Confirmation of their previous contiguous nature also came from the fossil plants Glossopteris and Gangamopteris, and the therapsid or mammal-like reptile Lystrosaurus, all widely distributed over South America, Africa, Antarctica, India, and Australia. [55] Often, these contributions are forgotten because: In 1947, a team of scientists led by Maurice Ewing utilizing the Woods Hole Oceanographic Institution's research vessel Atlantis and an array of instruments, confirmed the existence of a rise in the central Atlantic Ocean, and found that the floor of the seabed beneath the layer of sediments consisted of basalt, not the granite which is the main constituent of continents. [27][28] As oceanic lithosphere is formed at spreading ridges from hot mantle material, it gradually cools and thickens with age (and thus adds distance from the ridge). [90], On Earth-sized planets, plate tectonics is more likely if there are oceans of water. Mars is considerably smaller than Earth and Venus, and there is evidence for ice on its surface and in its crust. Geodesy Fundamentals … Wikipedia ?. It is more accurate to refer to this mechanism as gravitational sliding as variable topography across the totality of the plate can vary considerably and the topography of spreading ridges is only the most prominent feature. Metadata. 'pertaining to building')[1] is a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of Earth's lithosphere, since tectonic processes began on Earth between 3.3[2] and 3.5 billion years ago. Current plate boundaries are defined by their seismicity. basin analysis principles and application to petroleum. Tectonic sequence stratigraphy and dynamic geohistory. Such density variations can be material (from rock chemistry), mineral (from variations in mineral structures), or thermal (through thermal expansion and contraction from heat energy). The magnetic north and south poles reverse through time, and, especially important in paleotectonic studies, the relative position of the magnetic north pole varies through time. One of the most significant correlations discovered to date is that lithospheric plates attached to downgoing (subducting) plates move much faster than plates not attached to subducting plates. During the 1920s, 1930s and 1940s, the former reached important milestones proposing that convection currents might have driven the plate movements, and that spreading may have occurred below the sea within the oceanic crust. The result is a slight lateral incline with increased distance from the ridge axis. This includes the earthquake and volcanic regions which affect certain parts of the world. In the late 19th and early 20th centuries, geologists assumed that the Earth's major features were fixed, and that most geologic features such as basin development and mountain ranges could be explained by vertical crustal movement, described in what is called the geosynclinal theory. Furthermore, it was supposed that a static shell of strata was present under the continents. ?? This page was last changed on 20 October 2020, at 19:28. The latter is sometimes subdivided into the Indian and Australian plates. As part of this process, the upper 100-200 km layer of Earth cools and stiffens to form the lithosphere. orogeny wikipedia. Tectonic lithosphere plates consist of lithospheric mantle overlain by one or two types of crustal material: oceanic crust (in older texts called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). The division is based on differences in mechanical properties and in the method for the transfer of heat. ?? [41] Starting from the idea (also expressed by his forerunners) that the present continents once formed a single land mass (later called Pangea), Wegener suggested that these separated and drifted apart, likening them to "icebergs" of low density granite floating on a sea of denser basalt. Wikipedia English-Arabic glossary . Jump to: General, Art, Business, Computing, Medicine, Miscellaneous, Religion, Science, Slang, Sports, Tech, Phrases We found 2 dictionaries with English definitions that include the word global tectonics: Click on the first link on a line below to go directly to a page where "global tectonics" is defined. ), suggesting that they were formed during different epochs documenting the (already known from independent studies) normal and reversal episodes of the Earth's magnetic field. Global Tectonics by Philip Kearey, January 2008, Blackwell Publishers edition, Paperback in English - 3 edition The relative movement of the plates typically ranges from zero to 100 mm annually. From Simple English Wikipedia, the free encyclopedia, https://simple.wikipedia.org/w/index.php?title=Tectonics&oldid=7154192, Creative Commons Attribution/Share-Alike License. ofiolita wikipedia la enciclopedia libre. Plattektonik – Wikipedia. sources and further reading austhrutime com. The outer layers of the Earth are divided into the lithosphere and asthenosphere. Continental drift theory helps biogeographers to explain the disjunct biogeographic distribution of present-day life found on different continents but having similar ancestors. The concept that mountains had "roots" was confirmed by George B. Airy a hundred years later, during study of Himalayan gravitation, and seismic studies detected corresponding density variations. Global_plate_motion_2008-04-17.jpg ‎ (700 × 495 პიქსელი, ფაილიშ ზჷმა: 375 კბ, MIME ტიპი: image/jpeg) Plate tectonics The tectonic plates of the world were mapped in the second half of the 20th century. Oceanic crust is denser because it has less silicon and more heavier elements ("mafic") than continental crust ("felsic"). Wegener expanded his theory in his 1915 book The Origin of Continents and Oceans. A profound consequence of seafloor spreading is that new crust was, and still is, being continually created along the oceanic ridges. There are dozens of smaller plates, the seven largest of which are the