Indoor seismology by probing the Earth interior by using sound velocity measurements at high pressures and temperatures
The adiabatic bulk (K S) and shear (G) moduli of mantle materials at high pressure and temperature can be obtained directly by measuring compressional and shear wave velocities in the laboratory with experimental techniques based on physical acoustics. We present the application of the current state-of-the-art experimental techniques by using ultrasonic interferometry in conjunction with synchrotron x radiation to study the elasticity of olivine and pyroxenes and their high-pressure phases. By using these updated thermoelasticity data for these phases, velocity and density profiles for a pyrolite model are constructed and compared with radial seismic models. We conclude that pyrolite provides an adequate explanation of the major seismic discontinuities at 410- and 660-km depths, the gradient in the transition zone, as well as the velocities in the lower mantle, if the uncertainties in the modeling and the variations in different seismic models are considered. The characteristics of the seismic scaling factors in response to thermal anomalies suggest that anticorrelations between bulk sound and shear wave velocities, as well as the large positive density anomalies observed in the lower mantle, cannot be explained fully without invoking chemical variations.
- Research Organization:
- BROOKHAVEN NATIONAL LABORATORY (BNL), NATIONAL SYNCHROTRON LIGHT SOURCE (NSLS)
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 930437
- Report Number(s):
- BNL-81182-2008-JA; PNASA6; TRN: US0901388
- Journal Information:
- Proceedings of the National Academy of Sciences of the USA, Vol. 104, Issue 22; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
Similar Records
Elasticity of Hydrous Wadsleyite to 12 GPa: Implications for Earth's Transition Zone
Characteristics of Lateral Heterogeneities with Thermal and Chemical Origins in the Pyrolitic Lower Mantle