Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle
Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2009
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| Online Access: | http://hdl.handle.net/1721.1/44593 |
| _version_ | 1826195950081671168 |
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| author | Elsenbeck, James R |
| author2 | Mark Behn. |
| author_facet | Mark Behn. Elsenbeck, James R |
| author_sort | Elsenbeck, James R |
| collection | MIT |
| description | Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007. |
| first_indexed | 2024-09-23T10:18:23Z |
| format | Thesis |
| id | mit-1721.1/44593 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T10:18:23Z |
| publishDate | 2009 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/445932022-01-13T21:57:38Z Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle Elsenbeck, James R Mark Behn. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Earth, Atmospheric, and Planetary Sciences. /Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering. Woods Hole Oceanographic Institution. Ocean bottom Geology, Structural Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2007. Includes bibliographical references (p. 43-45). Grain size is an important material property that has significant effects on the viscosity, dominant deformation mechanism, attenuation, and shear wave velocity of the oceanic upper mantle. Several studies have investigated the kinetics of grain size evolution, but have yet to incorporate these evolution equations into large-scale flow models of the oceanic upper mantle. We construct self-consistent 1.5-D steady-state Couette flow models for the oceanic upper mantle to constrain how grain size evolves with depth assuming a composite diffusion-dislocation creep rheology. We investigate the importance of water content by examining end-member models for a dry, wet, and dehydrated mantle (with dehydration above -60-70 km depth). We find that grain size increases with depth, and varies with both plate age and water content. Specifically, the dehydration model predicts a grain size of -11 mm at a depth of 150 km for 75 Myr-old oceanic mantle. This results in a viscosity of -1019 Pa s, consistent with estimates from geoid and glacial rebound studies. We also find that deformation is dominated by dislocation creep beneath -60-70 km depth, in agreement with observations of seismic anisotropy in the oceanic upper mantle. The calculated grain size profiles are input into a Burger's model system to calculate seismic quality factor (Q) and shear wave velocity (Vs). For ages older than 50 Myrs, we find that Q and Vs predicted by the dehydration case best match seismic reference models for Q and the low seismic shear wave velocity zone (LVZ) observed in the oceanic upper mantle. by James R. Elsenbeck, II. S.M. 2009-02-17T17:23:48Z 2009-02-17T17:23:48Z 2007 Thesis http://hdl.handle.net/1721.1/44593 176630150 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 112 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Earth, Atmospheric, and Planetary Sciences. /Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering. Woods Hole Oceanographic Institution. Ocean bottom Geology, Structural Elsenbeck, James R Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| title | Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| title_full | Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| title_fullStr | Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| title_full_unstemmed | Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| title_short | Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| title_sort | influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle |
| topic | Earth, Atmospheric, and Planetary Sciences. /Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering. Woods Hole Oceanographic Institution. Ocean bottom Geology, Structural |
| url | http://hdl.handle.net/1721.1/44593 |
| work_keys_str_mv | AT elsenbeckjamesr influenceofgrainsizeevolutionandwatercontentontheseismicstructureoftheoceanicuppermantle |