| Autor: |
Alexei Kuznetsov, Jung-Fu Lin, György Vankó, Steven D. Jacobsen, Vitali B. Prakapenka, Choong-Shik Yoo, V. Iota, Viktor V. Struzhkin |
| Rok vydání: |
2007 |
| Předmět: |
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| Zdroj: |
Science (New York, N.Y.). 317(5845) |
| ISSN: |
1095-9203 |
| Popis: |
Mineral properties in Earth's lower mantle are affected by iron electronic states, but representative pressures and temperatures have not yet been probed. Spin states of iron in lower-mantle ferropericlase have been measured up to 95 gigapascals and 2000 kelvin with x-ray emission in a laser-heated diamond cell. A gradual spin transition of iron occurs over a pressure-temperature range extending from about 1000 kilometers in depth and 1900 kelvin to 2200 kilometers and 2300 kelvin in the lower mantle. Because low-spin ferropericlase exhibits higher density and faster sound velocities relative to the high-spin ferropericlase, the observed increase in low-spin (Mg,Fe)O at mid-lower mantle conditions would manifest seismically as a lower-mantle spin transition zone characterized by a steeper-than-normal density gradient. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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