Magnetotelluric investigation of the lower crust and upper mantle beneath Iceland

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M. Beblo
A. Bjornsson


Magnetotelluric measurements were made at 12 sites on a 210 km long profile in northern and eastern Iceland. The profile crosses areas of different geological age ranging from Tertiary flood basalt to the presently active zone of rifting and volcanism. Beneath the investigated area, at a depth of a few km down to about 20 km there exists a 5 km thick layer with low resistivity amounting to 15 Ωm which is imbedded between layers of higher resistivities. The depth to the low resistivity layer increases with increasing distance from the spreading axis. The low resistivity layer is presumably caused by partial melting at the base of the crust and at the top of the anomalous mantle beneath Iceland. Comparison with laboratory measurements confirms a basaltic composition and a temperature of 1,000-1,100° C of the good conductor, and probably partially molten peridotite in the upper mantle beneath. Mean temperature gradients in the crust calculated from the magnetotelluric data are in good agreement to surface temperature gradients measured in drill holes.

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Beblo, M., & Bjornsson, A. (1978). Magnetotelluric investigation of the lower crust and upper mantle beneath Iceland. Journal of Geophysics, 45(1), 1-16. Retrieved from


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