Iceland plume

Iceland plume
Michael Ryan, U.S. Geological Survey. · Public domain · source
Name	Iceland plume
Type	Mantle plume / hotspot
Location	North Atlantic Ocean, Iceland
Coordinates	64°N 19°W
Elevation	Variable (mantle anomaly)
Last eruption	Ongoing mantle activity

Iceland plume The Iceland plume is a large mantle upwelling beneath the North Atlantic that has produced extensive magmatism, crustal accretion, and uplift in the region of Iceland and adjacent oceanic plateaus. It has been invoked to explain anomalously thick crust, high heat flow, and the presence of voluminous flood basalts such as the Iceland Flood Basalt Province during Paleogene opening of the North Atlantic. Research on the plume integrates data from seismic tomography, gravimetry, petrology, and plate reconstructions involving North American Plate and Eurasian Plate interactions.

Introduction

The mantle anomaly beneath the North Atlantic produced a locus of enhanced melting beneath Iceland and contributed to the formation of the North Atlantic Igneous Province. The plume concept stems from classical hotspot theory as advanced by researchers studying Hawaii and Reykjanes Ridge magmatism. The feature is central to debates about plume vs. non-plume origins of intraplate volcanism addressed by communities including investigators at Scripps Institution of Oceanography, University of Cambridge, University of Iceland, and US Geological Survey.

Geology and Structure

The subsurface structure beneath Iceland comprises anomalously thick oceanic crust, extended continental fragments, and flood basalts attributed to plume-driven melting during the Paleogene. Crustal thickness estimates from seismic studies by teams at Lamont–Doherty Earth Observatory and United States Antarctic Program indicate up to 40–65 km under central Iceland compared with typical oceanic crust. Lithospheric architecture includes the Iceland Rift System, fractured blocks, and northeast–southwest oriented transform segments inherited from Mid-Atlantic Ridge spreading. Mantle heterogeneity beneath the region is recorded by distinct isotopic domains similar to those documented in Greenland and Faroe Islands.

Tectonic Setting and Interaction with Mid-Atlantic Ridge

The plume lies near the divergent boundary between the North American Plate and the Eurasian Plate, intersecting the Mid-Atlantic Ridge where ridge–plume interaction modifies spreading processes. Ridge jumps, asymmetric spreading, and enhanced melt supply along the ridge axis are documented from bathymetric surveys by National Oceanic and Atmospheric Administration and from magnetic anomaly mapping by researchers at Geological Survey of Denmark and Greenland. Ridge–plume coupling has been invoked to explain the seaward propagation of the Reykjanes Ridge volcanic system and the segmentation of the ridge into volcanic rift zones correlated with plume thermal anomalies.

Volcanism and Surface Expressions

Surface manifestations include active central volcanoes such as Eyjafjallajökull, Katla, Hekla, and Bárðarbunga that lie along volcanic zones converging on the plume center. Flood basalt events such as the Paleogene North Atlantic Igneous Province produced extensive lava plains preserved in Iceland, Greenland, and the Faroe Islands, while subglacial eruptions have generated tuyas and jokulhlaups recorded during historical eruptions. Glacial–volcanic interactions during the Pleistocene produced distinctive tuyas like Herðubreið and widespread hyaloclastite deposits. Ongoing geothermal systems exploited at facilities such as Reykjanes Geothermal Power Station and Hellisheiði Power Station reflect high heat flow associated with the anomaly.

Geophysical and Geochemical Evidence

Seismic tomography from arrays deployed by International Ocean Discovery Program collaborators reveals low-velocity mantle anomalies extending from the transition zone to near-surface levels beneath Iceland. Gravity anomalies and crustal uplift measured by European Space Agency satellite altimetry and GPS networks indicate dynamic support consistent with a buoyant mantle source. Geochemical signatures in basaltic lavas show enriched isotopic components—He, Sr, Nd, Pb—similar to plume-influenced basalts observed at Hawaii and Icelandic Slope basalts; variations track source heterogeneity and recycled components linked to ancient subduction events recorded in North Atlantic mantle domains.

Formation Theories and Models

Competing models include a classical thermal plume rising from the lower mantle, a shallow asthenospheric upwelling amplified by lithospheric extension, and hybrid scenarios invoking detached thermochemical anomalies. Numerical mantle convection simulations developed at institutions such as ETH Zurich and California Institute of Technology test plume buoyancy, plume–slab interaction, and the influence of plate motions on melt production. Plate reconstructions incorporating data from Paleocene magnetic anomalies and flood basalt stratigraphy constrain the timing of plume initiation relative to the opening of the North Atlantic Ocean and the breakup of Laurussia and adjacent terranes.

Environmental and Societal Impacts

Plume-related volcanism has impacted climate through emissions during large eruptive episodes such as Paleogene flood basalt events correlated with transient cooling and biotic stress recorded in marine stratigraphy studied by Paleocene–Eocene Thermal Maximum researchers. Historical eruptions like the 2010 Eyjafjallajökull eruption disrupted aviation across Europe and highlighted hazards from ash dispersal. Geothermal resources derived from plume heat support renewable energy production at Icelandic facilities supplying a large fraction of local electricity and heating, underpinning infrastructure managed by entities such as Landsvirkjun. Hazard assessment, volcanic monitoring by Icelandic Meteorological Office, and multidisciplinary research continue to refine risk mitigation and understand long-term mantle processes.

Category:Geology of Iceland