Are facts about earths mantle

Answer 1

The mantle can be subdivided into the upper and lower mantle.

The uppermost part of the upper mantle is part of the lithosphere, and is sold and rigid. The lower part of the upper mantle is partially molten, and hence can flow.

The lower mantle is solid, but behaves in a plastic fashion, much like blu-tack.

The mantle is predominantly composed of an ultramafic rock called peridotite.

Further Detail:

The Earth's mantle is the largest layer of the Earth by volume accounting for around 84% of the Earth. It is approximately 2885 kilometers thick.

The Earth's mantle is composed of rocks that have higher concentrations of mafic minerals (containing iron and magnesium) and lower in concentrations of the felsic minerals (aluminum and silica) than the rocks of Earth's crust.

The concentrations of the above elements therefore mean that the Earth's mantle is composed of a series of minerals that are predominately calcium / iron / magnesium aluminum silicates.

Such as:

• Olivine - (Mg,Fe)2SiO4
• Pyroxene - X(Si,Al)2O6, where X represents either calcium, sodium, iron or magnesium
• Spinel - MgAl2O4
• Garnet - X3Y2(SiO4)3 where X and Y can be a mixture of aluminum, iron, calcium, manganese or magnesium.

At depths shallower than approximately 460 km, these minerals form the rocks types Peridotite, Dunite (Olivine-rich Peridotite), and Eclogite.

At depths greater than 410 km Olivine becomes unstable and is replaced by a number of different mineral forms known as poly-morphs which are stable at higher pressures. These include Wadsleyite which forms at depths between 410 and 520 km and Ringwoodite which forms between 520 and 600 km deep.

These depths are based on a number of seismic dicontinuities at the depths of 410 km (thought to mark the transition from Olivine to Wadsleyite) and at 520 km (thought to mark the transition from Wadsleyite to Ringwoodite) respectively.

At depths greater than around 650 km these upper mantle minerals start to become unstable due to the increased pressure and the minerals below this take the structure of the minerals Perovskite and Ferropericlase although with differing chemical compositions and it is this seismic discontinuity at 650 km depth that marks the transition to the lower mantle.
Its heat comes from left over radiation from the Earth's creation.
It is more denser than the crust. not

It contains more iron than silica.

It is 1800 miles thick and makes up more than two thirds of earts mass