Ross Embayment

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Map of Antarctica showing outline of Ross Embayment Map of Antarctica showing outline of Ross Embayment.svg
Map of Antarctica showing outline of Ross Embayment

The Ross Embayment is a large region of Antarctica, comprising the Ross Ice Shelf and the Ross Sea, that lies between East and West Antarctica.

Contents

Extent

The continent of Antarctica has two major divisions; West Antarctica in mostly western longitudes and East Antarctica in mostly eastern longitudes. East Antarctica is the larger and has a higher average elevation. Separating the two subcontinents is a lower elevation topographic region occupied by the Ross Ice Shelf and the Ross Sea. This region is referred to as the Ross Embayment. The embayment comprises an area of approximately 1,137,000 square kilometres (439,000 sq mi). It includes the Ross Sea (637,000 square kilometres (246,000 sq mi)) [1] and the Ross Ice Shelf (as of 2013, 500,809 square kilometres (193,363 sq mi)). [2] The name is most commonly used in the scientific literature, [3] [4] [5] at times along with the West Antarctic Rift System, which is of larger extent and has geologic meaning. [6] Because the rift system includes the embayment, the latter is considered to lie in West Antarctica.

The informal use of the name 'Ross Embayment' tends to denote a smaller region than the rift system. The embayment extends from Northern Victoria Land and the Transantarctic Mountains on the west (in East Antarctica) to the Edward VII Peninsula, Shirase Coast, and Siple Coast on the east (Marie Byrd Land in West Antarctica), and south to the grounding line of the Ross Ice Shelf. [1]

Formation

A view of the Ross Ice Shelf and Ross Sea in Antarctica from the Moderate Resolution Imaging Spectroradiometer (MODIS). North at top. A giant iceberg on the left (west) has broken off the front of the Ross Ice Shelf. The Transantarctic Mountains cross the image from left to lower right. Original file from Commons was image-enhanced. Ross Ice Shelf PS.jpg
A view of the Ross Ice Shelf and Ross Sea in Antarctica from the Moderate Resolution Imaging Spectroradiometer (MODIS). North at top. A giant iceberg on the left (west) has broken off the front of the Ross Ice Shelf. The Transantarctic Mountains cross the image from left to lower right. Original file from Commons was image-enhanced.

The low elevation marine characteristic of the Ross Embayment formed since the Jurassic period. [7] Before that time and earlier East and West Antarctica had similar elevations and the Ross Embayment did not exist. [7] [8] [9] The breakup of the eastern sector of Gondwana in Cretaceous time resulted in crustal extension, thinning and subsidence to form the Ross Embayment. [10] The mechanism of crustal stretching and subsidence in the Ross Embayment has been attributed to detachment faulting. [11] Extension between East and West Antarctica totals about 500 kilometers. [12] Half of this occurred prior to sea floor spreading that separated the New Zealand microcontinents (Zealandia) from Antarctica beginning at 85 million years. [13] The remaining extension occurred in the Central Trough, Northern Basin, and Victoria Land Basin in the western Ross Sea before late Miocene time. [12] [14] Subsidence continued as mantle under the Ross Embayment cooled. [12]

See also

Related Research Articles

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The geography of Antarctica is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth's southern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. It is washed by the Southern Ocean or, depending on definition, the southern Pacific, Atlantic, and Indian Oceans. It has an area of more than 14.2 million km2. Antarctica is the largest ice desert in the world.

<span class="mw-page-title-main">Ross Sea</span> Deep bay of the Southern Ocean in Antarctica

The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who visited this area in 1841. To the west of the sea lies Ross Island and Victoria Land, to the east Roosevelt Island and Edward VII Peninsula in Marie Byrd Land, while the southernmost part is covered by the Ross Ice Shelf, and is about 200 miles (320 km) from the South Pole. Its boundaries and area have been defined by the New Zealand National Institute of Water and Atmospheric Research as having an area of 637,000 square kilometres (246,000 sq mi).

<span class="mw-page-title-main">Weddell Sea</span> Part of the Southern Ocean between Coats Land and the Antarctic Peninsula

The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Martha Coast, Queen Maud Land. To the east of Cape Norvegia is the King Haakon VII Sea. Much of the southern part of the sea is covered by a permanent, massive ice shelf field, the Filchner-Ronne Ice Shelf.

