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| Southeast Azores Seamounts | |
|---|---|
| Name | Southeast Azores Seamounts |
| Location | Atlantic Ocean, southeast of Azores |
| Country | Portugal |
| Depth | variable |
| Type | Seamount chain |
Southeast Azores Seamounts are a chain of submarine volcanic edifices located in the North Atlantic Ocean southeast of the Azores archipelago and east of the Mid-Atlantic Ridge. The seamounts form a linear to clustered group aligned with regional tectonic features near the boundary between the Eurasian Plate and the African Plate and lie within the exclusive economic zone of Portugal. They are noted for complex bathymetry, episodic volcanism, hydrothermal activity, and diverse benthic communities that attract international scientific expeditions from institutions such as the Portuguese Institute for the Sea and Atmosphere and the National Oceanography Centre (United Kingdom).
The chain extends across abyssal plains south of São Miguel Island and southeast of Santa Maria Island with individual summits rising from depths greater than 3,000 m to crest depths of a few hundred meters above the seafloor. Bathymetric mapping by research vessels from the NOAA and the European Marine Observation and Data Network reveals seamount shapes including conical volcanoes, guyots, erosional terraces, and elongated ridges influenced by faults associated with the Glória Fault system and diffuse deformation of the Azores Triple Junction. Sediment drifts and contourite deposits alongside the edifices record interactions with the Gulf Stream extension, the North Atlantic Current, and episodic turbidity currents similar to events documented near the Azores Plateau and the Iberian Margin.
The origin of the chain is debated among scholars who compare hotspot-related models such as the Iceland hotspot hypothesis with lithospheric extension and propagating rift models tied to the Mid-Atlantic Ridge and the Terceira Rift. Petrological analyses show alkaline to transitional basalts with nepheline- and olivine-bearing lithologies akin to products from Furnas and Sete Cidades volcanic centers on São Miguel and São Jorge Island. Radiometric dating using techniques employed by teams from the Max Planck Institute for Chemistry and the University of Lisbon indicate Pleistocene to Holocene ages for some edifices, with geophysical evidence from seismic reflection profiles and multibeam surveys revealing intrusive sills, dike swarms, and caldera-like collapse structures reminiscent of formations at Capelinhos on Faial Island.
Hydrographic surveys indicate that seamount-induced upwelling and internal waves modify water masses comparable to observed effects at the Great Meteor Seamount and the Gorringe Bank. Measured temperature anomalies, methane plumes, and chemosynthetic signatures detected by autonomous vehicles and submersibles operated by Woods Hole Oceanographic Institution and the Monterey Bay Aquarium Research Institute suggest diffuse and focused hydrothermal discharge, with mineral precipitates similar to those at the Lost City Hydrothermal Field and the Lucky Strike vent field. Acoustic and CTD casts reveal interactions with oxygen minimum layers studied by teams from the Scripps Institution of Oceanography and episodic plankton blooms documented by satellites from Copernicus Programme and instruments aboard NOAA platforms.
The seamount chain hosts diverse benthic and pelagic assemblages including cold-water corals, sponges, and endemic crustaceans with similarities to faunas described from the Azores Marine Park and the Madeira seamounts. Deep-sea fish such as members of the genera Loligo-related taxa, Aphyonidae relatives, and mesopelagic species recorded by trawls and ROV surveys conducted by the CIBRA consortium show assemblage structures influenced by substrate heterogeneity and hydrothermal habitats analogous to those at Menez Gwen. Macrofaunal communities sustain higher trophic levels including migratory cetaceans observed by researchers from the Bermuda Institute of Ocean Sciences and commercially important demersal fishes exploited in fisheries regulated by the European Commission and the International Council for the Exploration of the Sea.
Exploration has involved multinational campaigns using research vessels such as the RV Atlantis (AGOR-25), the RV Belgica (A962), and the RV L'Atalante, deploying ROVs, AUVs, and HOVs from institutions including the European Marine Biological Resource Centre and the National Museum of Natural History, France. Scientific objectives have spanned bathymetric mapping, geochemical sampling, biodiversity inventories, and hazard assessment related to submarine volcanism and tsunamigenic potential comparable to historical events affecting Terceira and the Azores Islands. Commercial interests include exploratory mineral assessments paralleling investigations at the Mid-Atlantic Ridge and regulatory dialogues involving the International Seabed Authority and the Portuguese Directorate-General for Natural Resources, Safety and Maritime Services.
The seamounts fall under maritime jurisdiction influenced by United Nations Convention on the Law of the Sea frameworks and Portuguese national regulations for offshore activities, with conservation measures informed by precedents such as the designation of the Azores Marine Park and Natura 2000 sites around the Azores. Ongoing proposals from academic consortia and non-governmental organizations including the World Wildlife Fund and IUCN aim to balance scientific research, sustainable fisheries management overseen by the European Commission and the International Council for the Exploration of the Sea, and potential protections similar to those enacted for other North Atlantic seamounts.
Category:Seamounts of the Atlantic Ocean Category:Geology of Portugal Category:Marine biodiversity