Tracking silica in Earth's upper mantle using new sound velocity data for coesite to 5.8 GPa and 1073 K
| Autor: | Ying Li, Baosheng Li, Yongtao Zou, Robert C. Liebermann, Ting Chen, Xintong Qi |
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| Rok vydání: | 2017 |
| Předmět: |
Ultrasonic interferometry
010504 meteorology & atmospheric sciences Subduction Mineralogy Geophysics engineering.material 010502 geochemistry & geophysics 01 natural sciences Mantle (geology) Shear (geology) Coesite S-wave engineering General Earth and Planetary Sciences Eclogite Geology 0105 earth and related environmental sciences Stishovite |
| Zdroj: | Geophysical Research Letters. 44:7757-7765 |
| ISSN: | 0094-8276 |
| Popis: | The compressional and shear wave velocities for coesite have been measured simultaneously up to 5.8 GPa and 1073 K by ultrasonic interferometry for the first time. The shear wave velocity decreases with pressure along all isotherms. The resulting contrasts between coesite and stishovite reach ~34% and ~45% for P and S wave velocities, respectively, and ~64% and ~75% for their impedance at mantle conditions. The large velocity and impedance contrasts across coesite-stishovite transition imply that, to generate the velocity and impedance contrasts observed at the X-discontinuity, only a small amount of silica would be required. The velocity jump dependences on silica, d(lnVP)/d(SiO2) = 0.38 (wt%)-1 and d(lnVS)/d(SiO2) = 0.52 (wt%)-1, are utilized to place constraints on the amount of silica in the upper mantle, and provide a geophysical approach to track mantle eclogite materials and ancient subducted oceanic slabs. |
| Databáze: | OpenAIRE |
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