Ocean Island Densities and Models of Lithospheric Flexure
Ocean Island Densities and Models of Lithospheric Flexure
Estimates of the effective elastic thickness (Te) of the oceanic lithosphere based on gravity and bathymetric data from island loads are commonly significantly lower than those based on the wavelength of plate bending at subduction zones. The anomalously low values for ocean islands have been attributed to the finite yield strength of the lithosphere, to erosion of the mechanical boundary layer by mantle plumes, to pre-existing thermal stresses, and to overprinting of old volcanic loads by younger ones. A fifth possible contribution to the discrepancy is an incorrect assumption about the density of volcanic loads. We suggest that load densities have been systematically overestimated in studies of lithospheric flexure, potentially resulting in systematic underestimation of effective elastic thicknesses and overestimation of the effects of hotspot volcanism. We illustrate the effect of underestimating load density with synthetic examples and an example from the Marquesas Islands. This effect, combined with the other effects listed above, in many cases may obviate the need to invoke hotspot reheating to explain low apparent elastic thicknesses.
gravity anomalies, density, flexure of the lithosphere, volcanic structure, rheology
731-739
Minshull, Tim
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Charvis, P.
308a8412-da90-475b-991d-37e5f91a9d66
2001
Minshull, Tim
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Charvis, P.
308a8412-da90-475b-991d-37e5f91a9d66
Minshull, Tim and Charvis, P.
(2001)
Ocean Island Densities and Models of Lithospheric Flexure.
Geophysical Journal International, 145 (3), .
(doi:10.1046/j.0956-540x.2001.01422.x).
Abstract
Estimates of the effective elastic thickness (Te) of the oceanic lithosphere based on gravity and bathymetric data from island loads are commonly significantly lower than those based on the wavelength of plate bending at subduction zones. The anomalously low values for ocean islands have been attributed to the finite yield strength of the lithosphere, to erosion of the mechanical boundary layer by mantle plumes, to pre-existing thermal stresses, and to overprinting of old volcanic loads by younger ones. A fifth possible contribution to the discrepancy is an incorrect assumption about the density of volcanic loads. We suggest that load densities have been systematically overestimated in studies of lithospheric flexure, potentially resulting in systematic underestimation of effective elastic thicknesses and overestimation of the effects of hotspot volcanism. We illustrate the effect of underestimating load density with synthetic examples and an example from the Marquesas Islands. This effect, combined with the other effects listed above, in many cases may obviate the need to invoke hotspot reheating to explain low apparent elastic thicknesses.
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Published date: 2001
Additional Information:
Short title: Ocean island densities
T. A. Minshull, School of Ocean and Earth Science, University of Southampton, Southampton Oceanography Centre, European Way, Southampton SO14 3ZH, U.K.
Ph. Charvis, Unité Mixte de Recherche Géosciences Azur, Institut de Recherche pour le Développement (IRD), BP48, 06235, Villefranche-sur-mer, France.
Keywords:
gravity anomalies, density, flexure of the lithosphere, volcanic structure, rheology
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Local EPrints ID: 114
URI: http://eprints.soton.ac.uk/id/eprint/114
ISSN: 0956-540X
PURE UUID: e7315464-2c7b-4935-97da-ebd17be5c399
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Date deposited: 31 Jul 2003
Last modified: 16 Mar 2024 03:11
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P. Charvis
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