A new look at the causes and consequences of the Icelandic hot-spot

Abstract

Summary New support for the hypothesis of a lower mantle plume rising near Iceland comes from recent developments in the theory of whole-mantle convection and is inferred from the large heat input required to support the major topographic swell which affects much of the N Atlantic and Greenland. The associated geoid and gravity highs are interpreted as due partly to the swell and its deep compensation and partly to the pressure anomaly caused by the plume. Rapid lateral migration of partially fused material from the plume in the asthenosphere prior to continental break-up caused the early Tertiary volcanism, with subsequent igneous activity concentrated at the ridge crest to form the Icelandic transverse ridge. Progressive expansion of the upper mantle thermal anomaly in response to pressure, in association with the complexities of plate evolution in this region, may account for the early uplift of S Greenland and later uplift of the Blosseville Kyst region. The low density upper mantle would also be expected to give rise to an anomalously high ridge-push force.