Temperature Structure of the Icelandic Crust from Curie Point Depth

We present a Curie point depth map that casts light on the deep crustal temperature structure and can provide insights into the mechanisms of Iceland's formation. We used high-precision aeromagnetic anomaly data and a robust inversion algorithm. Curie point depth ranges from 4 to 28 km. The shallowest depths occur over the Reykjanes Peninsula and west and central Iceland. Curie point depth is relatively deep in north-central, south-central and eastern Iceland. The average thermal conductivity of the crustal magnetic layer, K, is 2.9 W/(m˚C). There is a weak inverse correlation between Curie point depth and 1026 heat flow measurement points. Mean heat flow is 170 mW/m². The base of the seismogenic layer from earthquakes in Iceland is generally slightly deeper than the Curie depth point. The supra-Curie point depth temperature gradient in Iceland is 20-80˚C/km. This may be compared with the average thermal gradient of oceanic crust of ~ 65˚C/km. In contrast, the sub-Curie point depth temperature gradient in the thick lower portion of the crust is significantly reduced – 10-35˚C/km, which is more typical of continental crust which has a median gradient of ~ 34˚C/km. Our results support the hypothesis that the 20-30 km thick lower crust of Iceland contains a substantial amount of continental material.