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Older crust underlies Iceland.

Foulger, G.R. (2006) 'Older crust underlies Iceland.', Geophysical journal international., 165 (2). pp. 672-676.


The oldest rocks outcropping in northwest Iceland are ∼16 Myr old and in east Iceland ∼13 Myr. The full plate spreading rate in this region during the Cenozoic has been ∼2 cm a−1, and thus these rocks are expected to be separated by ∼290 km. They are, however, ∼500 km apart. The conclusion is inescapable that an expanse of older crust ∼210 km wide underlies Iceland, submerged beneath younger lavas. This conclusion is independent of any considerations regarding spreading ridge migrations, jumps, the simultaneous existence of multiple active ridges, three-dimensionality, or subsidence of the lava pile. Such complexities bear on the distribution and age of the older crust, but not on its existence or its width. If it is entirely oceanic its maximum age is most likely 26–37 Ma. It is at least 150 km in north–south extent, but may taper and extend beneath south Iceland. Part of it might be continental—a southerly extension of the Jan Mayen microcontinent. This older crust contributes significantly to crustal thickness beneath Iceland and the ∼40 km local thickness measured seismically is thus probably an overestimate of present-day steady-state crustal production at Iceland.

Item Type:Article
Keywords:Crust, Hotspot, Iceland, Microplate, Plume.
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Publisher statement:This article has been accepted for publication in Geophysical Journal International. © 2006 The Authors Journal compilation © 2006 RAS Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:No date available
Date deposited:27 February 2015
Date of first online publication:May 2006
Date first made open access:No date available

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