MEASUREMENT OF P AND S SOUND VELOCITIES UNDER PRESSURE OF LABORATORY MODELS OF THE EARTH'S MANTLE
Abstract
The techniques of ultrasonic interferometry were used to measure the isotropic sound velocities and their derivatives for polycrystalline specimens of aluminum oxide and magnesium oxide. The pressure derivatives were determined to 4 kbars at room temperature and at -78.5 C. The temperature derivatives were measured at 1 atm. The isothermal pressure derivatives of the bulk modulus were determined. From these data, the critical temperature gradient for velocities, (dT/dP)v, were evaluated, and the velocity behavior of these materials as a function of temperature and depth in the mantle, are discussed. It was found that, because (dT/dP)vp > (dT/dP)vs, they exhibit a shear velocity minimum and a less pronounced longitudinal velocity minimum under conditions likely to exist in the upper mantle. An expression was derived, employing the measured values of the bulk modulus B(o) and its pressure derivative B(o'), which predicts compression at extremely high pressures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 16, 1965
- Accession Number
- AD0478109
Entities
People
- Edward Schreiber
- Orson L. Anderson