Amantle is a layer inside aplanetary body bounded below by acore and above by acrust. Mantles are made ofrock orices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergonedifferentiation bydensity. Allterrestrial planets (includingEarth), half of thegiant planets, specificallyice giants, a number ofasteroids, and some planetarymoons have mantles.
TheEarth's mantle is a layer ofsilicate rock between thecrust and theouter core. Its mass of 4.01 × 1024 kg is 67% of the mass of the Earth.[1] It has a thickness of 2,900 kilometres (1,800 mi)[1] making up about 84% of Earth's volume. It is predominantly solid, but ingeological time it behaves as aviscousfluid.Partial melting of the mantle atmid-ocean ridges producesoceanic crust, and partial melting of the mantle atsubduction zones producescontinental crust.[2]
Mercury has a silicate mantle approximately 490 kilometers (300 miles) thick, constituting only 28% of its mass.[1]Venus's silicate mantle is approximately 2,800 kilometers (1,700 miles) thick, constituting around 70% of its mass.[1]Mars's silicate mantle is approximately 1,600 kilometers (990 miles) thick, constituting ~74–88% of its mass,[1] and may be represented bychassignite meteorites.Uranus andNeptune's ice mantles are approximately 30,000 km thick, composing 80% of both masses.[3]
Jupiter's moonsIo,Europa, andGanymede have silicate mantles; Io's ~1,100 kilometers (680 miles) silicate mantle 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.[1]
The silicate mantle of theEarth's moon is approximately 1300–1400 km thick, and is the source ofmare basalts.[4] The lunar mantle might be exposed in theSouth Pole-Aitken basin or theCrisium basin.[4] The lunar mantle contains a seismic discontinuity at ~500 kilometers (310 miles) depth, most likely related to a change in composition.[4]
Titan andTriton each have a mantle made ofice or othersolid volatile substances.[5][6]
Some of the largestasteroids have mantles;[7] for example,Vesta has a silicate mantle similar in composition todiogenite meteorites.[8]
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