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29-468: North Polar Basin may refer to: North Polar Basin (Mars) Arctic Basin , abyssal features within the Arctic Ocean [REDACTED] Topics referred to by the same term This disambiguation page lists articles about distinct geographical locations with the same name. If an internal link led you here, you may wish to change the link to point directly to

58-439: A diameter of 1,600–2,700 km (990–1,680 mi). Topographical data from Mars Global Surveyor are consistent with the models and also suggest that the elliptical crater has axes of length 10,600 km (6,600 mi) and 8,500 km (5,300 mi), centered on 67°N 208°E  /  67°N 208°E  / 67; 208 , though this has been partially obscured by later volcanic eruptions that created

87-479: A general increase in the rate of crustal formation for a period of 40 million years following the impact. Such a large impact would have disturbed the mantle , altering the normal convection currents and causing upwellings which further increase the amount of melting at the impact site. Overall, such an event would actually increase the rate of cooling of the Martian interior. The lack of magnetic anomalies observed in

116-801: A subduction zone cannot subduct much further than about 100 km (62 mi) before resurfacing. As a result, continental lithosphere is not recycled at subduction zones the way oceanic lithosphere is recycled. Instead, continental lithosphere is a nearly permanent feature of the Earth. Geoscientists can directly study the nature of the subcontinental mantle by examining mantle xenoliths brought up in kimberlite , lamproite , and other volcanic pipes . The histories of these xenoliths have been investigated by many methods, including analyses of abundances of isotopes of osmium and rhenium . Such studies have confirmed that mantle lithospheres below some cratons have persisted for periods in excess of 3 billion years, despite

145-415: Is a thermal boundary layer for the convection in the mantle. The thickness of the mantle part of the oceanic lithosphere can be approximated as a thermal boundary layer that thickens as the square root of time. h ∼ 2 κ t {\displaystyle h\,\sim \,2\,{\sqrt {\kappa t}}} Here, h {\displaystyle h} is the thickness of

174-436: Is capable of producing a sizable debris disk in Martian orbit, on the order of 5×10 kg, with a significant fraction of the material remaining close to Mars. This figure lies within the estimated mass range necessary to form the two moons, as other data suggests that only 1% of the mass of an accretion disk successfully forms moons. There are several other large impact basins on Mars that could have ejected enough debris to form

203-417: Is no thicker than the crust, but oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge. The oldest oceanic lithosphere is typically about 140 kilometres (87 mi) thick. This thickening occurs by conductive cooling, which converts hot asthenosphere into lithospheric mantle and causes the oceanic lithosphere to become increasingly thick and dense with age. In fact, oceanic lithosphere

232-408: Is the rigid, outermost rocky shell of a terrestrial planet or natural satellite . On Earth , it is composed of the crust and the lithospheric mantle , the topmost portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle are distinguished on the basis of chemistry and mineralogy . Earth's lithosphere, which constitutes

261-426: Is velocity of the lithospheric plate. Oceanic lithosphere is less dense than asthenosphere for a few tens of millions of years but after this becomes increasingly denser than asthenosphere. While chemically differentiated oceanic crust is lighter than asthenosphere, thermal contraction of the mantle lithosphere makes it more dense than the asthenosphere. The gravitational instability of mature oceanic lithosphere has

290-749: The Tharsis bulge along its rim. There is evidence for a secondary rim as well. This would make the North Polar Basin by far the largest impact crater in the Solar System , approximately four times the diameter of the next largest craters: Utopia Planitia , which is imbedded inside the North Polar Basin, the South Pole–Aitken basin on the Moon , and Hellas Planitia on Mars's southern hemisphere. This impact would have resulted in significant crustal melting and

319-426: The ocean basins . Continental lithosphere is associated with continental crust (having a mean density of about 2.7 grams per cubic centimetre or 0.098 pounds per cubic inch) and underlies the continents and continental shelves. Oceanic lithosphere consists mainly of mafic crust and ultramafic mantle ( peridotite ) and is denser than continental lithosphere. Young oceanic lithosphere, found at mid-ocean ridges ,

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348-438: The Earth." They have been broadly accepted by geologists and geophysicists. These concepts of a strong lithosphere resting on a weak asthenosphere are essential to the theory of plate tectonics . The lithosphere can be divided into oceanic and continental lithosphere. Oceanic lithosphere is associated with oceanic crust (having a mean density of about 2.9 grams per cubic centimetre or 0.10 pounds per cubic inch) and exists in

377-455: The Martian lithosphere , and the unusually low density and high porosity of Phobos, such that the moon would not be expected to remain aggregate if dynamically captured, suggest that the moons could have formed via accretion in Martian orbit, similar to how Earth's Moon formed. While estimates of the mass ejected by a large, Borealis-size impact vary, simulations suggest that a body approximately 0.02 Mars masses (~0.002 Earth Masses) in size

406-419: The asthenosphere deforms viscously and accommodates strain through plastic deformation . The thickness of the lithosphere is thus considered to be the depth to the isotherm associated with the transition between brittle and viscous behavior. The temperature at which olivine becomes ductile (~1,000 °C or 1,830 °F) is often used to set this isotherm because olivine is generally the weakest mineral in

