Mantle plume

Mantle plume
Name	Mantle plume
Type	Geological phenomenon
Region	Global

Mantle plume is a hypothesized upwelling of anomalously hot rock that rises from deep within the Earth to produce localized melting, volcanism, and lithospheric uplift. Proposed to explain intraplate volcanism and large igneous provinces, the mantle plume concept connects observations from Hawaii, Iceland, Deccan Traps, and Yellowstone National Park with geophysical and geochemical data collected across global platforms such as the Ocean Drilling Program, Integrated Ocean Drilling Program, and International Continental Scientific Drilling Program. Advocates often invoke deep mantle sources linked to downwelling and chemical heterogeneities preserved since the formation of the Moon-forming impact and early Proterozoic mantle differentiation.

Overview and definition

In the canonical formulation introduced by W. Jason Morgan in 1971, a mantle plume is defined as a narrow, buoyant column of hot material rising from near the core–mantle boundary to the base of the lithosphere, producing a long-lived thermal anomaly and a chain of volcanic centers as the overlying lithospheric plate moves relative to the plume. The idea is embedded in debates about Alfred Wegener-era continental drift versus modern plate tectonics and interacts with paradigms developed at institutions such as the Scripps Institution of Oceanography, Lamont–Doherty Earth Observatory, and US Geological Survey. Key examples often cited include volcanic provinces associated with Hawaiian Islands, Galápagos Islands, Réunion, Easter Island, and Iceland.

Formation and physical characteristics

Plume formation models invoke thermal or compositional buoyancy arising from thermal boundary layer instabilities at the core–mantle boundary or from enriched domains such as the proposed LLSVPs beneath Africa and Pacific Ocean. Numerical simulations using codes developed at Massachusetts Institute of Technology, California Institute of Technology, and ETH Zurich generate plume heads and tails whose dynamics are compared with laboratory analogues from facilities like the Cornell University experimental geophysics labs and University of Cambridge convection tanks. Physical characteristics include elevated temperatures inferred from seismic anomalies measured by networks such as the IRIS and instruments at Geological Survey of Canada, and compositional signatures discerned by geochemists at University of Oxford and Stanford University. Plumes are hypothesized to produce initial large head events that create flood basalts and subsequent narrow tails responsible for hotspot tracks like those mapped across the Hawaiian–Emperor seamount chain.

Evidence and observational methods

Support for plumes comes from multiple lines of evidence using methods developed by teams at USGS, British Geological Survey, Geological Survey of India, and academic centers. Seismic tomography studies from Princeton University, University of Cambridge, University of Tokyo, and ETH Zurich identify low seismic velocity zones beneath Iceland, Hawaii, and Afro-Arabian regions. Geochemical evidence from isotopic systems such as helium, lead, strontium, and neodymium processed at Lamont–Doherty Earth Observatory, University of California, Berkeley, and Carnegie Institution for Science point to primitive reservoirs and deep-sourced melts beneath intraplate volcanoes like Loihi, Kilauea, and Mauna Loa. Geodetic observations using GPS networks maintained by European Space Agency and NASA detect surface uplift and deformation consistent with thermal buoyancy; gravity data from missions such as GRACE supplement inferences about mass anomalies. Drilling campaigns by IODP and palaeomagnetic reconstructions by groups at University of Washington and University of Edinburgh correlate age-progressive volcanic chains with plate motions.

Geological manifestations (hotspots and flood basalts)

Manifestations attributed to plumes include long-lived hotspots that produce island chains and seamounts (e.g., Hawaii, Galápagos, Canary Islands, Azores, Socotra), continental rifting and large igneous provinces such as the Deccan Traps, Siberian Traps, Karoo-Ferrar, Columbia River Basalt Group, and the Ontong Java Plateau. Episodes like the Cretaceous–Paleogene boundary volcanism and mass extinctions are sometimes temporally associated with plume-related flood basalt eruptions studied by researchers at Smithsonian Institution, Natural History Museum, London, and Max Planck Institute for Chemistry. Hotspot tracks tied to plume tail activity are used to reconstruct absolute plate motions in models developed by NOAA, USGS, and Geological Survey of Canada.

Debate, alternative models, and controversies

The plume hypothesis is contested by alternative explanations advanced by scientists at University College London, Open University, University of Leeds, and Monash University who emphasize shallow processes such as edge-driven convection, lithospheric extension, and passive percolation of melts. Critics cite ambiguous seismic imaging, variable geochemical signatures, and the absence of clear thermal anomalies beneath some hotspots, with proponents responding through improved tomography from arrays like USArray and joint inversion studies by GFZ Potsdam. Controversies involve the depth of source regions, role of subduction-derived heterogeneity, and interpretations of plume-induced uplift versus tectonic uplift promoted in papers presented at conferences like the American Geophysical Union and European Geosciences Union meetings. Policy-relevant discussions have occurred within panels at National Academy of Sciences and workshops hosted by International Union of Geodesy and Geophysics.

Implications for plate tectonics and mantle dynamics

If real, plumes imply thermal and chemical coupling between the core and convecting mantle, influencing mantle convection style, heat flux budgets estimated by International Energy Agency-affiliated studies, and the long-term evolution of continental lithosphere such as the East African Rift and Icelandic Rift. Plumes bear on interpretations of mantle mixing, preservation of primordial reservoirs possibly linked to isotope geochemistry results from laboratories at Lawrence Berkeley National Laboratory and Oak Ridge National Laboratory, and the driving forces of continental breakup events recognized in the Gondwana rifting record. Understanding plume dynamics informs natural hazard assessments for intraplate volcanism in regions monitored by agencies like USGS, Geoscience Australia, and Instituto Geográfico Nacional (Spain), and shapes theoretical frameworks taught at universities such as University of Cambridge, Harvard University, and University of Oxford.

Category:Geology