Greenland Plate

The Greenland Plate is a supposed tectonic plate bounded to the west by Nares Strait, a probable transform fault, on the southwest by the Ungava transform underlying Davis Strait, on the southeast by the Mid-Atlantic Ridge,[1] and the northeast by the Gakkel Ridge, with its northwest border is still being explored.[2] The Greenland craton is made up of some of the oldest rocks on Earth. The Isua greenstone belt in southwestern Greenland contains the oldest known rocks on Earth dated at 3.7–3.8 billion years old.[3]

The Precambrian basement of Greenland formed an integral part of the Laurentian Shield that is at the core of the North American continent. Greenland was formed in two rifting stages from the main body of North America. The first, during the Cretaceous period formed Baffin Bay. Baffin Bay is the northwestern extension and terminus of the North Atlantic-Labrador Sea rift system that started forming 140 million years ago in the Early Cretaceous epoch.[4] The Labrador Sea started opening 69 million years ago[5] during the Maastrichtian age but seafloor spreading appears to have ceased by the Oligocene epoch, 30–35 million years ago.[6] Correlations between tectonic units in Canada and Greenland have been proposed,[7] however, the pre-spreading fit of Greenland to Canada is still not accurately known.[8]

Since the closure of the North Atlantic–Labrador Sea rift, Greenland has moved roughly in conjunction with North America; thus, there are questions as to whether the Greenland Plate should be still considered a separate plate at all.[9][10] The area between Greenland and Baffin Island is, however, seismically very active, being the location of the epicenter of many earthquakes including a 7.3-magnitude earthquake in 1933. As of 2009, scientists have been unable to correlate the seismicity with particular geological structures or geophysical anomalies. It has been suggested that seismicity in the region is related to the stresses associated with post-glacial rebound.[11][12]

See also

References

  1. ^ "BAFFIN BAY" (PDF). Indian and Northern Affairs Canada. Archived from the original (PDF) on 2011-06-13. Retrieved 2009-10-04. Cite journal requires |journal= (help)
  2. ^ Denmark hopes to claim North Pole BBC News, 5 October 2004. Accessed 10 November 2006.
  3. ^ Appel, Peter W.U., Hugh R. Rollinson, and Jacques L.R. Touret. (2001) "Remnants of an Early Archaean (>3.75 Ga) sea-floor, hydrothermal system in the Isua Greenstone Belt." Precambrian Research, Vol. 112, Issues 1–2, 15 November, pp. 27–49.
  4. ^ Le Pichon, X., Sibuet, J. C. & Francheteau, J. (1977-03-23). "The fit of the continents around the North Atlantic Ocean". Tectonophysics. 38-3/4: 169–209.CS1 maint: multiple names: authors list (link)
  5. ^ Roest, W.R.; Srivastava, S.P. (1989). "Sea-floor spreading in the Labrador Sea: a new reconstruction". 17. Geology: 1000–1003. doi:10.1130/0091-7613(1989)017<1000:sfsitl>2.3.co;2. Cite journal requires |journal= (help)
  6. ^ J. C. Harrison; U. Mayr; D. H. McNeil; A. R. Sweet; J. J. Eberle; D. J. McIntyre; C. R. Harington; James A. Chalmers; Gregers Dam; Henrik Nohr-Hansen (September 1999). "Correlation of Cenozoic sequences of the Canadian Arctic region and Greenland; implications for the tectonic history of northern North America". 47 (3). Bulletin of Canadian Petroleum Geology: 223–254. Cite journal requires |journal= (help)
  7. ^ Hoffman, P.F. 1989: Precambrian geology and tectonic history ofNorth America. In: Bally, A.W. & Palmer, A.R. (eds): The geology of North America, 447–512. Boulder,Colorado: Geological Society of America.
  8. ^ Niels Henriksen; A.K. Higgins; Feiko Kalsbeek; T. Christopher R. Pulvertaft (2000). "Greenland from Archaean to Quaternary" (PDF) (185). Greenland Survey Bulletin. Retrieved 2009-10-04.
  9. ^ Chadwick, B. & Garde, A.A. 1996: Palaeoproterozoic obliqueplate convergence in South Greenland: a reappraisal of theKetilidian Orogen. In: Brewer, T.S. (ed.): Precambrian crustalevolution in the North Atlantic region. Geological Society Special Publication (London) 112, 179–196}
  10. ^ Peter A. Ziegler (1990) Geological atlas of Western and Central Europe. London. Geological Society. p. 125. ISBN 978-90-6644-125-5
  11. ^ Stein, S., Sleep, N.H., Geller, R.J., Wang, S.-C. & Kroeger, G.C. (1979). "Earthquakes along the passive margin of eastern Canada". 6. Geophys. Res. Lett.: 538–540. doi:10.1029/gl006i007p00537. Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link)
  12. ^ Allison L. Bent (2002-03-18). "The 1933 Ms=7.3 Baffin Bay earthquake: strike-slip faulting along the northeastern Canadian passive margin" (PDF). 150. Geophys. J. Int.: 724–736. doi:10.1046/j.1365-246x.2002.01722.x. Archived from the original (PDF) on 2011-07-21. Cite journal requires |journal= (help)
Aegir Ridge

