Lower mantle (Earth) | Wikipedia audio article
Channel: wikipedia tts
Date: 2019-05-16

This is an audio version of the Wikipedia Article:
https://en.wikipedia.org/wiki/Lower_mantle_(Earth)


00:01:13 1 Physical properties
00:03:09 2 Composition
00:05:39 3 Spin transition zone



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SUMMARY
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The lower mantle represents approximately 56% of the Earth's total volume and is located 660–2900 km below the Earth's surface in 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), mid-lower mantle (770–2700 km), and the D" layer (2700–2900 km). Pressures and temperature at the lower mantle ranges from 24-127 GPa and 1900-2600K. It has been proposed that the composition of the lower mantle is pyrolitic containing three major phases of bridgmanite, ferropericlase and calcium-silicate perovskite. The pressure conditions in the lower mantle was shown to induce a spin transition of iron-bearing bridgmanite and ferropericlase which may affect both mantle plume dynamics and lower mantle chemistry.