New observational and experimental evidence for a plume-fed asthenosphere boundary layer in mantle convection.

Morgan, J. P., Hasenclever, Jörg and Shi, C. (2013) New observational and experimental evidence for a plume-fed asthenosphere boundary layer in mantle convection. Earth and Planetary Science Letters, 366 . pp. 99-111. DOI 10.1016/j.epsl.2013.02.001.

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Abstract

The textbook view is that the asthenosphere is the place beneath the tectonic plates where competing temperature and pressure effects on mantle rheology result in the lowest viscosity region of Earth's mantle. We think the sub-oceanic asthenosphere exists for a different reason, that instead it is where rising plumes of hot mantle stall and spread out beneath the strong tectonic plates. Below this plume-fed asthenosphere is a thermal and density inversion with cooler underlying average-temperature mantle. Here we show several recent seismic studies that are consistent with a plume-fed asthenosphere. These include the seismic inferences that asthenosphere appears to resist being dragged down at subduction zones, that a sub-oceanic thermal inversion similar to 250-350 km deep is needed to explain the seismic velocity gradient there for an isochemical mantle, that a fast 'halo' of shear-wave travel-times surrounds the Hawaiian plume conduit, and that an apparent seismic reflector is found similar to 300 km beneath Pacific seafloor near Hawaii. We also present 2D axisymmetric and 3D numerical experiments that demonstrate these effects in internally consistent models with a plume-fed asthenosphere. If confirmed, the existence of a plume-fed asthenosphere will change our understanding of the dynamics of mantle convection and melting, and the links between surface plate motions and mantle convection

Document Type: Article
Additional Information: WOS:000319177100010
Keywords: mantle convection; mantle plume; asthenosphere; mantle seismology; SEISMIC ANISOTROPY; STRUCTURE BENEATH; TRANSITION ZONE; SS-PRECURSORS; DISCONTINUITY; EVOLUTION; ORIGIN; LITHOSPHERE; TEMPERATURE; SUBDUCTION
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2013.02.001
ISSN: 0012-821X
Date Deposited: 25 Jun 2013 05:55
Last Modified: 06 Mar 2017 13:35
URI: http://oceanrep.geomar.de/id/eprint/21438

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