The fate of subducted basaltic crust in the Earth's lower mantle

Hirose, Kei; Fei, Yingwei; Ma, Yanwei; Mao, Ho‐kwang

doi:10.1038/16225

Cited by 377 publications

(247 citation statements)

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“…It is notable that the basaltic layer at the top of the subducting slab has a high concentration of Al and some seismic studies have suggested that the subducting slabs reach CMB (40). In addition, the basaltic layers become negatively buoyant in the lower mantle (41) and likely are transported to the CMB. Therefore, possible accumulation of basaltic materials at the CMB is also a candidate for the high electrical conductivity at the CMB, as Fe 3+ -O bonding becomes metallic at deep mantle P as found in this study.…”

Section: Resultsmentioning

confidence: 99%

Electronic and magnetic structures of the postperovskite-type Fe ₂ O ₃ and implications for planetary magnetic records and deep interiors

Shim

Bengtson

Morgan³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Section: Resultsmentioning

confidence: 99%

Electronic and magnetic structures of the postperovskite-type Fe ₂ O ₃ and implications for planetary magnetic records and deep interiors

Shim

Bengtson

Morgan³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…(The phase boundary will be referred to as the "660-km phase boundary" hereinafter, though, strictly speaking, the depth of ¾-spinel versus postspinel transition is not 660-km in Venus.) The end-member B is gradually transformed into its high-pressure phase in a depth range around 660-km, as is the case for the garnet versus perovskite transition [Irifune and Ringwood, 1993;Hirose et al, 1999]. The density of the convecting material depends on its temperature, composition, and phase.…”

Section: Introductionmentioning

confidence: 99%

Numerical models of magmatism in convecting mantle with temperature‐dependent viscosity and their implications for Venus and Earth

Ogawa¹

2000

J. Geophys. Res.

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Abstract. Numerical models are presented for magmatism in a convecting mantle that contains internal heat source. Mantle convection is modeled by a convection of binary eutectic material with Newtonian temperature-dependent rheology driven by thermal, compositional, and melt buoyancy as well as the buoyancy from the "660-km" phase transitions. Mantle magmatism is modeled by a gravitationally induced permeable flow of magma generated by pressure release melting through matrix. Magma mostly has the eutectic composition, that is, basaltic composition. The numerical models suggest that magmatism and mantle convection strongly influence each other to form a coupled system when the internal heating is sufficiently strong. Episodic magmatism takes place to chemically differentiate the mantle; basaltic materials occupy deeper part of the lower mantle, while magma residue occupies the uppermost mantle. Compositional buoyancy of the differentiated materials makes mantle convection sluggish except when magmatic activities take place. The style of magmatism and mantle convection depends on the viscosity contrast across the cold thermal boundary layer (TBL) along the top surface boundary. When the viscosity contrast is large, the fluid in the coldest part of top TBL becomes a stagnant lid and a conspicuous lateral heterogeneity arises in the upper mantle. Magmatism is induced by hot uprising diapirs originating in the top of the lower mantle. The diapirs induce convective circulation within the upper mantle when the lower mantle is rather cold but induce flushing event, that is, a massive flow across the 660-km phase boundary and the resulting vigorous magmatism, when the lower mantle becomes sufficiently hot owing to the internal heating. When the viscosity contrast is moderate, the fluid in the coldest part of top TBL behaves as a moving lid. Both the moving lid and hot uprising diapirs induce magmatic activity; the magmatic activity due to a moving lid resembles ridge volcanism. The mantle of Venus and that of the early Earth are suggested to have been on the regime modeled here, and the magmatic activity by flushing event is compared to the magmatism of volcanic plain formation on Venus.

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“…This thin crustal layer may thicken appreciably with long-lived subduction into the high-viscosity lower mantle 29 . Furthermore, it has been argued that basalt may be near its solidus in the uppermost and lowermost parts of the lower mantle 30 . Thus the anisotropy may be due to the preferred alignment of melt inclusions (a mechanism which generates anisotropy very effectively 4 ), which results from shear deformation at the`660'.…”

mentioning

confidence: 99%

Mid-mantle deformation inferred from seismic anisotropy

Wookey

Kendall

Barruol

2002

Nature

160

137

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Article:Wookey, J., Kendall, J.M. and Barruol, G. (2002) Mid-mantle deformation inferred from seismic anisotropy. Nature, 415 (6873 777changed uniformly by +5 K, -10 K or -20 K. Additional experiments, not presented here, demonstrated insensitivity of the simulated heat¯uxes to changes in surface¯uxes of heat, moisture and momentum, or in scale-selective dissipation.Except as noted below, all quantities used to create Figs 1±3 are zonal means, averaged over the mid-latitude region de®ned as 1,000±200 mbar, 288±688 latitude, for each hemisphere. The results were found to be insensitive to variations in the de®nition of the mid-latitude region. In particular, this height is suf®cient to include essentially the whole troposphere and all the eddy activity. It should be noted that the average meridional temperature gradient is closely constrained by the ®xed surface temperatures, and could be replaced by the surface temperature gradient in the calculations with only a modest loss in accuracy. The diabatic forcing term q includes both the radiative heating averaged over the mid-latitude region and the surface¯uxes of sensible heat, although the contribution of surface¯uxes turns out to be small. The height scales H and H s , used to calculate the radius of deformation L D , and the Charney length scale L g , were taken to be constant at 8 km as they did not vary substantially in any of the experiments. In calculating L g , the vertical averages were weighted 13 by a factor e 2z=D , where D H s = 0:48 1:48g . The latitude of the zonal wind maximum, which did not vary substantially between experiments, was used to calculate f and b. The size of the baroclinic zone, L zone , was de®ned as the distance between the two latitudes where the strength of the vertically averaged zonal-mean zonal wind ®rst drops to half of its maximum value. In all calculations the correlation coef®cient k was given a constant value of 0.25, while the utilization coef®cient e was given a constant value of 0.75.

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The fate of subducted basaltic crust in the Earth's lower mantle

Cited by 377 publications

References 23 publications

Electronic and magnetic structures of the postperovskite-type Fe ₂ O ₃ and implications for planetary magnetic records and deep interiors

Electronic and magnetic structures of the postperovskite-type Fe ₂ O ₃ and implications for planetary magnetic records and deep interiors

Numerical models of magmatism in convecting mantle with temperature‐dependent viscosity and their implications for Venus and Earth

Mid-mantle deformation inferred from seismic anisotropy

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The fate of subducted basaltic crust in the Earth's lower mantle

Cited by 377 publications

References 23 publications

Electronic and magnetic structures of the postperovskite-type Fe 2 O 3 and implications for planetary magnetic records and deep interiors

Electronic and magnetic structures of the postperovskite-type Fe 2 O 3 and implications for planetary magnetic records and deep interiors

Numerical models of magmatism in convecting mantle with temperature‐dependent viscosity and their implications for Venus and Earth

Mid-mantle deformation inferred from seismic anisotropy

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Product

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Electronic and magnetic structures of the postperovskite-type Fe ₂ O ₃ and implications for planetary magnetic records and deep interiors

Electronic and magnetic structures of the postperovskite-type Fe ₂ O ₃ and implications for planetary magnetic records and deep interiors