The Amerasia Basin, or Amerasian Basin, is one of the two major basins from which the Arctic Ocean can be subdivided (the other one being the Eurasian Basin). The triangular-shaped Amerasia Basin broadly extends from the Canadian Arctic Islands to the East Siberian Sea, and from Alaska to the Lomonosov Ridge. The basin can be further subdivided based on bathymetric features; these include the Canada Basin, the Makarov Basin, the Podvodnikov Basin, the Alpha-Mendeleev Ridge, and the Chukchi Plateau.
The Amerasia Basin is connected to the Pacific Ocean via the Bering Strait and to the North Atlantic Ocean via the Eurasia Basin and the Fram Strait. The continental shelf around the Amerasia Basin is very broad, averaging up to 342 mi (550 km) in width. The average depth of the Amerasia Basin is 12,960 ft (3,950 m), [1] and it covers 2,500,000 km2 (970,000 sq mi). [2]
The Canada Basin (with a maximum depth of 4,000 m (13,000 ft)) is underlain by oceanic crust at its centre, as well as extended continental crust and transitional-type crust around its margins. [3] The Makarov and Podvodnikov basins, may include oceanic crust, though have also been suggested to be highly extended continental crust or intruded by volcanics. The Alpha and Mendeleev ridges (also collectively referred to as the Alpha-Mendeleev Ridge) are considered to be predominantly volcanic in origin, possibly with a component of extended continental crust underneath. The Chukchi Plateau is made of continental crust. [4]
Many scenarios have been proposed for the opening of the Amerasia Basin. The most popular, the "windshield wiper" model, proposes that the Arctic Alaska-Chukotka terrane (AAC) was rotated in a counter-clockwise motion, away from the Canadian Arctic Islands during the Late Jurassic–Cretaceous in one or several stages. [5] Its opening was at the expense of an extinct ocean called the South Anuyi Ocean. It is possible that the windshield model can explain the opening of the Canada Basin, but that a more complex pattern of events is required to explain the structure of the Amerasia Basin as a whole. [6]
The Alpha–Mendeleev Ridge forms part of the Cretaceous High Arctic Large Igneous Province (HALIP) which includes volcanic features offshore and onshore around the Arctic. An associated Early Cretaceous dyke swarm covering at least 350 km × 800 km (220 mi × 500 mi) has also been discovered. [2] HALIP formation is related to the arrival of a mantle plume, possibly centered on the southern end of the Alpha Ridge. The plume arrival may have resulted in a regional plate reorganization event, including the opening of the Amerasia Basin and the rotation of the AAC.
Seafloor spreading or Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean, was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During the Paleozoic–Mesozoic transition c. 250 Ma it occupied almost 70% of Earth's surface. Its ocean floor has completely disappeared because of the continuous subduction along the continental margins on its circumference. Panthalassa is also referred to as the Paleo-Pacific or Proto-Pacific because the Pacific Ocean is a direct continuation of Panthalassa.
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million km2 (40 million sq mi), it is the largest tectonic plate.
Arctica or Arctida was an ancient continent which formed approximately 2.565 billion years ago in the Neoarchean era. It was made of Archaean cratons, including the Siberian Craton, with its Anabar/Aldan shields in Siberia, and the Slave, Wyoming, Superior, and North Atlantic cratons in North America. Arctica was named by Rogers 1996 because the Arctic Ocean formed by the separation of the North American and Siberian cratons. Russian geologists writing in English call the continent "Arctida" since it was given that name in 1987, alternatively the Hyperborean craton, in reference to the hyperboreans in Greek mythology.
In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, most of the ocean basins are large geologic basins that are below sea level.
The Early Cretaceous or the Lower Cretaceous is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
The Lomonosov Ridge is an unusual underwater ridge of continental crust in the Arctic Ocean. It spans 1,800 kilometres (1,100 mi) between the New Siberian Islands over the central part of the ocean to Ellesmere Island of the Canadian Arctic Archipelago. The ridge divides the Arctic Basin into the Eurasian Basin and the Amerasian Basin. The width of the Lomonosov Ridge varies from 60 to 200 kilometres. It rises 3,300 to 3,700 metres above the 4,200-metre (13,800 ft) deep seabed. The minimum depth of the ocean above the ridge is less than 400 metres (1,300 ft). Slopes of the ridge are relatively steep, broken up by canyons, and covered with layers of silt. It is an aseismic ridge.
The Alpha Ridge is a major volcanic ridge under the Arctic Ocean between the Canada Basin and the Lomonosov Ridge. It was active during the formation of the Amerasian Basin. It was discovered in 1963. The highest elevation is about 2,700 m over the ocean floor. It is 200 to 450 km wide. The Alpha Ridge, Lomonosov Ridge, and Nansen-Gakkel Ridge are the three major ranges that divide the Arctic Ocean floor, running generally parallel to each other.
