The origin of the assymetry in the Iceland hotspot along the Mid-Atlantic ridge from continental breakup to present-day

Abstract

The Iceland hotspot has interacted asymmetrically with the Mid-Atlantic ridge since continental breakup, influencing the Reykjanes Ridge over a greater distance to the south than the Aegir and Kolbeinsey Ridges to the north. We investigate causes of this asymmetry with 3D numerical models that simulate a mantle plume interacting with the evolving ridge system. Modeled maps of crustal thickness and plume influence indicate that asymmetrical influence along the ridge system is partially caused by the asymmetric ridge configuration relative to the hotspot center, and is either enhanced by variations thermal lithosphere thickness or largely unchanged when the lithosphere is created by extraction of water at the base of the melting zone. Comparisons of model predictions with geophysical estimates of asymmetry and crustal thickness variations along the ridges suggest the Iceland plume volume flux is 100-200 m3/s and the dehydration stiffens the upper mantle, but to a lesser degree than simulated.