Grain boundary wetness of partially molten dunite
Samples of Fo[subscript 90] olivine and basaltic melt were annealed at a range of temperatures and a pressure of 1 GPa in a piston cylinder apparatus from 1 to 336 h. Post-run samples have melt contents from 0.3 to 6.8 % and mean grain sizes from 4.3 to 84.5 μm. Grain boundary wetness, a measure of...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Springer Berlin Heidelberg
2016
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| Online Access: | http://hdl.handle.net/1721.1/103170 |
| _version_ | 1826217220996333568 |
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| author | Mu, Shangshang Faul, Ulrich |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Mu, Shangshang Faul, Ulrich |
| author_sort | Mu, Shangshang |
| collection | MIT |
| description | Samples of Fo[subscript 90] olivine and basaltic melt were annealed at a range of temperatures and a pressure of 1 GPa in a piston cylinder apparatus from 1 to 336 h. Post-run samples have melt contents from 0.3 to 6.8 % and mean grain sizes from 4.3 to 84.5 μm. Grain boundary wetness, a measure of the intergranular melt distribution, was determined by analyzing scanning electron microscope images with sufficiently high resolution to detect thin layers wetting grain boundaries, as well as small triple junctions. The measurements show that grain boundary wetness increases with increasing melt content to values well above those predicted by the idealized isotropic equilibrium model for a finite dihedral angle. Additionally, the melt geometry changes with grain size, with grain boundary wetness increasing with increasing grain size at fixed melt content. Grain boundary wetness and dihedral angle of samples annealed at a range of temperatures, but constant melt content does not depend on temperature. These observations emphasize that the dihedral angle alone is not adequate to characterize the melt distribution in partially molten rocks, as the idealized isotropic model does not account for the influence of grain growth. Diffusion creep viscosities calculated from the measured wetness reflect the grain size and melt content dependence. Accordingly, experimentally measured viscosities at small grain sizes underestimate the effect of melt to weaken partially molten rocks for coarser grain sizes. The presence of melt in the mantle may therefore enhance diffusion creep relative to dislocation creep. |
| first_indexed | 2024-09-23T16:59:54Z |
| format | Article |
| id | mit-1721.1/103170 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T16:59:54Z |
| publishDate | 2016 |
| publisher | Springer Berlin Heidelberg |
| record_format | dspace |
| spelling | mit-1721.1/1031702022-09-29T22:59:48Z Grain boundary wetness of partially molten dunite Mu, Shangshang Faul, Ulrich Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Faul, Ulrich Samples of Fo[subscript 90] olivine and basaltic melt were annealed at a range of temperatures and a pressure of 1 GPa in a piston cylinder apparatus from 1 to 336 h. Post-run samples have melt contents from 0.3 to 6.8 % and mean grain sizes from 4.3 to 84.5 μm. Grain boundary wetness, a measure of the intergranular melt distribution, was determined by analyzing scanning electron microscope images with sufficiently high resolution to detect thin layers wetting grain boundaries, as well as small triple junctions. The measurements show that grain boundary wetness increases with increasing melt content to values well above those predicted by the idealized isotropic equilibrium model for a finite dihedral angle. Additionally, the melt geometry changes with grain size, with grain boundary wetness increasing with increasing grain size at fixed melt content. Grain boundary wetness and dihedral angle of samples annealed at a range of temperatures, but constant melt content does not depend on temperature. These observations emphasize that the dihedral angle alone is not adequate to characterize the melt distribution in partially molten rocks, as the idealized isotropic model does not account for the influence of grain growth. Diffusion creep viscosities calculated from the measured wetness reflect the grain size and melt content dependence. Accordingly, experimentally measured viscosities at small grain sizes underestimate the effect of melt to weaken partially molten rocks for coarser grain sizes. The presence of melt in the mantle may therefore enhance diffusion creep relative to dislocation creep. National Science Foundation (U.S.) (Grant EAR 838447) 2016-06-20T20:11:05Z 2017-03-01T16:14:49Z 2016-04 2016-05-31T12:13:17Z Article http://purl.org/eprint/type/JournalArticle 0010-7999 1432-0967 http://hdl.handle.net/1721.1/103170 Contributions to Mineralogy and Petrology. 2016 Apr 18;171(5):40 en http://dx.doi.org/10.1007/s00410-016-1250-z Contributions to Mineralogy and Petrology Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Springer-Verlag Berlin Heidelberg application/pdf Springer Berlin Heidelberg Springer Berlin Heidelberg |
| spellingShingle | Mu, Shangshang Faul, Ulrich Grain boundary wetness of partially molten dunite |
| title | Grain boundary wetness of partially molten dunite |
| title_full | Grain boundary wetness of partially molten dunite |
| title_fullStr | Grain boundary wetness of partially molten dunite |
| title_full_unstemmed | Grain boundary wetness of partially molten dunite |
| title_short | Grain boundary wetness of partially molten dunite |
| title_sort | grain boundary wetness of partially molten dunite |
| url | http://hdl.handle.net/1721.1/103170 |
| work_keys_str_mv | AT mushangshang grainboundarywetnessofpartiallymoltendunite AT faululrich grainboundarywetnessofpartiallymoltendunite |