The Aegir Ridge is an extinct segment of the Mid-Atlantic Ridge in the far-northern Atlantic Ocean. It marks the initial break-up boundary between Greenland and Norway, along which seafloor spreading was initiated at the beginning of the Eocene epoch to form the northern Atlantic Ocean. Towards the end of the Eocene, the newly forming Kolbeinsey Ridge propagated northwards from Iceland, splitting the Jan Mayen Microcontinent away from the Greenland Plate. As the Kolbeinsey Ridge formed, so activity on the Aegir Ridge reduced, ceasing completely at the end of the Oligocene epoch when the Kolbeinsey Ridge reached the Jan Mayen Fracture Zone.The relatively thin crust and short lifespan of the Aegir Ridge is anomalous given its proximity to the Iceland hotspot. Mantle hotspots deliver warm, actively-upwelling material to mid-ocean ridges, increasing mantle melting and crustal production. Likely, the stresses associated with plate tectonics and the mechanical structure of the lithosphere created a situation in which spreading at the Kolbeinsey Ridge was energetically favorable to spreading at the Aegir Ridge. As the Kolbeinsey Ridge began rifting, hotspot material would then draw out of the Aegir Ridge and flow preferentially towards the Kolbeinsey Ridge, leading to the ultimate extinction of the spreading center.

Arctic Alaska

Arctic Alaska or Far North Alaska is a region of the U.S. state of Alaska generally referring to the northern areas on or close to the Arctic Ocean.

It commonly includes North Slope Borough, Northwest Arctic Borough, Nome Census Area, and is sometimes taken to include parts of the Yukon-Koyukuk Census Area. Some notable towns there include Prudhoe Bay, Barrow, Kotzebue, Nome, and Galena.

Most of these communities have no highways and can only be reached by aircraft or snowmobile in good weather. Originally inhabited by various Alaska Native groups living off hunting, whaling, or salmon fishing, modern settlement in Arctic Alaska was driven first by discoveries of gold and later on by the extraction of petroleum.

The ecosystem consists largely of tundra covering mountain ranges and coastal plains which are home to bears, wolves, sheep, muskoxen, caribou, and numerous species of birds, the north coast has been defined as the Arctic coastal tundra ecoregion. Arctic Alaska is also the location of the Arctic National Wildlife Refuge, Gates of the Arctic National Park and Preserve, Kobuk Valley National Park and the National Petroleum Reserve–Alaska. The Arctic experiences midnight sun in the summer and polar night in the winter.

