Seismic Evidence for Water Deep in Earth's Upper Mantle

Meijde, M. van der; Marone, Federica; Giardini, Domenico; Lee, Suzan van der

doi:10.1126/science.1083636

Cited by 154 publications

(68 citation statements)

References 24 publications

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“…On the other hand, the presence of water in the upper mantle and transition zone may help to reconcile some of the differences between the pyrolite model and seismic images (Jacobsen et al, 2008;Mao et al, 2008aMao et al, , 2008bMao et al, , 2011. Recent geological, mineralogical, and seismic studies have shown that various locations of the upper mantle and transition zone could be hydrated with up to 1 wt.% H 2 O in ringwoodite (Pearson et al, 2014;Schmandt et al, 2014;Song et al, 2004;van der Meijde et al, 2003). Since hydration can cause a greater reduction in the velocity of wadsleyite than olivine at mantle P-T conditions, the presence of a certain amount of water in the mantle will lower the velocity jump at the 410-km depth (Jacobsen et al, 2008;Mao et al, 2008aMao et al, , 2008bMao et al, , 2010Mao et al, , 2011, therefore making the velocity of pyrolite agree better with seismic observations of the upper mantle and the transition zone (Mao et al, 2008a(Mao et al, , 2008b(Mao et al, , 2011.…”

Section: The Velocity Contrast At the 410-km Depthmentioning

confidence: 94%

Elasticity of single-crystal olivine at high pressures and temperatures

Mao

Fan

Lin

et al. 2015

Earth and Planetary Science Letters

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Available online xxxx Editor: J. BrodholtKeywords: elasticity of single crystal San Carlos olivine high pressure and temperature metastable olivine wedge mantle seismic anisotropy Elasticity of single-crystal San Carlos olivine has been derived from sound velocity and density measurements at simultaneous high pressure-temperature conditions up to 20 GPa and 900 K using in situ Brillouin spectroscopy and single-crystal X-ray diffraction in externally-heated diamond anvil cells. These experimental results are used to evaluate the combined effect of pressure and temperature on full elastic constants of single-crystal olivine to better understand its velocity profiles and anisotropies in the deep mantle. Analysis of the results shows that the shear moduli display strong concave behaviors as a function of pressure at a given high temperature, while the longitudinal modulus, C 11 , and the off-diagonal moduli, C 12 and C 13 , exhibit greater temperature dependence at higher pressures than at relatively lower pressures. Using a finite-strain theory and thermal equation of state modeling for a pyrolitic mantle composition along an expected mantle geotherm, our results show that the magnitude of the V P and V S jumps at the 410-km depth are 6% and 6.4%, respectively, which are greater than that found in seismic observations, suggesting a mantle olivine content of 40-50 vol%, which is less than what is expected for the pyrolite model. Our modeled velocity profiles for a metastable olivine wedge in the subduction slabs along a representative cold slab geotherm are 6% and 10% lower than those of wadsleyite and ringwoodite, respectively, at corresponding depths of the normal mantle. Our modeled results also show that metastable olivine in the cold slabs could have strong V P and V S anisotropies. The maximum V P anisotropy is estimated to be 19-22% at transition zone depth, whereas the maximum V S splitting is 13-23% and increases with depth. As a result, the presence of a metastable olivine wedge at the transition zone depth would exhibit a seismic signature of low velocity and strong seismic anisotropy which are consistent with recent seismic observations for various locations of the slabs and can be used as mineral physics constraints for future seismic detections of the metastable olivine wedges in the deep mantle.

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Section: The Velocity Contrast At the 410-km Depthmentioning

confidence: 94%

Elasticity of single-crystal olivine at high pressures and temperatures

Mao

Fan

Lin

et al. 2015

Earth and Planetary Science Letters

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“…Therefore, we link the observation of Chen et al (2002) to the presence of both water and Fe 3+ in their run products. Thus, the seismic observations by van der Meijde et al (2003) that the 410-km has a varying thickness, between 390-440 Km, across the Earth may be related to both variable Fe 3+ and water incorporation.…”

Section: System Mgo-sio 2 ± H 2 Omentioning

confidence: 99%

“…Previous seismic tomographic observation evidence that the 410-km discontinuity is in some region of the Earth upper mantle quite sharp, i. e. 6 km, (Yamazaki et al 1994, Rost et al 2002 but much broader in other regions as shown by van der Meijde et al (2003): under the Mediterranean, the broadness varies between 20 and 30 km. This may be linked to variable water concentrations.…”

Section: Introductionmentioning

confidence: 99%

Water and Iron effect on the P-T-x coordinates of the 410-km discontinuity in the Earth upper mantle

Deon

Koch‐Müller

Rhede

et al. 2010

Contrib Mineral Petrol

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We performed multi-anvil experiments in the system MgO-SiO 2 ± H 2 O at 13.0-13.7 GPa and 1,025-1,300°C and in the system MgO-FeO-SiO 2 ± H 2 O, under reducing conditions, at 11.0-12.7 GPa and 1200°C, to depict the effect of H 2 O on the P-T-x coordinates of the 410-km discontinuity, i.e. the olivine-wadsleyite phase boundary. The charges were investigated with where wad-ring and ol-ring coexist, we observe, however, an unexpected broadening of the loops with a shift to higher iron contents. In total the stability field of hydrous wad expands in both directions, to lower and higher pressures. Fe 3+ concentrations as determined by EELS are very low and are expected to play no role in the broadening of the loops.

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“…Jacobsen et al 2004, Inoue et al 2004, Litasov and Ohtani 2007. A systematic knowledge of the compositional dependence of the physical properties of (Fe,Mg) 2 SiO 4 polymorphs can allow us to make substantial progresses in the interpretation of the fine details of seismic data relative to the upper mantle and transition zone and to understand the mechanism of water recycling in the deep Earth (Bercovici and Karato, 2003;van der Meijde et al, 2003;Blum and Shen, 2004;Hirschmann et al, 2005;Huang et al, 2005;Suetsugu et al, 2006).…”

Section: Introductionmentioning

confidence: 99%