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Solidus of Earth's deep mantle
1A. Zerr and R. Boehler, Max-Planck-Institut fur Chemie, Postfach 3060, 55020 Mainz, Germany. A. Diegeler, Institut fur Mineralogie und Geochemie der Universitat zu Koln, 50674 Koln, Germany.
Science (New York, N.Y.)
|July 10, 1998
Summary
The solidus temperature of the lower mantle was measured, revealing it is significantly lower than previously thought. This suggests partial melting of the deep mantle is possible near the core-mantle boundary.
Area of Science:
- Geophysics
- Mineral Physics
- High-Pressure Science
Background:
- The lower mantle's composition and thermal state are crucial for understanding mantle dynamics.
- Previous studies have limited data on the solidus of lower mantle materials at extreme pressures.
Purpose of the Study:
- To experimentally determine the solidus temperature of a pyrolite-like composition relevant to the lower mantle.
- To assess the potential for partial melting in the deep Earth.
Main Methods:
- Utilized a diamond anvil cell (DAC) for high-pressure generation.
- Employed CO2 laser heating to reach extreme temperatures within the DAC.
- Measured the solidus of a pyrolite-like composition up to 59 gigapascals.
Main Results:
- The solidus temperatures were found to be at least 700 K below the melting temperatures of magnesiowustite.
- In the deep mantle, the solidus is over 1500 K above the average geotherm.
- However, near the core-mantle boundary, the solidus approaches the core temperature.
Conclusions:
- Partial melting of the lower mantle is plausible, particularly at the core-mantle boundary.
- The findings have significant implications for mantle convection and geochemical cycling.
- This research refines our understanding of deep Earth thermal regimes and phase transitions.