Details

Autor(en) / Beteiligte

• Irifune, Tetsuo
• Shinmei, Toru
• McCammon, Catherine A
• Miyajima, Nobuyoshi
• Rubie, David C
• Frost, Daniel J

Titel

Iron Partitioning and Density Changes of Pyrolite in Earth's Lower Mantle

Ist Teil von

• Science (American Association for the Advancement of Science), 2010-01, Vol.327 (5962), p.193-195

Ort / Verlag

Washington, DC: American Association for the Advancement of Science

Erscheinungsjahr

2010

Quelle

Science Online科学在线

Beschreibungen/Notizen

• Phase transitions and the chemical composition of minerals in Earth's interior influence geophysical interpretations of its deep structure and dynamics. A pressure-induced spin transition in olivine has been suggested to influence iron partitioning and depletion, resulting in a distinct layered structure in Earth's lower mantle. For a more realistic mantle composition (pyrolite), we observed a considerable change in the iron-magnesium partition coefficient at about 40 gigapascals that is explained by a spin transition at much lower pressures. However, only a small depletion of iron is observed in the major high-pressure phase (magnesium silicate perovskite), which may be explained by preferential retention of the iron ion Fe³⁺. Changes in mineral proportions or density are not associated with the change in partition coefficient. The observed density profile agrees well with seismological models, which suggests that pyrolite is a good model composition for the upper to middle parts of the lower mantle.