|
Azores–Gibraltar Transform Fault
The Azores–Gibraltar Transform Fault (AGFZ), also called a fault zone and a fracture zone, is a major seismic zone in the Eastern Atlantic Ocean between the Azores and the Strait of Gibraltar. It is the product of the complex interaction between the African, Eurasian, and Iberian plates. The AGFZ produced these large-magnitude earthquakes and, consequently, a number of large tsunamis: 1755 Lisbon, 1761 Lisbon, 1816 North Atlantic, 1941 Gloria Fault earthquake, 1969 Horseshoe and 1975. Geologic setting Forming the Atlantic segment of the boundary between the African and Eurasian plates, the AGFZ is largely dominated by compressional forces between these converging () plates, but it is subject to a dynamic tectonic regime that also involves extension and transform faulting. The oceanic lithosphere in the area is directly related to the opening of the North Atlantic Ocean and is one of the oldest preserved on Earth. The western end of the AGFZ, the Azores Triple Junction on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle (Earth), upper mantle are distinguished on the basis of chemistry and mineralogy. Earth's lithosphere Earth's lithosphere, which constitutes the hard and rigid outer vertical layer of the Earth, includes the crust and the uppermost mantle. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, and deeper part of the upper mantle. The lithosphere–asthenosphere boundary is defined by a difference in response to stress. The lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere deforms viscously and accommodates strain through plasticity (physics), pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alboran Sea
The Alboran Sea (from Arabic , ''al-Baḥrān'') is the westernmost portion of the Mediterranean Sea, lying between the Iberian Peninsula and the north of Africa (Spain on the north and Morocco and Algeria on the south). The Strait of Gibraltar, which lies at the west end of the Alboran Sea, connects the Mediterranean with the Atlantic Ocean. Geography Its average depth is and maximum depth is . The International Hydrographic Organization defines the limits of the Alboran Sea as follows: ''On the West.'' The Eastern limit of the Strait of Gibraltar: A line joining from tip (Europa Point) of '' Cap Gibraltar'' in Europe to the tip of the ''Península de Almina'' of Ceuta in Africa (). ''On the East.'' A line joining from '' Cabo de Gata'' in Andalusia in Europe to ''Cap Fegalo'', near Oran, Algeria in Africa (). Several small islands dot the sea, including the eponymous Isla de Alborán. Most, even those close to the African shore, belong to Spain. Geology The Alboran domain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc Basin
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics. Structural characteristics Back-arc basins are typically very long and relatively narrow, often thousands of kilometers long while only being a few hundred kilometers wide at most. For back-arc extension to form, a subduction zone is required, but not all subduction zones have a back-arc extension feature. Back-arc basins are found in area ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tethys Ocean
The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents of Gondwana and Laurasia, before the opening of the Indian and Atlantic oceans during the Cretaceous Period. It was preceded by the Paleo-Tethys Ocean, which lasted between the Cambrian and the Early Triassic, while the Neotethys formed during the Late Triassic and lasted until the early Eocene (about 50 million years ago) when it completely closed. A portion known as the Paratethys formed during the Late Jurassic, was isolated during the Oligocene (34 million years ago) and lasted up to the Pliocene (about 5 million years ago), when it largely dried out. Many major seas and lakes of Europe and Western Asia, including the Mediterranean Sea, the Black Sea, the Caspian Sea, and the Aral Sea are thought to be remnants of the Paratethys. Ety ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant. The Sea has played a central role in the history of Western civilization. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago. The Mediterranean Sea covers an area of about , representing 0.7% of the global ocean surface, but its connection to the Atlantic via the Strait of Gibraltar—the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates the Iberian Peninsula in Europe from Morocco in Africa—is only wide. The Mediterranean Sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gibraltar Arc