Arctic Circle

The Arctic Circle is one of the two polar circles and the most northerly of the five major circles of latitude as shown on maps of Earth. It marks the northernmost point at which the centre of the noon sun is just visible on the December solstice and the southernmost point at which the centre of the midnight sun is just visible on the June solstice. The region north of this circle is known as the Arctic, and the zone just to the south is called the Northern Temperate Zone.

As seen from the Arctic, the Sun is above the horizon for 24 continuous hours at least once per year (and therefore visible at midnight) and below the horizon for 24 continuous hours at least once per year (and therefore not visible at noon). This is also true in the Antarctic region, south of the equivalent Antarctic Circle.

The position of the Arctic Circle is not fixed and currently runs 66°33′47.8″ north of the Equator. Its latitude depends on the Earth's axial tilt, which fluctuates within a margin of more than 2° over a 41,000-year period, due to tidal forces resulting from the orbit of the Moon. Consequently, the Arctic Circle is currently drifting northwards at a speed of about 15 m (49 ft) per year.

Arctic Climate Impact Assessment

The Arctic Climate Impact Assessment (ACIA) is a study describing the ongoing climate change in the Arctic and its consequences: rising temperatures, loss of sea ice, unprecedented melting of the Greenland ice sheet, and many impacts on ecosystems, animals, and people. The ACIA is the first comprehensively researched, fully referenced, and independently reviewed evaluation of Arctic climate change and its impacts for the region and for the world. The project was guided by the intergovernmental Arctic Council and the non-governmental International Arctic Science Committee. Three hundred scientists participated in the study over a span of three years.

The 140-page synthesis report Impacts of a Warming Arctic was released in November 2004, and the scientific report later in 2005.The ACIA Secretariat is located at the International Arctic Research Center at the University of Alaska Fairbanks.

Arctic oscillation

The Arctic oscillation (AO) or Northern Annular Mode/Northern Hemisphere Annular Mode (NAM) is a weather phenomenon at the Arctic and Antarctic poles north (or south) of 20 degrees latitude. The index varies over time with no particular periodicity, and is characterized by non-seasonal sea-level pressure anomalies of one sign in the Arctic, balanced by anomalies of opposite sign centered at about 37–45N.The North Atlantic oscillation (NAO) is a close relative of the AO. There is debate over whether one or the other is more fundamentally representative of the atmosphere's dynamics. The NAO may be identified in a more physically meaningful way, which may carry more impact on measurable effects of changes in the atmosphere.

British Arctic Territories

The British Arctic territories, now known as the Arctic Archipelago (excepting islands in Hudson Bay, which were part of Rupert's Land) were claimed by the United Kingdom in North America. The region was part of British North America.

The British claim to the area was based on the discoveries of Martin Frobisher (1535–1594) in the 16th century. Britain passed control of the islands to Canada in 1880, by means of an Imperial Order in Council, the Adjacent Territories Order, passed under the Royal Prerogative. After the 1880 transfer Canada gradually incorporated the islands with Rupert's Land into the Northwest Territories. The transfer was necessary over the fear of American interest in the area as part of the Monroe Doctrine.On April 1, 1999, the territory of Nunavut was created from the eastern portion of the Northwest Territories. The majority of the islands became part of Nunavut. Islands split between Nunavut and Northwest Territories include Victoria Island, Melville Island, Mackenzie King Island and Borden Island.

These islands were never part of Rupert's Land (Hudson Bay drainage basin) nor the North-Western Territory (mainland north and west of Rupert's Land), both of whose trade monopolies were managed by the Hudson's Bay Company. Canada had acquired those regions in 1870, creating the new Province of Manitoba and Northwest Territories (which originally included northern Ontario, northern Quebec, the rest of Manitoba, all of Saskatchewan, part of Alberta, part of British Columbia, Yukon, and Nunavut), with the name Northwest Territories retained by the successor government in the region flanked by the Mackenzie River drainage to the north of Alberta.

