Atlantic Plate

Atlantic Plate
Name	Atlantic Plate
Type	Tectonic plate
Area km2	106000000
Move direction	Northwest–southeast
Move speed cm per year	2–4
Neighbours	North American Plate; South American Plate; African Plate; Eurasian Plate; Antarctic Plate; Caribbean Plate; Scotia Plate; Cocos Plate

Atlantic Plate The Atlantic Plate is a hypothetical large oceanic tectonic unit used in some geodynamic syntheses to describe plate interactions in the Atlantic basin. It occupies much of the central and southern Atlantic Ocean between the continental margins of North America, South America, Africa, Europe, and Antarctica. The concept is invoked in comparative studies alongside the Pacific Plate, Nazca Plate, Indian Plate, and Eurasian Plate to explain mid-ocean ridge dynamics, transform faulting, and the distribution of oceanic lithosphere.

Overview

The Atlantic Plate concept synthesizes observations from the Mid-Atlantic Ridge, Gulf of Mexico margins, Agulhas Current outflow regions, and the Antarctic-adjacent basins to frame a coherent plate-scale model. Researchers from institutions such as the US Geological Survey, British Geological Survey, Scripps Institution of Oceanography, and National Oceanography Centre use bathymetry from missions like TOPEX/Poseidon, Jason-1, Challenger Deep surveys and seismic profiles from expeditions including RV Knorr and RV Polarstern. Comparative work references major events such as the Breakup of Pangaea, the Opening of the South Atlantic, the Opening of the North Atlantic, and episodes recorded in the Geological Time Scale.

Geology and Structure

Models describe the plate as primarily oceanic crust formed at the Mid-Atlantic Ridge with thickened crust near passive margins like the Brazilian Highlands and the West African Craton. Structural studies incorporate data from the ODP Leg 154 and IODP Expedition programs, gravity anomalies measured by GRACE and magnetic anomaly stripes correlated with the Geomagnetic Polarity Time Scale. Lithospheric thickness estimates use heat flow compilations from the International Heat Flow Commission and mantle tomography informed by Global Seismographic Network datasets. Continental breakup processes cite analogs in the North Sea Basin, the Gulf of Aden, and the Tasman Sea.

Plate Boundaries and Interactions

Along its margins the plate interacts with the North American Plate along the Mid-Atlantic Ridge spreading center, with the Eurasian Plate across the Reykjanes system linked to the Iceland hotspot and the Laki eruption record. Southward interactions with the South American Plate and African Plate reflect transform faults such as the Romanche Fracture Zone and Vema Fracture Zone. The southern boundary adjacent to the Antarctic Plate involves complex ridge segmentation near the Bouvet Triple Junction. Microplate interactions reference the Scotia Plate and the Caribbean Plate along the South Sandwich Islands arc and the Lesser Antilles.

Tectonic History and Evolution

Evolutionary scenarios link the plate-scale development to the rifting of Rodinia and later to the Breakup of Pangaea, driven by mantle plume events like the Sierra Leone Ridge and inferred plume activity related to the Saint Helena hotspot and the Cameroon Volcanic Line. Chronologies use seafloor spreading rates derived from classic studies by Fred Bullard, Walter Pitman, and Drummond Matthews, and integrate paleogeographic reconstructions from teams at the Paleomap Project and the University of Utrecht laboratories. Major tectonic reorganizations coincide with oceanic plate reorganizations documented during the Cretaceous Normal Superchron and the Paleocene–Eocene Thermal Maximum.

Seismicity and Volcanism

Seismicity along mid-ocean ridges and transform faults is cataloged by the International Seismological Centre and satellite altimetry missions. Notable volcanic expressions are observed at Iceland, the Azores archipelago, the Ascension Island and St. Helena volcanic provinces, and submarine volcanoes such as Kick-'em-Jenny analogs. Hydrothermal circulation along ridge crests supports studies of chemosynthetic ecosystems explored by Deepsea Challenger and Alvin dives. Volcanic hazards research connects to historic eruptions recorded in the Holocene and monitoring by observatories like Icelandic Meteorological Office and Instituto Português do Mar e da Atmosfera.

Oceanic Features and Topography

Key features include the Mid-Atlantic Ridge axial valley, large transform offsets like the Charlie-Gibbs Fracture Zone, abyssal plains near the Brazil Basin, and seamount chains including the Broken Ridge and Walvis Ridge. Sediment deposition patterns reference the Amazon Fan, the Niger Delta, and Antarctic-influenced drifts near the Weddell Sea Abyssal Plain. Ocean circulation interacts with topography through currents such as the Gulf Stream, North Atlantic Drift, Brazil Current, and Benguela Current, influencing biogeographic provinces studied by institutions like the Monterey Bay Aquarium Research Institute.

Human and Environmental Impacts

Economic and environmental implications involve seabed mineral exploration regulated under the United Nations Convention on the Law of the Sea and mapped by agencies including the International Seabed Authority and national bodies like NOAA and ANP Brazil. Fisheries in regions influenced by plate-controlled upwelling affect communities in Iceland, Mauritania, Brazil, and Portugal and are studied by the Food and Agriculture Organization. Climate records obtained from Atlantic sediments inform analyses of the Little Ice Age, the Younger Dryas, and modern climate change reports by the Intergovernmental Panel on Climate Change. Marine biodiversity hotspots along ridge and seamount systems are subjects of conservation efforts by organizations such as IUCN and Oceana.

Category:Tectonics