Arabian, Caribbean, Juan de Fuca, Cocos, Nazca, Philippine Sea, and Scotia. In this hypothesis, the shifting of the continents can be simply explained by a large increase in the size of the Earth since its formation. The geometric fit between continents, such as between west Africa and South America is still an important part of plate reconstruction. It has also been suggested recently in Lovett (2006) that this observation may also explain why Venus and Mars have no plate tectonics, as Venus has no moon and Mars' moons are too small to have significant tidal effects on the planet. iks] (geology) Comprehensive theory relating the formation of mountain belts, island arcs, and ocean trenches to the relative movement of regionally extensive lithospheric plates which are delineated by the major seismic belts of the earth. Hess followed Heezen, suggesting that new oceanic crust continuously spreads away from the ridges in a conveyor belt–like motion. As the Earth spins eastward beneath the moon, the moon's gravity ever so slightly pulls the Earth's surface layer back westward, just as proposed by Alfred Wegener (see above). Este ficheiro está licenciado baixo a licenza Creative Commons recoñecemento compartir igual xenérico 2.5.: Vostede é libre de: compartir – copiar, distribuír e difundir a obra; facer obras derivadas – adaptar a obra; Baixo as seguintes condicións: recoñecemento – Debe indicar a debida atribución de autoría, fornecer unha ligazón á licenza, e indicar se se realizaron cambios. The new data that had been collected on the ocean basins also showed particular characteristics regarding the bathymetry. Ce modèle théorique a été constitué à partir du concept de dérive des continents , qui fut développé par Alfred Wegener au début du XX e siècle. Basin Analysis Principles and Application to Petroleum. Tidal drag due to the gravitational force the, Other smaller deformation effects of the crust due to wobbles and spin movements of the Earth rotation on a smaller time scale. the stripes are symmetrical around the crests of the mid-ocean ridges; at or near the crest of the ridge, the rocks are very young, and they become progressively older away from the ridge crest; the youngest rocks at the ridge crest always have present-day (normal) polarity; stripes of rock parallel to the ridge crest alternate in magnetic polarity (normal-reversed-normal, etc. They also found that the oceanic crust was much thinner than continental crust. This is based on the fact that rocks of different ages show a variable magnetic field direction, evidenced by studies since the mid–nineteenth century. as they relate to the causes and results of the dynamics of the crustal plates and sea floor spreading. Other mechanisms generating this gravitational secondary force include flexural bulging of the lithosphere before it dives underneath an adjacent plate which produces a clear topographical feature that can offset, or at least affect, the influence of topographical ocean ridges, and mantle plumes and hot spots, which are postulated to impinge on the underside of tectonic plates. This finding, though unexpected, was not entirely surprising because it was known that basalt—the iron-rich, volcanic rock making up the ocean floor—contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. [49] This had previously been estimated by its cooling rate under the assumption that the Earth's surface radiated like a black body. gravimetric) and geological observations, showed how the oceanic crust could disappear into the mantle, providing the mechanism to balance the extension of the ocean basins with shortening along its margins. Ironically, these systematic relations studies in the second half of the nineteenth century and the first half of the twentieth century underline exactly the opposite: that the plates had not moved in time, that the deformation grid was fixed with respect to the Earth equator and axis, and that gravitational driving forces were generally acting vertically and caused only local horizontal movements (the so-called pre-plate tectonic, "fixist theories"). There is debatable evidence of active tectonics in the planet's distant past; however, events taking place since then (such as the plausible and generally accepted hypothesis that the Venusian lithosphere has thickened greatly over the course of several hundred million years) has made constraining the course of its geologic record difficult. The same holds for the African, Eurasian, and Antarctic plates. Thus, the new mobilistic concepts neatly explained why the Earth does not get bigger with sea floor spreading, why there is so little sediment accumulation on the ocean floor, and why oceanic rocks are much younger than continental rocks. When newly formed rock cools, such magnetic materials recorded the Earth's magnetic field at the time. In the same paper the authors admit, however, that relative to the lower mantle, there is a slight westward component in the motions of all the plates. [85], Valles Marineris may be a tectonic boundary. Frederick Vine Wikipedia. The current motion of the tectonic plates is today determined by remote sensing satellite data sets, calibrated with ground station measurements. Dietz and Hess (the former published the same idea one year earlier in Nature,[58] but priority belongs to Hess who had already distributed an unpublished manuscript of his 1962 article by 1960)[59] were among the small handful who really understood the broad implications of sea floor spreading and how it would eventually agree with the, at that time, unconventional and unaccepted ideas of continental drift and the elegant and mobilistic models proposed by previous workers like Holmes. Plate tectonics (from the Late Latin: tectonicus, from the Ancient Greek: τεκτονικός, lit. [54] In this symposium, the evidence was used in the theory of an expansion of the global crust. Armed with the knowledge of a new heat source, scientists realized that the Earth would be much older, and that its core was still sufficiently hot to be liquid. New magma from deep within the Earth rises easily through these weak zones and eventually erupts along the crest of the ridges to create new oceanic crust. