Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean
The Icelandic mantle plume has had a significant influence on the geologic and oceanographic evolution of the North Atlantic Ocean during Cenozoic times. Full-waveform tomographic imaging of this region shows that the planform of this plume has a complex irregular shape with significant shear wave v...
Published in: | Earth and Planetary Science Letters |
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Language: | English |
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ftucambridgeesc:oai:eprints.esc.cam.ac.uk:3904 2023-05-15T17:32:37+02:00 Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean Schoonman, C. M. White, N. J. Pritchard, D. 2017 text http://eprints.esc.cam.ac.uk/3904/ http://eprints.esc.cam.ac.uk/3904/1/schoonman-et-al-2017.pdf http://www.sciencedirect.com/science/article/pii/S0012821X17301784 https://doi.org/10.1016/j.epsl.2017.03.036 en eng Elsevier http://eprints.esc.cam.ac.uk/3904/1/schoonman-et-al-2017.pdf Schoonman, C. M. and White, N. J. and Pritchard, D. (2017) Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean. Earth and Planetary Science Letters, 468. pp. 51-61. ISSN 0012-821X DOI https://doi.org/10.1016/j.epsl.2017.03.036 <https://doi.org/10.1016/j.epsl.2017.03.036> 02 - Geodynamics Geophysics and Tectonics Article PeerReviewed 2017 ftucambridgeesc https://doi.org/10.1016/j.epsl.2017.03.036 2020-08-27T18:09:49Z The Icelandic mantle plume has had a significant influence on the geologic and oceanographic evolution of the North Atlantic Ocean during Cenozoic times. Full-waveform tomographic imaging of this region shows that the planform of this plume has a complex irregular shape with significant shear wave velocity anomalies lying beneath the lithospheric plates at a depth of 100–200 km. The distribution of these anomalies suggests that about five horizontal fingers extend radially beneath the fringing continental margins. The best-imaged fingers lie beneath the British Isles and beneath western Norway where significant departures from crustal isostatic equilibrium have been measured. Here, we propose that these radial fingers are generated by a phenomenon known as the Saffman–Taylor instability. Experimental and theoretical analyses show that fingering occurs when a less viscous fluid is injected into a more viscous fluid. In radial, miscible fingering, the wavelength and number of fingers are controlled by the mobility ratio (i.e. the ratio of viscosities), by the Péclet number (i.e. the ratio of advective and diffusive transport rates), and by the thickness of the horizontal layer into which fluid is injected. We combine shear wave velocity estimates with residual depth measurements around the Atlantic margins to estimate the planform distribution of temperature and viscosity within a horizontal asthenospheric layer beneath the lithospheric plate. Our estimates suggest that the mobility ratio is at least 20–50, that the Péclet number is O(104)O(104), and that the asthenospheric channel is 100±20 km100±20 km thick. The existence and planform of fingering is consistent with experimental observations and with theoretical arguments. A useful rule of thumb is that the wavelength of fingering is 5±15±1 times the thickness of the horizontal layer. Our proposal has been further tested by examining plumes of different vigor and planform (e.g. Hawaii, Cape Verde, Yellowstone). Our results support the notion that dynamic topography of the Earth's surface can be influenced by fast, irregular horizontal flow within thin, but rapidly evolving, asthenospheric fingers. Article in Journal/Newspaper North Atlantic University of Cambridge, Department of Earth Sciences: ESC Publications Norway Thumb ENVELOPE(-64.259,-64.259,-65.247,-65.247) Earth and Planetary Science Letters 468 51 61 |
institution |
Open Polar |
collection |
University of Cambridge, Department of Earth Sciences: ESC Publications |
op_collection_id |
ftucambridgeesc |
language |
English |
topic |
02 - Geodynamics Geophysics and Tectonics |
spellingShingle |
02 - Geodynamics Geophysics and Tectonics Schoonman, C. M. White, N. J. Pritchard, D. Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean |
topic_facet |
02 - Geodynamics Geophysics and Tectonics |
description |
The Icelandic mantle plume has had a significant influence on the geologic and oceanographic evolution of the North Atlantic Ocean during Cenozoic times. Full-waveform tomographic imaging of this region shows that the planform of this plume has a complex irregular shape with significant shear wave velocity anomalies lying beneath the lithospheric plates at a depth of 100–200 km. The distribution of these anomalies suggests that about five horizontal fingers extend radially beneath the fringing continental margins. The best-imaged fingers lie beneath the British Isles and beneath western Norway where significant departures from crustal isostatic equilibrium have been measured. Here, we propose that these radial fingers are generated by a phenomenon known as the Saffman–Taylor instability. Experimental and theoretical analyses show that fingering occurs when a less viscous fluid is injected into a more viscous fluid. In radial, miscible fingering, the wavelength and number of fingers are controlled by the mobility ratio (i.e. the ratio of viscosities), by the Péclet number (i.e. the ratio of advective and diffusive transport rates), and by the thickness of the horizontal layer into which fluid is injected. We combine shear wave velocity estimates with residual depth measurements around the Atlantic margins to estimate the planform distribution of temperature and viscosity within a horizontal asthenospheric layer beneath the lithospheric plate. Our estimates suggest that the mobility ratio is at least 20–50, that the Péclet number is O(104)O(104), and that the asthenospheric channel is 100±20 km100±20 km thick. The existence and planform of fingering is consistent with experimental observations and with theoretical arguments. A useful rule of thumb is that the wavelength of fingering is 5±15±1 times the thickness of the horizontal layer. Our proposal has been further tested by examining plumes of different vigor and planform (e.g. Hawaii, Cape Verde, Yellowstone). Our results support the notion that dynamic topography of the Earth's surface can be influenced by fast, irregular horizontal flow within thin, but rapidly evolving, asthenospheric fingers. |
format |
Article in Journal/Newspaper |
author |
Schoonman, C. M. White, N. J. Pritchard, D. |
author_facet |
Schoonman, C. M. White, N. J. Pritchard, D. |
author_sort |
Schoonman, C. M. |
title |
Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean |
title_short |
Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean |
title_full |
Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean |
title_fullStr |
Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean |
title_full_unstemmed |
Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean |
title_sort |
radial viscous fingering of hot asthenosphere within the icelandic plume beneath the north atlantic ocean |
publisher |
Elsevier |
publishDate |
2017 |
url |
http://eprints.esc.cam.ac.uk/3904/ http://eprints.esc.cam.ac.uk/3904/1/schoonman-et-al-2017.pdf http://www.sciencedirect.com/science/article/pii/S0012821X17301784 https://doi.org/10.1016/j.epsl.2017.03.036 |
long_lat |
ENVELOPE(-64.259,-64.259,-65.247,-65.247) |
geographic |
Norway Thumb |
geographic_facet |
Norway Thumb |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://eprints.esc.cam.ac.uk/3904/1/schoonman-et-al-2017.pdf Schoonman, C. M. and White, N. J. and Pritchard, D. (2017) Radial Viscous Fingering of Hot Asthenosphere within the Icelandic Plume beneath the North Atlantic Ocean. Earth and Planetary Science Letters, 468. pp. 51-61. ISSN 0012-821X DOI https://doi.org/10.1016/j.epsl.2017.03.036 <https://doi.org/10.1016/j.epsl.2017.03.036> |
op_doi |
https://doi.org/10.1016/j.epsl.2017.03.036 |
container_title |
Earth and Planetary Science Letters |
container_volume |
468 |
container_start_page |
51 |
op_container_end_page |
61 |
_version_ |
1766130822000148480 |