The Flemish Cap is an area of shallow waters in the north Atlantic Ocean centered roughly at 47° north, 45° west or about 563 km (350 miles) east of St. John's, Newfoundland and Labrador .
17-528: The shallow water is caused by a wide underwater plateau covering an extended area of 42,000 km (12,000 square miles). Depths at the cap range from approximately 122 m (400 feet) to 700 m (2,300 feet). The Flemish Cap is located within an area of transition between the cold waters of the Labrador Current and warmer waters influenced by the Gulf Stream . The mixing of the warmer and colder waters over
34-413: A tectonic plate via subduction , the process by which one plate is forced under the other when two plates collide. The plate which is being forced down, the subducted plate, is pushed against the upper, over-riding plate. Sediment on the ocean floor of the subducting plate is often scraped off as the plate descends. This accumulated material is called an accretionary wedge (or accretionary prism), which
51-427: A consequence, they tend to "dock" to continental margins and be preserved as accreted terranes . Such terranes are often better preserved than the exposed parts of continental flood basalts and are therefore a better record of large-scale volcanic eruptions throughout Earth's history. This "docking" also means that oceanic plateaus are important contributors to the growth of continental crust. Their formations often had
68-619: A dramatic impact on global climate, such as the most recent plateaus formed, the three, large, Cretaceous oceanic plateaus in the Pacific and Indian Ocean: Ontong Java, Kerguelen, and Caribbean. Geologists believe that igneous oceanic plateaus may well represent a stage in the development of continental crust as they are generally less dense than oceanic crust while still being denser than normal continental crust. Density differences in crustal material largely arise from different ratios of various elements, especially silicon . Continental crust has
85-580: A higher density than the rocks making up the majority of continental crust. Island arcs and other volcanic rocks are also lower in density than the oceanic crust, and are therefore not easily subducted along with the oceanic crust that surrounds them. Instead, these less-dense bits of crust will collide with existing continental crust on the upper plate once the oceanic crust separating them is completely subducted. Most continents are composed of multiple accreted " terranes ", pieces of low-density continental crust with different origins. For example, North America
102-793: Is made up of multiple accreted terranes that collided with the Laurentian proto-continent , such as the Proterozoic Yavapai , Mazatzal , and Grenville Province Terranes. Accreted terranes along modern subduction plate boundaries include the Nankai accretionary complex of Japan (subduction of the Philippine Plate beneath the Eurasian Plate ), the Barbados Ridge in the Caribbean (subduction of
119-402: Is pushed against and attaches to the upper plate. In addition to accumulated ocean sediments, volcanic island arcs or seamounts present on the subducting plate may be amalgamated onto existing continental crust on the upper plate, increasing the continental landmass. Continental crust differs significantly from oceanic crust. Oceanic crust is primarily composed of basaltic rocks, which have
136-431: Is therefore in international fishing waters. Overfishing became a serious issue in the latter 20th & early 21st centuries. Cod are particularly threatened here, as are American plaice , and the numbers of redfish have shown such significant decline as to be classified endangered. During the last decade of the 20th century & the beginning part of the 21st century, Canada made an effort to prevent overfishing in
153-417: Is yet more felsic, and so on through geologic time. Accretion (geology) In geology , accretion is a process by which material is added to a tectonic plate at a subduction zone , frequently on the edge of existing continental landmasses . The added material may be sediment, volcanic arcs , seamounts , oceanic crust or other igneous features. Accretion involves the addition of material to
170-633: The Caribbean , Ontong Java , and Mid-Pacific Mountains , are located on thermal swells . Other oceanic plateaus, however, are made of rifted continental crust, for example the Falkland Plateau , Lord Howe Rise , and parts of Kerguelen , Seychelles , and Arctic ridges. Plateaus formed by large igneous provinces were formed by the equivalent of continental flood basalts such as the Deccan Traps in India and
187-685: The Snake River Plain in the United States. In contrast to continental flood basalts, most igneous oceanic plateaus erupt through young and thin (6–7 km (3.7–4.3 mi)) mafic or ultra-mafic crust and are therefore uncontaminated by felsic crust and representative for their mantle sources. These plateaus often rise 2–3 km (1.2–1.9 mi) above the surrounding ocean floor and are more buoyant than oceanic crust. They therefore tend to withstand subduction, more-so when thick and when reaching subduction zones shortly after their formations. As
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#1732844490959204-411: The highest amount of silicon (such rock is called felsic ). Oceanic crust has a smaller amount of silicon ( mafic rock). Igneous oceanic plateaus have a ratio intermediate between continental and oceanic crust, although they are more mafic than felsic. However, when a plate carrying oceanic crust subducts under a plate carrying an igneous oceanic plateau, the volcanism which erupts on the plateau as
221-427: The oceanic crust heats up on its descent into the mantle erupts material which is more felsic than the material which makes up the plateau. This represents a step toward creating crust which is increasingly continental in character, being less dense and more buoyant. If an igneous oceanic plateau is subducted underneath another one, or under existing continental crust, the eruptions produced thereby produce material that
238-527: The plateau produces the characteristic clockwise circulation current over the cap. The waters of the Flemish Cap are deeper and warmer than the Grand Banks of Newfoundland . The 58,000-square-kilometre area may have served as an important refuge for marine species during the last ice age . The Flemish Cap lies outside Canada 's 200 nautical mile (370 km) Exclusive Economic Zone established in 1977, and
255-616: The region by use of provisions of the Coastal Fisheries Protection Act and the United Nations Fish Stocks Agreement. According to early written accounts dating back to 1607, the Flemish Cap's name is a reminder that fishermen from Flanders were once active in the area. This area was filmed by Wolfgang Petersen in his 2000 film The Perfect Storm as the final fishing grounds of Andrea Gail , captained by Billy Tyne ( George Clooney ). Swordfish
272-445: The world, covering an area of 18,486,600 km (7,137,700 sq mi) or about 5.11% of the oceans. The South Pacific region around Australia and New Zealand contains the greatest number of oceanic plateaus (see map). Oceanic plateaus produced by large igneous provinces are often associated with hotspots , mantle plumes , and volcanic islands — such as Iceland, Hawaii, Cape Verde, and Kerguelen. The three largest plateaus,
289-428: Was their primary catch. 47°N 45°W / 47°N 45°W / 47; -45 Underwater plateau 3°03′S 160°23′E / 3.050°S 160.383°E / -3.050; 160.383 An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. There are 184 oceanic plateaus in
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