The continental shelf of Russia is a continental shelf adjacent to the Russian Federation. Geologically, the extent of the shelf is defined as the entirety of the continental shelves adjacent to Russia's coast. In international law, however, the United Nations Convention on the Law of the Sea more narrowly defines the extent of the shelf as the seabed and subsoil of the submarine areas over which a state exercises sovereign rights.
The Strand Fiord Formation is a Late Cretaceous volcanic component, located on northwestern and west-central Axel Heiberg Island, Nunavut, Canada. The formation contains flood basalts which are found on western Axel Heiberg Island at Dragon Cliff 300 m (980 ft) tall.
The High Arctic Large Igneous Province (HALIP) is a Cretaceous large igneous province in the Arctic. The region is divided into several smaller magmatic provinces. Svalbard, Franz Josef Land, Sverdrup Basin, Amerasian Basin, and northern Greenland are some of the larger divisions. Today, HALIP covers an area greater than 1,000,000 km2 (390,000 sq mi), making it one of the largest and most intense magmatic complexes on the planet. However, eroded volcanic sediments in sedimentary strata in Svalbard and Franz Josef Land suggest that an extremely large portion of HALIP volcanics have already been eroded away.
The Southwest Indian Ridge (SWIR) is a mid-ocean ridge located along the floors of the south-west Indian Ocean and south-east Atlantic Ocean. A divergent tectonic plate boundary separating the Somali Plate to the north from the Antarctic Plate to the south, the SWIR is characterised by ultra-slow spreading rates (only exceeding those of the Gakkel Ridge in the Arctic) combined with a fast lengthening of its axis between the two flanking triple junctions, Rodrigues (20°30′S70°00′E) in the Indian Ocean and Bouvet (54°17′S1°5′W) in the Atlantic Ocean.
The North Atlantic Igneous Province (NAIP) is a large igneous province in the North Atlantic, centered on Iceland. In the Paleogene, the province formed the Thulean Plateau, a large basaltic lava plain, which extended over at least 1.3 million km2 (500 thousand sq mi) in area and 6.6 million km3 (1.6 million cu mi) in volume. The plateau was broken up during the opening of the North Atlantic Ocean leaving remnants preserved in north Ireland, west Scotland, the Faroe Islands, northwest Iceland, east Greenland, western Norway and many of the islands located in the north eastern portion of the North Atlantic Ocean. The igneous province is the origin of the Giant's Causeway and Fingal's Cave. The province is also known as Brito–Arctic province and the portion of the province in the British Isles is also called the British Tertiary Volcanic Province or British Tertiary Igneous Province.
The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately 14,060,000 km2 (5,430,000 sq mi) and is known as one of the coldest of oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea. It has also been described as an estuary of the Atlantic Ocean. It is also seen as the northernmost part of the all-encompassing World Ocean.
The Shatsky Rise is Earth's third largest oceanic plateau, located in the north-west Pacific Ocean 1,500 km (930 mi) east of Japan. It is one of a series of Pacific Cretaceous large igneous provinces (LIPs) together with Hess Rise, Magellan Rise, and Ontong Java-Manihiki-Hikurangi. It was named for Nikolay Shatsky (1895-1960), a Soviet geologist, expert in tectonics of ancient platforms.
The Chukchi Plateau or Chukchi Cap is a large subsea formation extending north from the Alaskan margin into the Arctic Ocean. The ridge is normally covered by ice year-round, and reaches an approximate bathymetric prominence of 3,400 m with its highest point at 246 m below sea level. As a subsea ridge extending from the continental shelf of the United States north of Alaska, the Chukchi Plateau is an important feature in maritime law of the Arctic Ocean and has been the subject of significant geographic research. The ridge has been extensively mapped by the USCGC Healy, and by the Canadian icebreaker CCGS Louis S. St-Laurent in 2011 and RV Marcus Langseth, a National Science Foundation vessel operated by the Lamont–Doherty Earth Observatory of Columbia University.
The Arctic Alaska-Chukotka terrane (AAC) is a microcontinent that today encompasses the North Slope, Brooks Range, and Seward Peninsula of northern Alaska; the Chukotka Peninsula, New Siberia Islands, and Wrangel Island in eastern Siberia; and the continental shelves of the Bering, Beaufort, and Chukchi seas. Comparable in size to Greenland, the AAC is the largest of the Neoproterozoic–early Paleozoic continental fragments now dispersed around the Arctic Ocean; some of which possibly formed the continent Arctida.
The Canadian Arctic Rift System is a major North American geological structure extending from the Labrador Sea in the southeast through Davis Strait, Baffin Bay and the Arctic Archipelago in the northwest. It consists of a series of interconnected rifts that formed during the Paleozoic, Mesozoic and Cenozoic eras. Extensional stresses along the entire length of the rift system have resulted in a variety of tectonic features, including grabens, half-grabens, basins and faults.