Research Note The Upper Mantle Beneath Iceland

The gravity field of Iceland, when studied in relation to seismic estimates of crustal thickness, suggests the presence of a substantial mass deficiency within the underlying upper mantle. An interpretation in harmony with the recently discovered delays in P-arrivals at Reykjavik is that there is large scale partial fusion within the upper mantle beneath Iceland. A 10 per cent magma-fraction of about 200 km vertical extent is the sort of magnitude required. The generation of magma on this scale can be understood if there is an uprising mantle convection current beneath Iceland.