The Gibraltar Arc is a geological region corresponding to an arcuate orogen surrounding the Alboran Sea, between the Iberian Peninsula and Africa. It consists of the Betic Cordillera (south Spain), and the Rif (North Morocco). The Gibraltar Arc is located at the western end of the Mediterranean Alpine belt and formed during the Neogene due to convergence of the Eurasian and African plates. Maximum altitudes of the region are reached at the Mulhacén peak at the Cordillera Betica. Precipitation is collected mainly by the Guadalquivir (Betics) and Sebou (Rif) rivers, which have delivered most sedimentary infill of the homonym sedimentary foreland basins.. Tectonic evolution North–south convergence of the Eurasian and African plates occurred during the middle Oligocene to the late Miocene, followed by northwest–southeast convergence from the late Tortonian to present. The Gibraltar Arc was formed during the Neogene due to a combination of western migration of the orogenic mount ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotia Arc
The Scotia Arc is the island arc system forming the north, east and south border of the Scotia Sea. The northern border, the North Scotia Ridge, comprises (from west to east) Isla de los Estados at the tip of Tierra del Fuego, the Burdwood, Davis, and Aurora Banks; the Shag, South Georgia Island and Clerke Rocks. The eastern border comprises the volcanic South Sandwich Islands flanked by the South Sandwich Trench. The southern border, the South Scotia Ridge, (east to west) comprises Herdman, Discovery, Bruce, Pirie, and Jane Banks; the South Orkney Islands and Elephant Island. The Bransfield Strait, finally, separates the arc from the South Shetland Islands and James Ross Island flanking the tip of the Antarctic Peninsula. The Scotia Arc surrounds the small Scotia and South Sandwich Plates. The arc is formed by continental fragments that once formed a land bridge between South America and Antarctica, once part of the subduction margin that still forms the Andes. An ancestral arc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lesser Antilles Volcanic Arc
The Lesser Antilles Volcanic Arc is a volcanic arc that forms the eastern boundary of the Caribbean Plate. It is part of a subduction zone, also known as the Lesser Antilles subduction zone, where the oceanic crust of the North American Plate is being subducted under the Caribbean Plate.The University of the West Indies Seismic Research CentreCaribbean Volcanoes Accessed: November 18, 2022. This subduction process formed a number of volcanic islands, from the Virgin Islands in the north to the islands off the coast of Venezuela in the south. The Lesser Antilles Volcanic Arc includes 21 'active' volcanoes, notably Soufriere Hills on Montserrat; Mount Pelée on Martinique; La Grande Soufrière on Guadeloupe; Soufrière Saint Vincent on Saint Vincent; Mount Scenery on Saba; and the submarine volcano Kick 'em Jenny which lies about north of Grenada. References * Macdonald, R., C.J. Hawkesworth, and E. Heath. (2000). The Lesser Antilles volcanic chain: a study in arc magmatism. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Margin
A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting creates new ocean basins. Eventually the continental rift forms a mid-ocean ridge and the locus of extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was originally created by rifting is known as a passive margin. Global distribution Passive margins are found at every ocean and continent boundary that is not marked by a strike-slip fault or a subduction zone. Passive margins define the region around the Arctic Ocean, Atlantic Ocean, and western Indian Ocean, and define the entire coasts of Africa, Australia, Greenland, and the Indian Subcontinent. They are also found on the east coast of North America and South America, in Western Europe and most of Antarctica. Northeas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horseshoe Abyssal Plain
A horseshoe is a fabricated product designed to protect a horse hoof from wear. Shoes are attached on the palmar surface (ground side) of the hooves, usually nailed through the insensitive hoof wall that is anatomically akin to the human toenail, although much larger and thicker. However, there are also cases where shoes are glued. Horseshoes are available in a wide variety of materials and styles, developed for different types of horse and for the work they do. The most common materials are steel and aluminium, but specialized shoes may include use of rubber, plastic, magnesium, titanium, or copper.Price, Steven D. (ed.) ''The Whole Horse Catalog: Revised and Updated'' New York:Fireside 1998 , pp. 84–87. Steel tends to be preferred in sports in which a strong, long-wearing shoe is needed, such as polo, eventing, show jumping, and western riding events. Aluminium shoes are lighter, making them common in horse racing where a lighter shoe is desired, and often facilitate certa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
