oxidized C-O-H-S species helps sustain the oxygen-rich atmosphere that we breathe, while convection of reduced liquid Fe-Ni metal in the outer core generates the magnetic field that protects our planet from harmful radiation. On and within our planet alone, oxygen fugacity varies by over fifteen orders of magnitude, yet sub-log unit changes can have drastic effects on mineralogy, volatile speciation, and melting behavior within the Earth's mantle. In this thesis, I investigate the oxygen fugacity of upper mantle rocks (peridotites) dredged from the seafloor at convergent plate boundaries (subduction zones) and divergent plate boundaries (mid-ocean ridges). The first part of my thesis focuses on methodology—updating and refining the existing technique for determining oxygen fugacity in peridotites and demonstrating that this technique is applicable to even highly altered seafloor samples. In the remainder of the thesis, I present analyses of seafloor peridotites, primarily from the Tonga subduction zone in the South Pacific and the Southwest Indian Ridge in the southern Indian Ocean. My datasets are unique in that they document the oxygen fugacity of these geographic locations with unprecedented spatial density, allowing me to interrogate variability that was previously obscured by sparse global sampling. I show that the mantle beneath subduction zones gains its uniquely oxidized signature upon interaction with subduction-related melts and fluids. I additionally demonstrate that once changes related to a peridotite's thermal history are taken into account, mid-ocean ridge peridotites imply an average upper mantle oxygen fugacity consistent with that implied by mid-ocean ridge basaltic magmas. Finally, I show previously undocumented heterogeneity in the range of oxygen fugacity recorded by seafloor peridotites, indicating a vast complexity to the behavior of oxygen within our planet's interior.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2018; ©2018 |
| Publication date | 2018; 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Birner, Suzanne K |
|---|---|
| Degree supervisor | Mao, Wendy (Wendy Li-wen) |
| Degree supervisor | Warren, Jessica |
| Thesis advisor | Mao, Wendy (Wendy Li-wen) |
| Thesis advisor | Warren, Jessica |
| Thesis advisor | Brown, G. E. (Gordon E.), Jr |
| Thesis advisor | Cottrell, Elizabeth |
| Thesis advisor | Stebbins, Jonathan Farwell |
| Degree committee member | Brown, G. E. (Gordon E.), Jr |
| Degree committee member | Cottrell, Elizabeth |
| Degree committee member | Stebbins, Jonathan Farwell |
| Associated with | Stanford University, Department of Geological and Environmental Sciences. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Suzanne K. Birner. |
|---|---|
| Note | Submitted to the Department of Geological and Environmental Sciences. |
| Thesis | Thesis Ph.D. Stanford University 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Suzanne Birner
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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