Journal
NATURE
Volume 572, Issue 7771, Pages 643-+Publisher
NATURE PORTFOLIO
DOI: 10.1038/s41586-019-1483-x
Keywords
-
Categories
Funding
- NERC [NE/PO17657/1, NE/M00046X/1]
- French Government via the 'Investissements d'Avenir' programme [ANR-10-AIRT-05]
- NERC [NE/P017657/1, NE/P017525/1, hpc010001, NE/M00046X/1] Funding Source: UKRI
Ask authors/readers for more resources
Seismology records the presence of various heterogeneities throughout the lower mantle(1,2), but the origins of these signals-whether thermal or chemical-remain uncertain, and therefore much of the information that they hold about the nature of the deep Earth is obscured. Accurate interpretation of observed seismic velocities requires knowledge of the seismic properties of all of Earth's possible mineral components. Calcium silicate (CaSiO3) perovskite is believed to be the third most abundant mineral throughout the lower mantle. Here we simultaneously measure the crystal structure and the shear-wave and compressional-wave velocities of samples of CaSiO3 perovskite, and provide direct constraints on the adiabatic bulk and shear moduli of this material. We observe that incorporation of titanium into CaSiO3 perovskite stabilizes the tetragonal structure at higher temperatures, and that the material's shear modulus is substantially lower than is predicted by computations(3-5) or thermodynamic datasets(6). When combined with literature data and extrapolated, our results suggest that subducted oceanic crust will be visible as low-seismic-velocity anomalies throughout the lower mantle. In particular, we show that large low-shear-velocity provinces (LLSVPs) are consistent with moderate enrichment of recycled oceanic crust, and mid-mantle discontinuities can be explained by a tetragonal-cubic phase transition in Ti-bearing CaSiO3 perovskite.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available