The tilted Iceland Plume and its effect on the North Atlantic evolution and magmatism

Iceland and the encompassing Northeast Atlantic are characterized by abundant volcanism, anomalously high topography and, in many places, anomalously thick basaltic crust. This has been attributed to the Iceland Plume, rising from the deep mantle, though its structure and very existence are debated. Using seismic waveform tomography with massive datasets, we compute a new, detailed model of the crust and upper mantle beneath Iceland and the surrounding North Atlantic region. The model reveals a large, low-velocity anomaly, indicative of high temperatures, at 400-660 kilometers depth beneath eastern Greenland, where seismic receiver functions also indicate an extensive high-temperature region. The anomaly rises upwards and eastwards toward Iceland, deflecting around the thick lithosphere of Greenland's cratons, which we also image in detail. We interpret the major low-velocity anomaly as the Iceland Plume, ascending from under Greenland and captured by the Mid-Atlantic Ridge. The ascent of the plume beneath the western Northeast Atlantic is consistent with its thin lithosphere, documented by our tomography, and abundant seamounts. Our results reconcile previously contrasting views on the structure of the Iceland Plume: while the plume is clearly visible in the transition zone beneath Greenland, it is confined to the upper mantle beneath Iceland. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Using seismic waveform tomography with massive datasets, a detailed model of the crust and upper mantle beneath Iceland and the surrounding North Atlantic region is computed. A large, low-velocity anomaly indicative of high temperatures at 400-660 kilometers depth beneath eastern Greenland is revealed, rising upwards towards Iceland. The major low-velocity anomaly is interpreted as the Iceland Plume, ascending from under Greenland and captured by the Mid-Atlantic Ridge.