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which ride on the fluid-like (visco-elastic solid) asthenosphere. Global Tectonics By Philip Kearey Plattektonik – Wikipedia. sources and further reading austhrutime com. This was immediately followed by a symposium in Tasmania in March 1956. Many were published by European scientists and at first not mentioned or given little credit in the papers on sea floor spreading published by the American researchers in the 1960s. By the late 1920s, seismologists were beginning to identify several prominent earthquake zones parallel to the trenches that typically were inclined 40–60° from the horizontal and extended several hundred kilometers into the Earth. global tectonics by philip kearey ofiolita wikipedia la enciclopedia libre. plattektonik – wikipedia. [3], Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. These boundaries are discussed in further detail below. [39] The driving forces of plate motion continue to be active subjects of on-going research within geophysics and tectonophysics. ??? Plate boundaries are commonly associated with geological events such as earthquakes and the creation of topographic features such as mountains, volcanoes, mid-ocean ridges, and oceanic trenches. One of the first pieces of geophysical evidence that was used to support the movement of lithospheric plates came from paleomagnetism. Around the start of the twentieth century, various theorists unsuccessfully attempted to explain the many geographical, geological, and biological continuities between continents. Plattektonik – Wikipedia. The Himalayas, the world's tallest mountain range, are assumed to have been formed by the collision of two major plates. ???? In moderns views, gravity is invoked as the major driving force, through slab pull along subduction zones. However, despite its acceptance, it was long debated in the scientific community because the leading theory still envisaged a static Earth without moving continents up until the major breakthroughs of the early sixties. plattektonik – wikipedia. Global Tectonics By Philip Kearey orogeny wikipedia. They are associated with different types of surface phenomena. Plate tectonics geology ke baare me ek theory hae jisme dunia ke uppar waala layer ke baare me samjhawa jaawe hae. plate tectonics history of an idea ucmp. Exactly how this works is still a matter of debate. Gravitational sliding away from a spreading ridge: According to many authors,[clarification needed] plate motion is driven by the higher elevation of plates at ocean ridges. As old oceanic crust is "consumed" in the trenches (like Holmes and others, he thought this was done by thickening of the continental lithosphere, not, as now understood, by underthrusting at a larger scale of the oceanic crust itself into the mantle), new magma rises and erupts along the spreading ridges to form new crust. As explained above, tectonic plates may include continental crust or oceanic crust, and most plates contain both. The lithosphere is cooler and more rigid, while the asthenosphere is hotter and flows more easily. [76] Older reconstructions rely mainly on paleomagnetic pole data, although these only constrain the latitude and rotation, but not the longitude. This prediction of plate tectonics is also referred to as the conveyor belt principle. As it was observed early that although granite existed on continents, seafloor seemed to be composed of denser basalt, the prevailing concept during the first half of the twentieth century was that there were two types of crust, named "sial" (continental type crust) and "sima" (oceanic type crust). Tectonics is concerned with orogenies (mountain building) and major land features. Tectonics (from Latin, meaning "building") is a field within geology. sejarah bumi wikipedia bahasa indonesia ensiklopedia bebas. His paper, though little noted (and even ridiculed) at the time, has since been called "seminal" and "prescient". Since the early debates of continental drift, scientists had discussed and used evidence that polar drift had occurred because continents seemed to have moved through different climatic zones during the past. The mechanism is still advocated to explain the break-up of supercontinents during specific geological epochs. Furthermore, when the rock strata of the margins of separate continents are very similar it suggests that these rocks were formed in the same way, implying that they were joined initially. plattektonik – wikipedia. The debate is still open. This is a misnomer as nothing is "pushing" horizontally and tensional features are dominant along ridges. 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(2003); An updated digital model of plate boundaries, MORVEL plate velocity estimates and information, 750 million years of global tectonic activity, Multiple videos of plate tectonic movements, https://en.wikipedia.org/w/index.php?title=Plate_tectonics&oldid=999665330, Short description is different from Wikidata, Wikipedia indefinitely semi-protected pages, Articles containing Ancient Greek (to 1453)-language text, Articles with unsourced statements from November 2018, Wikipedia articles needing clarification from December 2020, Wikipedia articles needing clarification from December 2014, All articles with specifically marked weasel-worded phrases, Articles with specifically marked weasel-worded phrases from January 2016, Creative Commons Attribution-ShareAlike License. And Ireland contain rocks very similar in structure and lithology tectonicus, from the impact the., sannsynligvis lagt til av digitalkameraet eller skanneren som ble brukt til lage! 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