Melting of (Mg,Fe)2SiO4 at the Core-Mantle Boundary of the Earth

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Science  14 Mar 1997:
Vol. 275, Issue 5306, pp. 1623-1625
DOI: 10.1126/science.275.5306.1623

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The lower mantle of the Earth is believed to be largely composed of (Mg,Fe)O (magnesiowüstite) and (Mg,Fe)SiO3 (perovskite). Radiative temperatures of single-crystal olivine [(Mg0.9,Fe0.1)2SiO4] decreased abruptly from 7040 ± 315 to 4300 ± 270 kelvin upon shock compression above 80 gigapascals. The data indicate that an upper bound to the solidus of the magnesiowüstite and perovskite assemblage at 4300 ± 270 kelvin is 130 ± 3 gigapascals. These conditions correspond to those for partial melting at the base of the mantle, as has been suggested occurs within the ultralow-velocity zone beneath the central Pacific.

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