THE MANTLE: UPSC Daily Important Topic | 13 February 2022

THE MANTLE

◇ It forms about 83 per cent of the earth’s volume and holds 67% of the earth’s mass.

◇  It extends from Moho’s discontinuity to a depth of 2,900 km.

◇ The density of the upper mantle varies between 2.9 g/cm3 and 3.3 g/cm3.

◇ The lower mantle extends beyond the asthenosphere. It is in a solid state.

◇ The density ranges from 3.3 g/cm3 to 5.7 g/cm3 in the lower mantle.

◇ The mantle is composed of silicate rocks that are rich in iron.

◇ Regarding its constituent elements, the mantle is made up of 45% oxygen, 21% silicon, and 23% magnesium (OSM).

◇ Temperatures range from approximately 200 °C at the upper boundary with the crust to approximately 4,000 °C at the core-mantle boundary.

◇ Because of the temperature difference, there is a convective material circulation in the mantle (although solid, the high temperatures within the mantle cause the silicate material to be sufficiently ductile).