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| Afro-Arabian mantle plume | |
|---|---|
| Name | Afro-Arabian mantle plume |
| Type | Mantle plume hypothesis |
| Location | Horn of Africa, Red Sea, Gulf of Aden, Arabian Peninsula |
| Discovered | 1970s–1990s studies |
| Geology | mantle plume, hotspot volcanism, rift tectonics |
Afro-Arabian mantle plume
The Afro-Arabian mantle plume is a proposed deep-mantle upwelling invoked to explain widespread East African Rift volcanism, Afar Depression uplift, and magmatism beneath the Horn of Africa and adjacent Arabian Peninsula. Advocates link it to anomalous seismic tomography low-velocity zones, large helium isotope ratios, and the distribution of flood basalts and shield volcanoes across Ethiopia, Djibouti, Somalia, Yemen, and Saudi Arabia. The hypothesis interfaces with debates involving plate tectonics, mantle convection, and the dynamics of continental breakup.
The concept describes a buoyant, thermochemical plume rising from deep within the mantle beneath northeast Africa and parts of Arabia, driving elevated heat flow, regional uplift of the Afar Triple Junction, and generating magmatism observed in the Ethiopian Plateau, Red Sea Rift, and Gulf of Aden margins. It is often compared to canonical plume models proposed for Hawaii and Iceland but applied to continental rifting contexts like the East African Rift System. Key proponents include researchers associated with institutions such as the British Geological Survey, Smithsonian Institution, and Max Planck Institute for Chemistry who have integrated seismic, geochemical, and geodynamic datasets.
The proposed plume lies at the intersection of major tectonic features: the Red Sea Rift, the Gulf of Aden Rift, and the East African Rift, near the Afar Triple Junction where the Somali Plate, Nubian Plate, and Arabian Plate meet. Regional geology records Cenozoic flood basalts including the Ethiopian Traps contemporaneous with the opening of the Red Sea and Gulf of Aden and correlated with breakup episodes between the African Plate and Arabian Plate. The Afro-Arabian region is spatially linked to hotspot-like tracks suggested for portions of the Arabian Shield and offshore provinces adjacent to the Socotra region.
Seismic studies using networks such as the International Seismological Centre and experiments by groups from Columbia University, ETH Zurich, and Utrecht University have imaged low-velocity anomalies beneath the Ethiopian Plateau and beneath parts of Arabia, interpreted as hot, potentially plume-related material. Gravity and geoid anomalies noted by researchers at NASA and GFZ Potsdam provide complementary signals of mantle upwelling. Geochemical data—high 3He/4He ratios sampled from sources like Dabbahu Caldera, Erta Ale, and Harrat Rahat—have been cited by teams at the US Geological Survey and University of Oxford as indicative of deep, primordial mantle signatures similar to those invoked for Réunion and Tristan da Cunha. Isotopic systems including Sr-Nd-Pb-Hf have been used by investigators from Université de Paris and University of Toronto to trace mantle components and lithospheric contamination.
Surface manifestations associated with the plume hypothesis include the Ethiopian Plateau flood basalts, active silicic and mafic volcanism of the Afar Depression, persistent lava lakes at Erta Ale, and Holocene activity in Yemen and Saudi Arabia such as the Harrat Khaybar and Harrat Rahat volcanic fields. Large igneous province formation, emplacement of traps and rift-related dike swarms observed by teams from Caltech and University of Cambridge have been mapped across southwestern Arabia and northeastern Africa. Remote sensing by Landsat, MODIS, and ASTER has helped document eruptive histories used by volcanologists at IAVCEI and regional geological surveys.
Proponents argue the plume facilitated continental breakup by thermally weakening the lithosphere, promoting rift propagation from the Afar Triple Junction into the East African Rift System and assisting seafloor spreading initiation in the Red Sea and Gulf of Aden. Numerical models developed by groups at MIT, Imperial College London, and Tübingen University simulate plume-lithosphere interaction producing uplift, volcanism, and crustal thinning consistent with geological observations such as extension rates measured by GPS networks operated by UNAVCO and Afghanistan Geodesy Project-affiliated initiatives. The hypothesis links to paleoenvironmental consequences studied by paleoceanographers at WHOI and paleoclimatologists at University of Cambridge through alteration of drainage patterns and sediment fluxes to the Indian Ocean.
Radiometric ages including K-Ar and Ar-Ar determinations from lava sequences across Ethiopia, Djibouti, Yemen, and Oman—published by teams from Harvard University and University of Texas at Austin—indicate pulse-like magmatism beginning in the Oligocene and continuing through the Neogene to recent Holocene eruptions. Correlations with the emplacement of the Afro-Arabian flood basalts and synchronous rift events have been proposed by stratigraphers and geochronologists at Birkbeck, University of London and Monash University. Thermochronology and sedimentary basin analyses by researchers at CSIC and CNRS further constrain uplift and denudation histories associated with plume arrival.
Critics from institutions like University of Oslo, Australian National University, and University of Leeds emphasize alternative explanations: passive rifting driven by far-field stresses from Indian Plate motions, small-scale mantle convection, lithospheric delamination, or melt migration unrelated to a single deep plume. Seismic tomography ambiguity and variable isotopic signatures have led groups at University of Tokyo and Scripps Institution of Oceanography to propose multi-source, shallow-sourced upwellings or edge-driven convection models. Debates continue in forums of AGU, EGU, and publications in journals associated with Nature Publishing Group and The Geological Society of London regarding plume versus plate-driven mechanisms.
Category:Geology of Africa Category:Geology of Asia