The Effect of Water on Mantle Phase Transitions

Ohtani, Eiji; Litasov, Konstantin D.

doi:10.2138/rmg.2006.62.17

Cited by 55 publications

(32 citation statements)

References 114 publications

(224 reference statements)

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“…The relationship of temperature and pressure is comparable to the numerical model results for the distribution of temperature in the Pacific slab (Tonegawa et al, 2008;Zhu et al, 2010). Thus, there is no phase change that occurs in our sample because of low temperature and short duration (Ohtani and Litasov, 2006;Perrillat et al, 2013). The olivine could persist well beyond its equilibrium boundary in metastable phase in cold subducting slab (Sung and Burns, 1976;Okal and Kirby, 1998;Tetzlaff and Schmeling, 2000;Mosenfelder et al, 2001).…”

Section: Discussionsupporting

confidence: 83%

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Hugoniot equation of state of olivine and its geodynamic implications

Huang

Yuan

Chen

et al. 2015

Sci. China Earth Sci.

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Large olivine samples were hot-pressed synthesized for shock wave experiments. The shock wave experiments were carried out at pressure range between 11 and 42 GPa. Shock data on olivine sample yielded a linear relationship between shock wave velocity D and particle velocity u described by D=3.56(0.13)+2.57(0.12)u. The shock temperature is determined by an energy relationship which is approximately 790°C at pressure 28 GPa. Due to low temperature and short experimental duration, we suggest that no phase change occurred in our sample below 30 GPa and olivine persisted well beyond its equilibrium boundary in metastable phase. The densities of metastable olivine are in agreement with the results of static compression. At the depth shallower than 410 km, the densities of metastable olivine are higher than those of the PREM model, facilitating cold slab to sink into the mantle transition zone. However, in entire mantle transition zone, the shock densities are lower than those of the PREM model, hampering cold slab to flow across the "660 km" phase boundary.

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Section: Discussionsupporting

confidence: 83%

“…Transformation rate likewise depends on temperature and pressure (Ohtani and Litasov, 2006). In the cold interior of subducting plates, the phase transformation from olivine to wadsleyite and to ringwoodite can be inhibited (Sung and Burns, 1976;Rubie and Ross, 1994;Kirby et al, 1996;Mosenfelder et al, 2001;Kubo et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Hugoniot equation of state of olivine and its geodynamic implications

Huang

Yuan

Chen

et al. 2015

Sci. China Earth Sci.

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“…The formation of active intraplate volcanism (such as the Changbai and Wudalianchi volcanoes), strong intraplate earthquakes, reactivation of the North China craton, the abundant oil and other natural mineral resources (such as the Daqing oil field), and a boundary in surface topography and gravity anomaly in eastern China are all related to the structure and dynamic processes in the BMW above the stagnant slab in the MTZ under East Asia (Zhao et al, 2010b. Mineral-physics studies have shown that deep slab dehydration in the MTZ is possible (e.g., Inoue et al, 2004;Ohtani et al, 2004;Ohtani and Litasov, 2006;Ohtani and Zhao, 2009). Recent results of shear-wave splitting Huang et al, 2011d), electrical conductivity (Ichiki et al, 2006), numerical modeling (Faccenna et al, 2010;Zhu et al, 2010), and geochemical analysis (Chen et al, 2007;Zou et al, 2008;Kuritani et al, 2009), all suggest a hot and wet upper-mantle above the stagnant Pacific slab and their close relationship to the intraplate volcanism and active tectonics in NE China, and so all support this BMW model (Fig.…”

Section: Stagnant Slab and Big Mantle Wedgementioning

confidence: 99%

Tomography and Dynamics of Western-Pacific Subduction Zones

Zhao¹

2012

Monogr. Environ. Earth Planets

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We review the significant recent results of multiscale seismic tomography of the Western-Pacific subduction zones and discuss their implications for seismotectonics, magmatism, and subduction dynamics, with an emphasis on the Japan Islands. Many important new findings are obtained due to technical advances in tomography, such as the handling of complex-shaped velocity discontinuities, the use of various later phases, the joint inversion of local and teleseismic data, tomographic imaging outside a seismic network, and P-wave anisotropy tomography. Prominent low-velocity (low-V ) and high-attenuation (low-Q) zones are revealed in the crust and uppermost mantle beneath active arc and back-arc volcanoes and they extend to the deeper portion of the mantle wedge, indicating that the low-V /low-Q zones form the sources of arc magmatism and volcanism, and the arc magmatic system is related to deep processes such as convective circulation in the mantle wedge and dehydration reactions in the subducting slab. Seismic anisotropy seems to exist in all portions of the Northeast Japan subduction zone, including the upper and lower crust, the mantle wedge and the subducting Pacific slab. Multilayer anisotropies with different orientations may have caused the apparently weak shear-wave splitting observed so far, whereas recent results show a greater effect of crustal anisotropy than previously thought. Deep subduction of the Philippine Sea slab and deep dehydration of the Pacific slab are revealed beneath Southwest Japan. Significant structural heterogeneities are imaged in the source areas of large earthquakes in the crust, subducting slab and interplate megathrust zone, which may reflect fluids and/or magma originating from slab dehydration that affected the rupture nucleation of large earthquakes. These results suggest that large earthquakes do not strike anywhere, but in only anomalous areas that may be detected with geophysical methods. The occurrence of deep earthquakes under the Japan Sea and the East Asia margin may be related to a metastable olivine wedge in the subducting Pacific slab. The Pacific slab becomes stagnant in the mantle transition zone under East Asia, and a big mantle wedge (BMW) has formed above the stagnant slab. Convective circulations and fluid and magmatic processes in the BMW may have caused intraplate volcanism (e.g., Changbai and Wudalianchi), reactivation of the North China craton, large earthquakes, and other active tectonics in East Asia. Deep subduction and dehydration of continental plates (such as the Eurasian plate, Indian plate and Burma microplate) are also found, which have caused intraplate magmatism (e.g., Tengchong) and geothermal anomalies above the subducted continental plates. Under Kamchatka, the subducting Pacific slab shortens toward the north and terminates near the Aleutian-Kamchatka junction. The slab loss was induced by friction with the surrounding asthenosphere, as the Pacific plate rotated clockwise 30 Ma ago, and then it was enlarged by the slab-edge pinch-off b...

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“…Additionally, the compressional anisotropies of these carbonates can be possibly affected. Last, the structural stabilities may also be modified, because the hydroxyl can affect the phase boundaries (Ohtani 2006). Hence, the presence of hydroxyl in the structure of carbonates can largely affect our knowledge of the composition of the Earth's interior, and it is necessary to take into account the effect of hydroxyl of on carbonates when modeling the Earth's global carbon cycle and investigating the influence of carbonates on the physical and chemical properties of the Earth's mantle.…”

Section: Discussionmentioning

confidence: 99%