Adiabatic temperature profile in the mantle

Katsura, Tomoo; Yoneda, Akira; Yamazaki, Daisuke; Yoshino, Takashi; Ito, Eiji

doi:10.1016/j.pepi.2010.07.001

Cited by 408 publications

(393 citation statements)

References 42 publications

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“…in the majority of the lower mantle. Furthermore, the ambient lower mantle temperatures (Katsura et al, 2010) are too high for hydrous minerals (Walter et al, 2015), therefore, we conclude that the majority of lower mantle is dry. Shcheka and Keppler (2012) showed that MgSiO 3 bridgmanite contained ~1 wt.…”

Section: Geochemical Implicationsmentioning

confidence: 77%

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: 77%

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Liu¹,

Ishii²,

Katsura³

2017

Geochem. Persp. Let.

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“…Carbonatite melts are at least 2 orders of magnitude more conductive than silicate melts [Gaillard et al, 2008;Yoshino et al, 2010]. Carbonatite melts can form in trace amounts deep in the mantle [Dasgupta and Hirschmann, 2006] and are thought to be stable in the upper asthenosphere beneath seafloor older than about 45 Ma [Hirschmann, 2010].…”

Section: Mantle Conductivity: a Summarymentioning

confidence: 99%

Geophysical and petrological constraints on ocean plate dynamics

Sarafian¹

2017

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This thesis investigates the formation and subsequent motion of oceanic lithospheric plates through geophysical and petrological methods. Ocean crust and lithosphere forms at mid-ocean ridges as the underlying asthenosphere rises, melts, and flows away from the ridge axis. In Chapters 2 and 3, I present the results from partial melting experiments of mantle peridotite that were conducted in order to examine the mantle melting point, or solidus, beneath a mid-ocean ridge. Chapter 2 determines the peridotite solidus at a single pressure of 1.5 GPa and concludes that the oceanic mantle potential temperature must be ~60 ºC hotter than current estimates. Chapter 3 goes further to provide a more accurate parameterization of the anhydrous mantle solidus from experiments over a range of pressures. This chapter concludes that the range of potential temperatures of the mantle beneath mid-ocean ridges and plumes is smaller than currently estimated. Once formed, the oceanic plate moves atop the underlying asthenosphere away from the ridge axis. Chapter 4 uses seafloor magnetotelluric data to investigate the mechanism responsible for plate motion at the lithosphere-asthenosphere boundary. The resulting two dimensional conductivity model shows a simple layered structure. By applying petrological constraints, I conclude that the upper asthenosphere does not contain substantial melt, which suggests that either a thermal or hydration mechanism supports plate motion. Oceanic plate motion has dramatically changed the surface of the Earth over time, and evidence for ancient plate motion is obvious from detailed studies of the longer lived continental lithosphere. In Chapter 5, I investigate past plate motion by inverting magnetotelluric data collected over eastern Zambia. The conductivity model probes the Zambian lithosphere and reveals an ancient subduction zone previously suspected from surface studies. This chapter elucidates the complex lithospheric structure of eastern Zambia and the geometry of the tectonic elements in the region, which collided as a result of past oceanic plate motion. Combined, the chapters of this thesis provide critical constraints on ocean plate dynamics.

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“…The adiabatic temperature profile in the mantle, based on experiments and the use of the equation of state of MgO from various sources, was calculated by Katsura et al (2010). The adiabatic temperature coefficient in the lower mantle was found to be 0.3 K/km (lower than in the upper mantle), and the adiabatic temperature at a depth of 2,700 km was estimated at 2,730 ± 50 K, if convective heat still dominates in this region.…”

Section: Formation Of Carbonatitic Partial Melts In the Lowermost Mantlementioning

confidence: 99%

A primary natrocarbonatitic association in the Deep Earth

2015

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In addition to ultramafic and mafic associations, a primary natrocarbonatitic association occurs in the lower mantle. To date, it was identified as inclusions in diamonds from the Juina area, Mato Grosso State, Brazil. It comprises almost 50 mineral species: carbonates, halides, fluorides, phosphates, sulfates, oxides, silicates, sulfides and native elements. In addition, volatiles are present in this association. Among oxides, coexisting periclase and wüstite were identified, pointing to the formation of the natrocarbonatitic association at a depth greater than 2,000 km. Some ironrich (Mg,Fe)O inclusions in diamond are attributed to the lowermost mantle. The initial lower-mantle carbonatitic melt formed as a result of low-fraction partial melting of carbon-containing lower-mantle material, rich in P, F, Cl and other volatile elements, at the core-mantle boundary. During ascent to the surface, the initial carbonatitic melt dissociated into two immiscible parts, a carbonate-silicate and a chloride-carbonate melt. The latter melt is parental to the natrocarbonatitic lower-mantle association. Diamonds with carbonatitic inclusions were formed in carbonatitic melts or high-density fluids.

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Adiabatic temperature profile in the mantle

Cited by 408 publications

References 42 publications

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Rapid decrease of MgAlO2.5 component in bridgmanite with pressure

Geophysical and petrological constraints on ocean plate dynamics

A primary natrocarbonatitic association in the Deep Earth

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