Elasticity of ferropericlase across the spin crossover in the Earth’s lower mantle
- Univ. of Texas, Austin, TX (United States). Department of Geological Sciences, Jackson School of Geosciences
- Univ. of Texas, Austin, TX (United States). Department of Geological Sciences, Jackson School of Geosciences; Center for High Pressure Science and Technology Advanced Research, (China)
- Institute for Study of the Earth's Interior, Misasa, Tottori (Japan)
The effects of the spin transition on the physics and chemistry of the lower-mantle ferropericlase and perovskite have been suggested to have significant consequences on the seismology and geochemistry. Knowing the elasticity of ferropericlase across the spin transition can help explain seismic and mineralogical models of the lower-mantle including the origin of seismic heterogeneities in the middle to lowermost parts of the lower mantle. However, full elastic tensors of ferropericlase within the spin transition and in the low-spin state remains experimentally controversial due to technical challenges in directly measuring sound velocities under lower-mantle conditions. Here we have reliably measured both VP and VS of a single-crystal ferropericlase ((Mg0.92,Fe0.08)O) using complementary Brillouin Light Scattering and Impulsive Stimulated Light Scattering coupled with diamond anvil cell (DAC) up to 96 GPa. The derived elastic tensors show drastically softened C11 and C12 within the spin transition at 40-60 GPa while C44 is not affected. Based on thermoelastic modelling along an expected geotherm, the spin crossover in ferropericlase can contribute to elastic abnormalities at mid lower-mantle conditions. Furthermore, our results imply the middle to lowermost parts of the lower mantle would exhibit enhanced seismic heterogeneities due to the occurrence of the mixed-spin and low-spin ferropericlase.
- Research Organization:
- Univ. of Chicago, Argonne, IL (United States); Carnegie Institution of Washington, Washington, D.C. (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC02-06CH11357; NA0002006
- OSTI ID:
- 1240833
- Alternate ID(s):
- OSTI ID: 1335494
- Journal Information:
- Scientific Reports, Vol. 5; ISSN 2045-2322
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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