Iceland hotspot

Iceland hotspot
Name	Iceland hotspot
Type	Mantle plume / hotspot
Location	North Atlantic Ocean, near Iceland
Coordinates	64°N 18°W
Elevation	variable
Age	Cenozoic
Magma type	Basaltic to rhyolitic
Notable features	Reykjanes Ridge, Mid-Atlantic Ridge, Vatnajökull, Eyjafjallajökull

Iceland hotspot The Iceland hotspot is a major mantle upwelling beneath the North Atlantic region that has produced extensive Icelandic magmatism, large volcanic systems, and anomalous crustal growth along the Mid-Atlantic Ridge. It links processes observed at the Reykjanes Ridge, Greenland-Iceland-Faroe Ridge, and continental margins near Greenland and Scotland to mantle dynamics inferred from seismic tomography, geochemistry, and plate reconstructions. Studies involve institutions such as the United States Geological Survey, Norwegian Geological Survey, Icelandic Meteorological Office, and research projects like IODP and GEUS collaborations.

Geology and Origin

The feature is interpreted as a deep-seated mantle plume or a long-lived mantle anomaly that has interacted with the spreading axis of the Mid-Atlantic Ridge, producing thickened crust, elevated topography, and enhanced melt production beneath Iceland. Competing origin models include classical plume theories tied to the Cenozoic African and North American plate motions, shallow mantle heterogeneity linked to the North Atlantic Igneous Province, and edge-driven convection adjacent to the Laurentia margin. The hotspot has been correlated with the eruption history of the Jan Mayen volcanic island, the emplacement of the North Atlantic Igneous Province, and rift propagation events recorded in the Faroe Islands and Hebrides.

Tectonic Setting and Rift Interaction

Situated where the Eurasian Plate and North American Plate diverge, the feature modifies ridge segmentation, melt supply, and spreading rates along the Mid-Atlantic Ridge. Interaction with transform faults such as the Kolbeinsey Ridge and ridge jumps recorded near the Reykjanes Peninsula has influenced the locus of magmatism. Plate reconstructions involving the Iapetus Ocean closure, opening of the North Atlantic Ocean, and motions constrained by the HOTSPOT reference frame underpin models that tie excess volcanism to plume-ridge coupling, including asymmetrical crustal accretion observed toward the Jan Mayen Microcontinent.

Volcanism and Magmatism

Volcanic systems powered by the anomaly include central volcanoes with stratovolcano and fissure-swarm architectures such as Hekla, Katla, Bárðarbunga, and Krafla, as well as explosive systems like Eyjafjallajökull. Magma compositions span tholeiitic to alkalic basalts, with evolved dacitic and rhyolitic products at Askja and Öræfajökull due to crustal assimilation and fractional crystallization. Large flood basalt episodes tied to the Paleogene North Atlantic Igneous Province and more recent basaltic rift events along the Reykjanes Ridge document both plume-fed magma chambers and magma plumbing systems beneath Vatnajökull.

Geophysical and Geochemical Evidence

Seismic tomography from networks including the International Seismological Centre and regional arrays reveals low-velocity anomalies extending into the mantle transition zone beneath the region, consistent with hot, buoyant material. Gravity anomalies mapped by missions such as GRACE and crustal thickness studies using receiver functions show anomalously thickened crust and elevated topography compared with normal mid-ocean ridge segments. Geochemical signatures—high ratios of helium isotopes (elevated 3He/4He), trace element enrichment, and distinct lead-isotope systematics—link melts to deep mantle sources, comparable to signatures from Hawaii and Iceland-related plume provinces. Petrological studies from institutions like University of Iceland and University of Cambridge use melt inclusion and olivine-hosted analyses to quantify magma temperatures, pressures, and volatile contents.

Surface Expressions and Geomorphology

Surface manifestations include extensive lava fields (e.g., Eldhraun), shield volcanoes, fissure swarms (e.g., Laki), tuyas formed by subglacial eruptions (e.g., Herðubreið), and glacially modified calderas beneath ice caps such as Vatnajökull and Mýrdalsjökull. Rift-related grabens, hyaloclastite ridges, and tuyas illustrate interactions between magmatism and Pleistocene glaciation documented during the Last Glacial Maximum. Coastal basaltic plateaus, sea mounts like Surtsey, and submarine ridges along the Reykjanes Ridge record prolonged crustal accretion and erosional modification by North Atlantic currents and ice-sheet retreat tracked by the Icelandic Ice Core Project and marine stratigraphy studies.

Geological History and Evolution

Activity associated with the mantle anomaly began in the Paleogene during breakup of the North Atlantic and the development of the North Atlantic Igneous Province, producing voluminous flood basalts and initiating plume-ridge interaction. Subsequent Miocene–Quaternary evolution involved episodic plume pulses, ridge jumps, and construction of the modern Iceland edifice, punctuated by catastrophic events such as the Laki 1783–1784 eruptions and the 2010 Eyjafjallajökull eruption. Plate kinematic reconstructions using magnetic anomalies, sedimentary records, and biostratigraphy from the North Atlantic document ridge migration and hotspot track formation, including the formation of the Shona Ridge and the Greenland-Iceland-Faroe Ridge.

Impacts on Climate and Biodiversity

Large igneous provinces and high-flux eruptions tied to the plume have influenced paleoatmospheric composition and climate; sulfur and CO2 emissions from events like the Paleocene–Eocene Thermal Maximum-era volcanism have been implicated in short-term cooling and long-term greenhouse episodes. Historic eruptions such as Laki caused regional aerosol loading that impacted agriculture and mortality in Iceland, Scandinavia, and Europe, and contributed to documented climatic anomalies in the Little Ice Age timeframe. Ecosystem responses include primary succession on new lava fields studied by ecologists at University of Akureyri and colonization pathways for flora and fauna via North Atlantic dispersal routes involving Surtsey and coastal refugia during glacial cycles, with paleontological records preserved in peat bogs and lake cores from sites like Thingvellir.

Category:Volcanology Category:Geology of Iceland Category:Hotspots