Circumpolar peoples

Circumpolar peoples and Arctic peoples are umbrella terms for the various indigenous peoples of the Arctic.

Far North (Russia)

The Extreme North or Far North (Russian: Крайний Север, Дальний Север) is a large part of Russia located mainly north of the Arctic Circle and boasting enormous mineral and natural resources. Its total area is about 5,500,000 square kilometres (2,100,000 sq mi), comprising about one-third of Russia's total area. Formally, the regions of the Extreme North comprise the whole of Yakutia, Magadan Oblast, Chukotka Autonomous Okrug, Kamchatka Krai and Murmansk Oblast, as well as certain parts and cities of Arkhangelsk Oblast, Komi Republic, Tyumen Oblast, Krasnoyarsk Krai, Irkutsk Oblast, Sakhalin Oblast, Khabarovsk Krai, as well as all islands of the Arctic Ocean, its seas, the Bering Sea, and the Sea of Okhotsk.

Due to the harsh conditions of the area, people who work there have traditionally been entitled by the Russian government to higher wages than workers of other regions. As a result of the climate and environment, the indigenous peoples of the area have developed certain genetic differences that allow them to better cope with the region's environment, as do their cultures.

Geography of Greenland

Greenland is located between the Arctic Ocean and the North Atlantic Ocean, northeast of Canada and northwest of Iceland. The territory comprises the island of Greenland—the largest island in the world—and more than a hundred other smaller islands (see alphabetic list). As an island, Greenland has no land boundaries and 44,087 km of coastline. A sparse population is confined to small settlements along certain sectors of the coast. Greenland possesses the world's second largest ice sheet.

Greenland sits atop the Greenland plate, a subplate of the North American plate. The Greenland craton is made up of some of the oldest rocks on the face of the earth. The Isua greenstone belt in southwestern Greenland contains the oldest known rocks on Earth, dated at 3.7–3.8 billion years old.The vegetation is generally sparse, with the only patch of forested land being found in Nanortalik Municipality in the extreme south near Cape Farewell.

The climate is arctic to subarctic, with cool summers and cold winters. The terrain is mostly a flat but gradually sloping icecap that covers all land except for a narrow, mountainous, barren, rocky coast. The lowest elevation is sea level and the highest elevation is the summit of Gunnbjørn Fjeld, the highest point in the Arctic at 3,694 meters (12,119 ft). The northernmost point of the island of Greenland is Cape Morris Jesup, discovered by Admiral Robert Peary in 1900. Natural resources include zinc, lead, iron ore, coal, molybdenum, gold, platinum, uranium, hydropower and fish.

Index of Greenland-related articles

The following is an alphabetical list of topics related to the nation of Kalaallit Nunaat (Greenland).

Jan Mayen Microcontinent

The Jan Mayen Microcontinent is a fragment of continental crust within the oceanic part of the western Eurasian Plate lying northeast of Iceland. At the onset of separation between the Greenland and Eurasian plates 55 million years ago, it formed part of the eastern margin of the Greenland Plate. Propagation of a new spreading center from the Reykjanes Ridge separated this microcontinent from the Greenland Plate. For a short period it formed a microplate, until the Aegir Ridge became inactive, after which it formed part of the Eurasian Plate. The island of Jan Mayen is a much younger feature, formed of volcanic rock, built up at the northernmost tip of the microcontinent.

Labrador Sea

The Labrador Sea (French: mer du Labrador, Danish: Labradorhavet) is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffin Bay through the Davis Strait. It has been described as a marginal sea of the Atlantic.The sea formed upon separation of the North American Plate and Greenland Plate that started about 60 million years ago and stopped about 40 million years ago. It contains one of the world's largest turbidity current channel systems, the Northwest Atlantic Mid-Ocean Channel (NAMOC), that runs for thousands of kilometers along the sea bottom toward the Atlantic Ocean.

