Lower mantle

Common card · No. 414639

The lower mantle, historically also called the mesosphere, occupies about 56% of the total volume of Earth, and is the region from 660 to 2,890 km (410 to 1,800 mi) below Earth's surface; between the transition zone and the outer core. The preliminary reference Earth model (PREM) separates the lower mantle into three sections, the uppermost (660–770 km (410–480 mi)), mid-lower mantle (770–2,700 km (480–1,680 mi)), and the D layer (2,700–2,890 km (1,680–1,800 mi)). Pressure and temperature in the lower mantle range from 24–127 GPa (3,500,000–18,400,000 psi) and 1,900–2,600 °C (2,170–2,870 K; 3,450–4,710 °F). It has been proposed that the composition of the lower mantle is pyrolitic, containing three major phases of bridgmanite, ferropericlase, and davemaoite. The high pressure in the lower mantle has been shown to induce a spin transition of iron-bearing bridgmanite and ferropericlase, which may affect both mantle plume dynamics and lower mantle chemistry. The mantle moves at about 1 cm...

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