The composition and physical properties of the Earth's mantle and core

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:6864485

Knittle, E B

The chemical and physical properties of the Earth's deep interior, particularly the mantle and core, have controlled both the dynamics and the evolution of the planet. Seismic studies are only capable of determining the velocity of seismic waves and, in an average sense, densities at depth. The physical interpretation of seismic results relies on understanding the properties of materials. The experiments allow comparisons to be made between high pressure experiments and corresponding seismological observations, providing insight into the Earth's large-scale chemical structure. Electrical resistivity measurements to pressures of 83 GPa and temperatures ranging from 300 K to 4300 K confirm the presence of both crystalline and liquid metallic phases of FeO at pressures above 60 to 70 GPa and temperatures above 1000 K. By experimentally determining the melting temperature of FeO to 100 GPa, and of a model core composition at 83 GPa, it was found that the solid-melt equilibria can be described by complete solid solution across the Fe-FeO system at pressures above 70 GPa. The data suggest that the temperature at the Earth's core-mantle boundary is close to 4800 (+ or - 500) K. The thermal expansion of silicate perovskite, the most abundant in the Earth's lower mantle, was measured between 300 and 840 K at zero pressure. These data are combined with the 300 K isotherm of silicate perovskite, measured to pressures of 112 GPa, to obtain a thermal equation of state for this mineral. The thermal equation of state allows comparisons to be made between the physical properties of silicate perovskite and mineral assemblages dominated by perovskite with the same properties for lower mantle as determined by seismology. Chemical reactions between silicate perovskite and liquid iron were documented at pressures greater than 70 G

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 6864485
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
EARTH PLANET
CHEMICAL COMPOSITION
PHYSICAL PROPERTIES
CHEMICAL REACTIONS
ELECTRIC CONDUCTIVITY
EQUATIONS OF STATE
HIGH PRESSURE
IRON
IRON ALLOYS
ISOTHERMS
MELTING
PEROVSKITES
SEISMIC WAVES
SEISMOLOGY
SILICA
SILICATES
THERMAL EXPANSION
ALLOYS
CHALCOGENIDES
ELECTRICAL PROPERTIES
ELEMENTS
EQUATIONS
EXPANSION
METALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PLANETS
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENTS
580000* - Geosciences