Crustal structure of the Iceland-Faeroe Ridge

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M.H.P. Bott
K. Gunnarsson


Knowledge of the crustal structure of the Iceland-Faeroe Ridge is based on results from the North Atlantic Seismic Project of 1972 supplemented by earlier short refraction lines and reflection, gravity and magnetic surveys. The main 5. 7 km/s upper crustal layer is locally overlain by lower velocity layers of variable thickness. The upper crust is interpreted as being predominantly basaltic, comprising lavas, regions of pyroclastic rock and intrusives including ring complexes. A 6.7 km/s lower crustal layer underlies the upper crust at a depth of between about 4 and 8 km along the Ridge; this layer is present also beneath the Icelandic shelf but not beneath the Faeroe shelf. A deeper 7.8 km/s refractor interpreted as the Moho occurs at about 30-35 km depth beneath the south-eastern part of the Ridge, shallowing to about 28 km towards the north-western end of it. A significant increase in velocity with depth within the main 6.7 km/s layer has not been detected but may occur, in which case the Moho would be somewhat deeper. The seismic crustal results are consistent with a gravity profile across the Ridge, which indicates approximate Airy isostatic equilibrium. The crust beneath the Ridge, which is of a thickness more typical of the continents than the oceans, is believed to have been formed by sea-floor spreading during the period 55 to 40 Ma ago.

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Bott, M., & Gunnarsson, K. (1980). Crustal structure of the Iceland-Faeroe Ridge. Journal of Geophysics, 47(1), 221-227. Retrieved from


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