Show simple item record

dc.contributor.authorSchoonman, Charlotteen
dc.contributor.authorWhite, Nicholasen
dc.contributor.authorPritchard, Den
dc.date.accessioned2019-09-09T23:30:28Z
dc.date.available2019-09-09T23:30:28Z
dc.date.issued2017-06-15en
dc.identifier.issn0012-821X
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/296649
dc.description.abstract© 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 Earth's surface can be influenced by fast, irregular horizontal flow within thin, but rapidly evolving, asthenospheric fingers.
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.titleRadial viscous fingering of hot asthenosphere within the Icelandic plume beneath the North Atlantic Oceanen
dc.typeArticle
prism.publicationDate2017en
prism.publicationNameEarth and Planetary Science Lettersen
prism.volume468en
dc.identifier.doi10.17863/CAM.43697
dcterms.dateAccepted2017-03-29en
rioxxterms.versionofrecord10.1016/j.epsl.2017.03.036en
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2017-06-15en
dc.contributor.orcidSchoonman, Charlotte [0000-0002-2882-9916]
dc.identifier.eissn1385-013X
rioxxterms.typeJournal Article/Reviewen
cam.issuedOnline2017-04-13en
rioxxterms.freetoread.startdate2018-06-15


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record

Attribution-NonCommercial-NoDerivatives 4.0 International
Except where otherwise noted, this item's licence is described as Attribution-NonCommercial-NoDerivatives 4.0 International