The Labrador Sea is a major source of the North Atlantic Deep Water, a cold water mass that flows at great depth along the western edge of the North Atlantic, spreading out to form the largest identifiable water mass in the World Ocean.

List of tectonic plates

This is a list of tectonic plates on the Earth's surface. Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). The composition of the two types of crust differs markedly, with mafic basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granitic rocks.

North American Arctic

The North American Arctic comprises the northern portions of Alaska (USA), Northern Canada and Greenland. Major bodies of water include the Arctic Ocean, Hudson Bay, the Gulf of Alaska and North Atlantic Ocean. The western limit is the Seward Peninsula and the Bering Strait. The southern limit is the Arctic Circle latitude of 66° 33’N, which is the approximate limit of the midnight sun and the polar night.

The Arctic region is defined by environmental limits where the average temperature for the warmest month (July) is below 10 °C (50 °F). The northernmost tree line roughly follows the isotherm at the boundary of this region. The area has tundra and polar vegetation.

Northern Canada

Northern Canada, colloquially the North, is the vast northernmost region of Canada variously defined by geography and politics. Politically, the term refers to three territories of Canada: Yukon, Northwest Territories, and Nunavut. Similarly, the Far North (when contrasted to the North) may refer to the Canadian Arctic: the portion of Canada that lies north of the Arctic Circle, east of Alaska and west of Greenland. This area covers about 39% of Canada's total land area, but has less than 1% of Canada's population.

These reckonings somewhat depend on the arbitrary concept of nordicity, a measure of so-called "northernness" that other Arctic territories share. Canada is the northernmost country in the Americas (excluding the neighbouring Danish Arctic territory of Greenland which extends slightly further north) and roughly 80% of its 35 million residents are concentrated along its southern border with the United States.

Northern Sea Route

The Northern Sea Route (Russian: Се́верный морско́й путь, Severnyy morskoy put, shortened to Севморпуть, Sevmorput) is a shipping route officially defined by Russian legislation as lying east of Novaya Zemlya and specifically running along the Russian Arctic coast from the Kara Sea, along Siberia, to the Bering Strait. The entire route lies in Arctic waters and within Russia's exclusive economic zone (EEZ). Parts are free of ice for only two months per year. The overall route on Russia's side of the Arctic between North Cape and the Bering Strait has been called the Northeast Passage, analogous to the Northwest Passage on the Canada side.

While the Northeast Passage includes all the East Arctic seas and connects the Atlantic and Pacific oceans, the Northern Sea Route does not include the Barents Sea, and it therefore does not reach the Atlantic.Melting Arctic ice caps are likely to increase traffic in and the commercial viability of the Northern Sea Route. One study, for instance, projects "remarkable shifts in trade flows between Asia and Europe, diversion of trade within Europe, heavy shipping traffic in the Arctic and a substantial drop in Suez traffic. Projected shifts in trade also imply substantial pressure on an already threatened Arctic ecosystem."

Polar climate

The polar climate regions are characterized by a lack of warm summers. Every month in a polar climate has an average temperature of less than 10 °C (50 °F). Regions with polar climate cover more than 20% of the Earth's area. Most of these regions are far from the equator, and in this case, winter days are extremely short and summer days are extremely long (or lasting for the entirety of each season or longer). A polar climate consists of cool summers and very cold winters, which results in treeless tundra, glaciers, or a permanent or semi-permanent layer of ice.

Selandian

The Selandian is in the geologic timescale an age or stage in the Paleocene. It spans the time between 61.6 and 59.2 Ma. It is preceded by the Danian and followed by the Thanetian. Sometimes the Paleocene is subdivided in subepochs, in which the Selandian forms the "Middle Paleocene".

Tundra

In physical geography, tundra () is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра (tûndra) from the Kildin Sámi word тӯндар (tūndâr) meaning "uplands", "treeless mountain tract". Tundra vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline.

There are three regions and associated types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra.

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