Azores Plateau

Azores Plateau
Name	Azores Plateau
Type	Large igneous province
Location	North Atlantic Ocean
Coordinates	38°N 28°W
Area	~500,000 km²
Elevation	submerged plateau, some seamounts and islands

Azores Plateau is a broad submerged large igneous province in the North Atlantic Ocean associated with the Azores archipelago, forming a bathymetric high between Iberian Peninsula, Greenland, British Isles, Canary Islands, and Mid-Atlantic Ridge. The plateau influences regional North Atlantic Drift, Gulf Stream, Azores High, and North Atlantic climate variability, and hosts diverse marine biodiversity and active submarine volcanism linked to plate-scale volcanotectonic processes. It is central to debates connecting mantle plumes, seafloor spreading, and intraplate magmatism across the Atlantic basin.

Geography and Extent

The plateau underlies the Azores archipelago, extending toward Terceira Rift, Gorringe Bank, Southeast Azores Seamounts, and the Green Seamounts, with an extent that spans parts of the northeastern Atlantic Ocean Basin, abutting the western flank of the Iberian Margin. Bathymetric mapping by institutions such as European Marine Observation and Data Network, NOAA, GEBCO and research programs including IODP and EMODnet has delineated seamount chains, fracture zones, and abyssal plains across the plateau. Major seafloor features include the Terceira Rift, Gloria Fault, Flemish Cap (proximal influences), and the submerged Mid-Atlantic Ridge discontinuities where ridge segmentation meets plateau topography. The plateau’s relief hosts emergent landforms that form the nine principal islands of the archipelago: São Miguel Island, Terceira Island, Pico Island, São Jorge Island, Faial Island, Santa Maria Island, Flores Island, Corvo Island, and Graciosa Island.

Geological Setting and Formation

The Azores Plateau is interpreted within competing frameworks: a long-lived mantle plume model tied to a deep-seated thermal anomaly beneath the Iberian–Iceland–Azores mantle domain; a plate-driven model invoking enhanced melting at lithospheric discontinuities such as the Terceira Rift and transform faults like the Gloria Fault; and hybrid plume–plate interaction hypotheses advanced by research groups at University of Azores, University of Lisbon, University of Oxford, ETH Zurich, and Scripps Institution of Oceanography. Radiometric ages from lava flows, intrusive complexes, and seamount basalts obtained using K–Ar dating, Ar–Ar dating, and isotope systems (Sr–Nd–Pb–He) have been reported by teams from University of Cambridge, University of Hawaii, Utrecht University, and CNRS showing magmatism spanning Neogene to Holocene. Geochemical signatures include enriched mantle components analogous to OIB (ocean island basalt) suites, with trace-element patterns compared against Iceland plume and Canary hotspot records. Tectonostratigraphic work integrates data from multibeam sonar surveys, seismic reflection profiles collected by RRS James Cook, RV Poseidon, RV Knorr, and RV Melville, and dredge sampling campaigns coordinated with International Ocean Discovery Program operations.

Volcanism and Tectonics

Volcanic activity on the plateau ranges from submarine fissure eruptions to subaerial stratovolcano construction on the islands; historic eruptions recorded at Capelinhos (on Faial Island) and seismic crises near Pico Island illustrate ongoing hazard. Tectonic frameworks involve interaction among the North American Plate, Eurasian Plate, and African Plate with accommodation along the Azores Triple Junction and rift domains including the Terceira Rift and the Glória Fault System. Volcanostratigraphy documents shield-building stages, phonolitic dome formation, and mafic to felsic differentiation processes comparable to magmatic evolution observed at Iceland and Hawaii. Monitoring is conducted by agencies such as Azores Seismovolcanic Surveillance Network, Instituto Português do Mar e da Atmosfera, European Seismological Commission, and collaboratives with USGS and INGV researchers, integrating GPS geodesy, InSAR, and bathymetric change detection.

Oceanography and Hydrothermal Activity

The plateau modifies mesoscale circulation, steering features like Azores Current, North Atlantic Current, and mesoscale eddies monitored by Copernicus Marine Service, AVISO Satellite Altimetry, and oceanographic cruises from Woods Hole Oceanographic Institution and Lamont–Doherty Earth Observatory. Hydrographic surveys reveal water-mass interactions between subpolar and subtropical gyres, influencing marine productivity and plankton biogeography studied by teams at Monterey Bay Aquarium Research Institute, Rosenstiel School of Marine and Atmospheric Science, and IMAR. Seamounts and rifted terrains host hydrothermal systems with fluid chemistry and microbial communities sampled by ROV Alvin, ROV Jason, and Nautile expeditions, yielding sulfide deposits, metal-rich precipitates, and chemosynthetic assemblages analogous to those on Mid-Atlantic Ridge vents and Lost City Hydrothermal Field.

Ecology and Biodiversity

The plateau’s islands and seamounts are biodiversity hotspots where endemism and species exchanges occur among Macaronesia elements such as flora and fauna links to Madeira, Canary Islands, and Cape Verde. Marine habitats include coral gardens, sponge aggregations, and cold-water coral reefs studied by NOAA Fisheries, WWF, and academic teams from University of Azores and Universidade dos Açores. Avifauna on emergent islands comprises breeding populations of Cory's shearwater, Monteiro's storm-petrel, and migratory stopovers for Arctic tern and Bulwer's petrel. Terrestrial biota includes laurel forest relics with affinities to Macaronesian laurisilva and vascular plants catalogued in regional herbaria such as Jardim Botânico da Universidade dos Açores. Conservation initiatives are coordinated with Natura 2000, Ramsar Convention, BirdLife International, and Portuguese protected-area authorities addressing invasive species, fisheries pressures, and climate-driven impacts.

Human History and Use

Human engagement spans early exploration, settlement, and strategic use: Portuguese colonization during the Age of Discovery established way stations on islands such as Santa Maria Island and São Miguel Island that became crucial for Carrack voyages and transatlantic routes used by Christopher Columbus-era navigators, later serving as stopovers for Clipper ships and transatlantic aviation routes pioneered by carriers and navies including RAF and US Navy. Contemporary uses include commercial fisheries regulated under Common Fisheries Policy, azorean agriculture (tea estates on São Miguel Island), tourism centered in Ponta Delgada and Horta, and renewable-energy experiments in wind, wave, and geothermal power explored with partners such as European Commission programs and Horizon 2020 consortia. Maritime jurisdiction falls under the Portuguese Exclusive Economic Zone and governance involves regional bodies like the Autonomous Region of the Azores, national ministries, and international law forums including United Nations Convention on the Law of the Sea.

Category:Macaronesia Category:Large igneous provinces Category:North Atlantic Ocean