Radial viscous fingering of hot asthenosphere within the Icelandic plume beneath the North Atlantic Ocean
© 2017 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...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/296649 2024-01-14T10:08:05+01:00 Radial viscous fingering of hot asthenosphere within the Icelandic plume beneath the North Atlantic Ocean Schoonman, CM White, NJ Pritchard, D 2017 application/pdf https://www.repository.cam.ac.uk/handle/1810/296649 https://doi.org/10.17863/CAM.43697 eng eng Elsevier BV http://dx.doi.org/10.1016/j.epsl.2017.03.036 Earth and Planetary Science Letters https://www.repository.cam.ac.uk/handle/1810/296649 doi:10.17863/CAM.43697 Attribution-NonCommercial-NoDerivatives 4.0 International https://creativecommons.org/licenses/by-nc-nd/4.0/ viscous fingering Iceland mantle plumes dynamic topography Article 2017 ftunivcam https://doi.org/10.17863/CAM.43697 2023-12-21T23:30:04Z © 2017 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), and that the asthenospheric channel is 100±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±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 ... Article in Journal/Newspaper Iceland North Atlantic Apollo - University of Cambridge Repository Norway Thumb ENVELOPE(-64.259,-64.259,-65.247,-65.247) |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
viscous fingering Iceland mantle plumes dynamic topography |
spellingShingle |
viscous fingering Iceland mantle plumes dynamic topography Schoonman, CM White, NJ Pritchard, D Radial viscous fingering of hot asthenosphere within the Icelandic plume beneath the North Atlantic Ocean |
topic_facet |
viscous fingering Iceland mantle plumes dynamic topography |
description |
© 2017 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), and that the asthenospheric channel is 100±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±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 ... |
format |
Article in Journal/Newspaper |
author |
Schoonman, CM White, NJ Pritchard, D |
author_facet |
Schoonman, CM White, NJ Pritchard, D |
author_sort |
Schoonman, CM |
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 BV |
publishDate |
2017 |
url |
https://www.repository.cam.ac.uk/handle/1810/296649 https://doi.org/10.17863/CAM.43697 |
long_lat |
ENVELOPE(-64.259,-64.259,-65.247,-65.247) |
geographic |
Norway Thumb |
geographic_facet |
Norway Thumb |
genre |
Iceland North Atlantic |
genre_facet |
Iceland North Atlantic |
op_relation |
https://www.repository.cam.ac.uk/handle/1810/296649 doi:10.17863/CAM.43697 |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 International https://creativecommons.org/licenses/by-nc-nd/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.43697 |
_version_ |
1788062512411836416 |