Orthorhombic perovskite phases observed in olivine,pyroxene and garnet at high pressures and temperatures |
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| Authors: | Lin-Gun Liu |
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| Institution: | Research School of Earth Sciences, Australian National University, Canberra, A.C.T.Australia |
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| Abstract: | Ferromagnesian silicate olivines, pyroxenes and garnets with Mg/(Mg + Fe)?0.3 (molar) have been found to transform to high-pressure phases characterized by the orthorhombic perovskite structure when compressed to pressures above 250 kbar in a diamond-anvil press and heated to temperatures above 1,000°C with a YAG laser. The zero-pressure density of the perovskite phase of (Mg,Fe)SiO3 is about 3–4% greater than that of the close-packed oxides, rocksalt plus stishovite. For (Mg,Fe)2SiO4 compounds, the perovskite plus rocksalt phase assemblage is 2–3% denser than the mixed oxides. The experimental synthesis of such high-density perovskite phases in olivine, pyroxene and garnet compounds suggests that (Mg,Fe)SiO3-perovskite is the dominant mineral phase in the earth's lower mantle. |
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