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24-463: Earth's lithosphere, which constitutes 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

48-429: A mean density of about 2.9 grams per cubic centimetre or 0.10 pounds per cubic inch) and exists in 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

72-750: 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

96-523: Is 67% the mass of the Earth. It has a thickness of 2,900 kilometres (1,800 mi) making up about 84% of Earth's volume. It is predominantly solid, but in geological time it behaves as a viscous fluid . Partial melting of the mantle at mid-ocean ridges produces oceanic crust , and partial melting of the mantle at subduction zones produces continental crust . Mercury has a silicate mantle approximately 490 kilometers (300 miles) thick, constituting only 28% of its mass. Venus 's silicate mantle

120-485: Is approximately 2,800 kilometers (1,700 miles) thick, constituting around 70% of its mass. Mars 's silicate mantle is approximately 1,600 kilometers (990 miles) thick, constituting ~74–88% of its mass, and may be represented by chassignite meteorites. Uranus and Neptune 's ice mantles are approximately 30,000 km thick, composing 80% of both masses. Jupiter 's moons Io , Europa , and Ganymede have silicate mantles; Io's ~1,100 kilometers (680 miles) silicate mantle

144-516: 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 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)

168-410: Is denser than continental lithosphere. Young oceanic lithosphere, found at mid-ocean ridges , 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

192-487: Is often used to set this isotherm because olivine is generally the weakest mineral in 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

216-491: Is overlain by a volcanic crust, Ganymede's ~1,315 kilometers (817 miles) thick silicate mantle is overlain by ~835 kilometers (519 miles) of ice, and Europa's ~1,165 kilometers (724 miles) km silicate mantle is overlain by ~85 kilometers (53 miles) of ice and possibly liquid water. The silicate mantle of the Earth's moon is approximately 1300–1400 km thick, and is the source of mare basalts . The lunar mantle might be exposed in

240-576: Is the thermal conductivity divided by density and specific heat capacity at constant pressure. It is a measure of the rate of heat transfer inside a material. It has units of m /s. Thermal diffusivity is usually denoted by lowercase alpha ( α ), but a , h , κ ( kappa ), K , , D , D T {\displaystyle D_{T}} are also used. The formula is: α = k ρ c p {\displaystyle \alpha ={\frac {k}{\rho c_{p}}}} where Together, ρc p can be considered

264-436: Is the thickness of 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

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288-425: 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

312-632: The South Pole-Aitken basin or the Crisium basin . The lunar mantle contains a seismic discontinuity at ~500 kilometers (310 miles) depth, most likely related to a change in composition. Titan and Triton each have a mantle made of ice or other solid volatile substances. Some of the largest asteroids have mantles; for example, Vesta has a silicate mantle similar in composition to diogenite meteorites. Thermal diffusivity In heat transfer analysis, thermal diffusivity

336-401: The volumetric heat capacity (J/(m ·K)). As seen in the heat equation , ∂ T ∂ t = α ∇ 2 T , {\displaystyle {\frac {\partial T}{\partial t}}=\alpha \nabla ^{2}T,} one way to view thermal diffusivity is as the ratio of the time derivative of temperature to its curvature , quantifying

360-490: The American geologist Joseph Barrell , who wrote a series of papers about 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

384-497: The Canadian geologist Reginald Aldworth Daly in 1940 with his seminal work "Strength and Structure of 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

408-403: 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

432-400: 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);

456-437: 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

480-421: The mantle flow that accompanies plate tectonics. The upper part of the lithosphere is a large habitat for microorganisms , with some found more than 4.8 km (3 mi) below Earth's surface. Mantle (geology) A mantle is a layer inside a planetary body bounded below by a core and above by a crust . Mantles are made of rock or ices , and are generally the largest and most massive layer of

504-487: The oceanic lithosphere to become increasingly thick and dense with age. In fact, oceanic lithosphere 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}

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528-419: The planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density . All terrestrial planets (including Earth ), half of the giant planets , specifically ice giants , a number of asteroids , and some planetary moons have mantles. The Earth's mantle is a layer of silicate rock between the crust and the outer core . Its mass of 4.01 × 10 kg

552-432: The rate at which temperature concavity is "smoothed out". Thermal diffusivity is a contrasting measure to thermal effusivity . In a substance with high thermal diffusivity, heat moves rapidly through it because the substance conducts heat quickly relative to its volumetric heat capacity or 'thermal bulk'. Thermal diffusivity is often measured with the flash method . It involves heating a strip or cylindrical sample with

576-603: 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

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