Heat flow on the Hawaiian Swell and lithospheric reheating

Abstract

Most oceanic volcanic centres caused by hotspot activity are surrounded by sea floor that is unusually shallow for its age1,2. There is increasing evidence that swells found on older sea floor, like the Hawaiian Swell, have formed from a broad-scale reheating and thinning of the lithosphere as it passes over a mantle hotspot3,4. If the formation and subsequent disappearance of these swells are controlled by thermal processes, they should have an above-normal heat flux. We present here the results from 95 new heat flow measurements on the Hawaiian Swell. Along the older part of the swell the heat flow is 20–25% higher than the normal heat flow for crust of this age. This anomaly is consistent with the observed swell uplift. The shape and amplitude of the heat flow anomaly require that the reheating be largely confined to the lower half of the lithosphere.