435-518: The concept and introduced the term "lithosphere". The concept was based on the presence of significant gravity anomalies over continental crust, from which he inferred that there must exist a strong, solid upper layer (which he called the lithosphere) above a weaker layer which could flow (which he called the asthenosphere ). These ideas were expanded by the Canadian geologist Reginald Aldworth Daly in 1940 with his seminal work "Strength and Structure of

464-408: The continental lithosphere are billions of years old. Geophysical studies in the early 21st century posit that large pieces of the lithosphere have been subducted into the mantle as deep as 2,900 kilometres (1,800 mi) to near the core-mantle boundary, while others "float" in the upper mantle. Yet others stick down into the mantle as far as 400 kilometres (250 mi) but remain "attached" to

493-403: The continental plate above, similar to the extent of the old concept of "tectosphere" revisited by Jordan in 1988. Subducting lithosphere remains rigid (as demonstrated by deep earthquakes along Wadati–Benioff zone ) to a depth of about 600 kilometres (370 mi). Continental lithosphere has a range in thickness from about 40 kilometres (25 mi) to perhaps 280 kilometres (170 mi);

522-540: The deposits are inconsistent with the volcanic and glacial hypotheses. One recent investigation identified three impact craters in Acidalia Planitia as being the likely source of the hypothetical tsunamis, with the Lomonosov crater (pictured right) being the most likely candidate. Here, the tsunami generated by the impactor would have reached heights of 75 m (250 ft), and traveled 150 km (90 mi) past

551-437: The effect that at subduction zones, oceanic lithosphere invariably sinks underneath the overriding lithosphere, which can be oceanic or continental. New oceanic lithosphere is constantly being produced at mid-ocean ridges and is recycled back to the mantle at subduction zones. As a result, oceanic lithosphere is much younger than continental lithosphere: the oldest oceanic lithosphere is about 170 million years old, while parts of

580-559: The hard and rigid outer vertical layer of the Earth, includes the crust and the lithospheric mantle (or mantle lithosphere), the uppermost part of the mantle that is not convecting. The lithosphere is underlain by the asthenosphere which is the weaker, hotter, and deeper part of the upper mantle that is able to convect. 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

609-455: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=North_Polar_Basin&oldid=933020780 " Category : Place name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages North Polar Basin (Mars) Because the Borealis basin covers 40% of

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638-437: The moons. Analysis of Mars Global Surveyor data found mineral deposits similar to terminal moraines on Earth along the southern rim of the northern lowlands. Scientists have developed several theories to explain their presence, including: volcanic activity, glacial activity, and a series of Martian tsunamis . The arrangement of the deposits resembles deposits observed in recent tsunami events on Earth , and other features of

667-474: The northern hemisphere could be explained by such an impact, as the shock waves produced might have demagnetized the crust. However, some authors have instead argued that the inverse is more likely to be true, and that rather than the North Polar Basin being an impact basin, the Southern Hemisphere of Mars may have actually the site of the impact instead, and the thickness of the Southern Hemisphere crust

696-419: The oceanic mantle lithosphere, κ {\displaystyle \kappa } is the thermal diffusivity (approximately 1.0 × 10  m /s or 6.5 × 10  sq ft/min) for silicate rocks, and t {\displaystyle t} is the age of the given part of the lithosphere. The age is often equal to L/V, where L is the distance from the spreading centre of mid-oceanic ridge , and V

725-456: The southern rim. Dating techniques put the origin of the deposits sometime between the Late Hesperian and Early Amazonian periods, some 3 billion years ago, providing evidence to the presence of an ocean during this period. Lithosphere A lithosphere (from Ancient Greek λίθος ( líthos )  'rocky' and σφαίρα ( sphaíra )  'sphere')

754-477: The surface of Mars, and much of the Northern Hemisphere, many currently recognized regions of Mars lie within it: One possible explanation for the basin's low, flat and relatively crater-free topography is that the basin was formed by a single large impact. Two simulations of a possible impact sketched a profile for the collision: low velocity—6 to 10 km (3.7 to 6.2 mi) per second—oblique angle and

783-601: The upper approximately 30 to 50 kilometres (19 to 31 mi) of typical continental lithosphere is crust. The crust is distinguished from the upper mantle by the change in chemical composition that takes place at the Moho discontinuity . The oldest parts of continental lithosphere underlie cratons , and the mantle lithosphere there is thicker and less dense than typical; the relatively low density of such mantle "roots of cratons" helps to stabilize these regions. Because of its relatively low density, continental lithosphere that arrives at

812-524: The upper mantle. The lithosphere is subdivided horizontally into tectonic plates , which often include terranes accreted from other plates. The concept of the lithosphere as Earth's strong outer layer was described by the English mathematician A. E. H. Love in his 1911 monograph "Some problems of Geodynamics" and further developed by the American geologist Joseph Barrell , who wrote a series of papers about

841-414: Was as a result of impact-induced crust production. The origin of Mars' moons , Phobos and Deimos (pictured right), is unknown and remains controversial. One theory is that the moons are captured asteroids. However, the moons' near circular orbits and low inclination relative to the Martian equator are not in agreement with the capture hypothesis. The detection of minerals on Phobos similar to those in

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