Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity

Fukao, Yoshio; Obayashi, Masayuki

doi:10.1002/2013jb010466

Cited by 476 publications

(508 citation statements)

References 78 publications

(100 reference statements)

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“…%; Irifune, 1994), dominates the viscosity of this region (Girard et al, 2016). Seismic observation suggests that some slabs stagnate at 600-1000 km depths (Fukao and Obayashi, 2013). Since there are no phase transitions in this region, some special explanations are required.…”

Section: Geochemical Implicationsmentioning

confidence: 98%

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Liu¹,

Ishii²,

Katsura³

2017

Geochem. Persp. Let.

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The solubility of the MgAlO 2.5 component in bridgmanite was measured at pressures of 27, 35 and 40 GPa and a temperature of 2000 o K using an ultra-high pressure multi-anvil press. Compositional analysis of recovered samples demonstrated that the MgAlO 2.5 component decreases with increasing pressure, and approaches virtually zero at 40 GPa. Above this pressure, the MgAlO 2.5 component, i.e. the oxygen-vacancy substitution, becomes negligible, and Al is incorporated in bridgmanite by the charge-coupled substitution only. These results are supported by the volume change associated with the change from the oxygen-vacancy substitution to charge-coupled substitution. The present result may explain the seismically observed slab stagnation in the mid-lower mantle. Although bridgmanite has been put forward as a potential host for water and argon in the lower mantle by trapping them in oxygen vacancies, such capabilities will rapidly decrease with depth and be lost in regions deeper than 1000 km.

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Section: Geochemical Implicationsmentioning

confidence: 98%

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Liu¹,

Ishii²,

Katsura³

2017

Geochem. Persp. Let.

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“…The plumes also rise in a nearly vertical fashion from the CMB, not what would be expected if vigorous convection of the lower mantle were present (see Hand, 2015). Indeed, there had already been evidence that descending lithospheric slabs stall out near the 1000 km depth (Fukao et al, 2013). Lastly, pinching and shearing in the plumes as they reached the 1000 km depth suggested that the plumes are thermochemical plumes, i.e., composed of different material than the surrounding mantle (for a discussion of thermochemical plumes, see Kumagai et al, 2008).…”

Section: Earthquakes and Mantle Plumes In Earth Expansionmentioning

confidence: 96%

Indications from space geodesy, gravimetry and seismology for slow Earth expansion at present – comment on “The Earth expansion theory and its transition from scientific hypothesis to pseudoscientific belief” by Sudiro (2014)

Edwards

2016

Hist. Geo Space. Sci.

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Abstract. In a recent article in this journal, Paolo Sudiro (2014) considered the long history of the expanding Earth theory and its recent descent into what he termed "pseudoscientific belief". The expanding Earth theory contends that the radius of the Earth was once one-half to two-thirds of its current value, with the Earth's continents forming a continuous sialic cover over the Earth. The theory has had two main variants: slow expansion at about 0.5 mm yr −1 radial increase since the time of Earth's formation and fast expansion at about 5 mm yr −1 since the Triassic. Focusing on Maxlow's model, Sudiro thoroughly addresses the possibly insurmountable difficulties of the fast version, such as an improbably high density and surface gravity prior to 200 Ma. He omits, however, any discussion of the slow expansion model, which has a longer history and far fewer theoretical difficulties. Moreover, recent evidence from space geodesy, gravimetry and seismology indicates that the Earth at present may be slowly expanding at 0.1-0.4 mm yr −1 . It is concluded that Sudiro's obituary of the expanding Earth theory as a whole must be considered premature at this time.

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“…Yoshida and Hamano 2015 , Yoshida, 20141 1970Forsyth and Uyeda, 1975, Gerya, 2011Forsyth and Uyeda 1975 P 660 km 1000 km Fukao and Obayashi, 2013660 km , Fukao et al, 2009Yoshioka and Naganoda, 2010Yoshida, 2013Alvarez, 1982, 1990 …”

Section: Yoshida and Hamano 2015mentioning

confidence: 99%

プレート運動と大陸移動の原動力－再考

Yoshida

2015

Jour. Geol. Soc. Japan

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The establishment of the theory of plate tectonics at the end of the s provoked quantitative discussions regarding the forces acting on lithospheric plates. Subsequent studies during the early-to mids considered plate motions as rigid rotations on a spherical surface. A theoretical analysis based only on tectonic information from the Earth s surface revealed that a candidate for the primal driving force of plate motion was slab pull , which may be balanced almost completely by slab resistance . However, because plate interiors of the real Earth have finite effective viscosity and are part of the cold thermal boundary layers involved in mantle convection, they should move with an element of internal deformation rather than perfectly rigid motion. A recent numerical simulation of -D spherical mantle convection revealed that the breakup of Pangea, subsequent continental drift, and the present-day continental distribution, could be acheived by planetary-scale mantle flow. Large-scale lateral mantle flow is inferred to have originated from a high-temperature anomaly region beneath Pangea due to a supercontinental thermal insulation effect, rather than by mantle upwelling flow from a superplume , and subduction of cold boundary layers is inferred to have spontaneously developed in the North Tethys Ocean during the early stages of the breakup of Pangea. The present results, combined with other numerical simulation results and seismological evidence from a recent sub-seafloor structure survey, indicate that the (continental) mantle drag force , enhanced by mantle flow beneath the continental/oceanic plates, could be the primal driving force of plate motion and continental drift. This possibility raises new questions about whether the slab-pull force or mantle-drag force is the primal driving force for plate motion and continental drift.

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Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity

Cited by 476 publications

References 78 publications

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Indications from space geodesy, gravimetry and seismology for slow Earth expansion at present – comment on “The Earth expansion theory and its transition from scientific hypothesis to pseudoscientific belief” by Sudiro (2014)

プレート運動と大陸移動の原動力－再考

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