Anticorrelated seismic velocity anomalies from post-perovskite in the lowermost mantle
Science
By: Alexander R. Hutko, T. Lay, Justin Revenaugh, and E.J. Garnero
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Abstract
Earth's lowermost mantle has thermal, chemical, and mineralogical complexities that require precise seismological characterization. Stacking, migration, and modeling of over 10,000 P and S waves that traverse the deep mantle under the Cocos plate resolve structures above the core-mantle boundary. A small -0.07 ?? 0.15% decrease of P wave velocity (Vp) is accompanied by a 1.5 ?? 0.5% increase in S wave velocity (Vs) near a depth of 2570 km. Bulk-sound velocity [Vb = (V p2 - 4/3Vs2)1/2] decreases by -1.0 ?? 0.5% at this depth. Transition of the primary lower-mantle mineral, (Mg1-x-y FexAly)(Si,Al) O3 perovskite, to denser post-perovskite is expected to have a negligible effect on the bulk modulus while increasing the shear modulus by ???6%, resulting in local anticorrelation of Vb and Vs anomalies; this behavior explains the data well.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Anticorrelated seismic velocity anomalies from post-perovskite in the lowermost mantle |
| Series title | Science |
| DOI | 10.1126/science.1155822 |
| Volume | 320 |
| Issue | 5879 |
| Year Published | 2008 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Science |
| First page | 1070 |
| Last page | 1074 |
| Google Analytic Metrics | Metrics page |