<span class="mw-page-title-main">Antarctic Plate</span> Major tectonic plate containing Antarctica and the surrounding ocean floor

The Antarctic Plate is a tectonic plate containing the continent of Antarctica, the Kerguelen Plateau, and some remote islands in the Southern Ocean and other surrounding oceans. After breakup from Gondwana, the Antarctic plate began moving the continent of Antarctica south to its present isolated location, causing the continent to develop a much colder climate. The Antarctic Plate is bounded almost entirely by extensional mid-ocean ridge systems. The adjoining plates are the Nazca Plate, the South American Plate, the African Plate, the Somali Plate, the Indo-Australian Plate, the Pacific Plate, and, across a transform boundary, the Scotia Plate.

<span class="mw-page-title-main">Amundsen Sea</span> Arm of the Southern Ocean

The Amundsen Sea is an arm of the Southern Ocean off Marie Byrd Land in western Antarctica. It lies between Cape Flying Fish to the east and Cape Dart on Siple Island to the west. Cape Flying Fish marks the boundary between the Amundsen Sea and the Bellingshausen Sea. West of Cape Dart there is no named marginal sea of the Southern Ocean between the Amundsen and Ross Seas. The Norwegian expedition of 1928–1929 under Captain Nils Larsen named the body of water for the Norwegian polar explorer Roald Amundsen while exploring this area in February 1929.

<span class="mw-page-title-main">Transantarctic Mountains</span> Mountain range in Antarctica

The Transantarctic Mountains comprise a mountain range of uplifted rock in Antarctica which extends, with some interruptions, across the continent from Cape Adare in northern Victoria Land to Coats Land. These mountains divide East Antarctica and West Antarctica. They include a number of separately named mountain groups, which are often again subdivided into smaller ranges.

<span class="mw-page-title-main">Marie Byrd Land</span> Unclaimed West Antarctic region

Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of 1,610,000 km2 (620,000 sq mi), it is the largest unclaimed territory on Earth. It was named after the wife of American naval officer Richard E. Byrd, who explored the region in the early 20th century.

<span class="mw-page-title-main">West Antarctica</span> Part of Antarctica that lies within the Western Hemisphere

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The Nordenskjöld Coast is located on the Antarctic Peninsula, more specifically Graham Land, which is the top region of the Peninsula. The Peninsula is a thin, long ice sheet with an Alpine-style mountain chain. The coast consists of 15m tall ice cliffs with ice shelves.

<span class="mw-page-title-main">West Antarctic Rift System</span> Series of rift valleys between East and West Antarctica

The West Antarctic Rift System is a series of rift valleys between East and West Antarctica. It encompasses the Ross Embayment, the Ross Sea, the area under the Ross Ice Shelf and a part of Marie Byrd Land in West Antarctica, reaching to the base of the Antarctic Peninsula. It has an estimated length of 3,000 km (1,900 mi) and a width of approximately 700 km (430 mi). Its evolution is due to lithospheric thinning of an area of Antarctica that resulted in the demarcation of East and West Antarctica. The scale and evolution of the rift system has been compared to that of the Basin and Range Province of the Western United States.

<span class="mw-page-title-main">Geology of Antarctica</span> Geologic composition of Antarctica

The geology of Antarctica covers the geological development of the continent through the Archean, Proterozoic and Phanerozoic eons.

The Erebus hotspot is a volcanic hotspot responsible for the high volcanic activity on Ross Island in the western Ross Sea of Antarctica. Its current eruptive zone, Mount Erebus, has erupted continuously since its discovery in 1841. Magmas of the Erebus hotspot are similar to those erupted from hotspots at the active East African Rift in eastern Africa. Mount Bird at the northernmost end of Ross Island and Mount Terror at its eastern end are large basaltic shield volcanoes that have been potassium-argon dated 3.8–4.8 and 0.8–1.8 million years old.

<span class="mw-page-title-main">East Antarctic Shield</span> Cratonic rock body which makes up most of the continent Antarctica

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<span class="mw-page-title-main">Adare Basin</span>

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