Results 121 to 130 of about 4,719 (167)

Redox control during mantle/melt interaction

Geochimica et Cosmochimica Acta, 1992
We have investigated redox systematics in the upper mantle under continents and ocean islands, using data on olivine, orthopyroxene, and spinel from both spinel lherzolites and coexisting pyroxenite xenoliths. Calculated ƒo2 values at 15 kb for continental xenoliths range from QFM−5.3 to QFM+0.8, with median values (M) of QFM−0.5 for volatile-free ...
H.E.F. Amundsen, E.-R. Neumann
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Melt pathways in the mantle

Nature, 1995
OCEANIC ridges are the dominant sites of energy and mass transfer from the Earth's interior to the crust, hydrosphere and atmosphere, but many key processes beneath ridges remain poorly understood. One outstanding problem is how partial melts in the asthenosphere concentrate into channels - initially, melts must leave their source by intergranular ...
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Melt generation by isentropic mantle upwelling

Earth and Planetary Science Letters, 1995
The primary effects of melt segregation processes on isentropic melting paths are studied using a one-dimensional steady-state model. A parameterization of X(T′,P) to 9 GPa shows that X, the degree of melting, depends on pressure, as well as on T′, the homologous temperature.
Hikaru Iwamori, Dan McKenzie, Eiichi Takahashi   +2 more
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Melt Segregation and P-T Path of Mantle Melting

Mineralogical Magazine, 1994
Chemical composition of the mantle which is undergoing melting can change as melt segregation proceeds, which affects the pressure-temperature path of the melting. The effects can be important when fractional-type melting occurs, because the melt is efficiently isolated from the residue in terms of chemical interaction. In this paper we investigate the
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Mantle metasomatism by ephemeral carbonatite melts

Nature, 1988
Recent experiments1 have shown that, at a range of upper-mantle temperatures and pressures, a carbonatite (carbonate-rich) melt occurs as a very small melt fraction in equilibrium with pargasite lherzolite. This melt has low water content and low TiO2 content, and will be extremely effective in transporting large-ion lithophile elements.
David H. Green, Margaret E. Wallace
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Partial melting in the upper mantle

Physics of the Earth and Planetary Interiors, 1970
The low velocity zone in tectonic and oceanic regions is too pronounced to be the effect of high temperature gradients alone. Partial melting is consistent with the low velocity, low Q and abrupt boundaries of this region of the upper mantle and is also consistent with measured heat flow values.
Anderson, Don L., Sammis, Charles
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Experimental Definition of Mantle Melting and Implications for Mantle Dynamics

Mineralogical Magazine, 1994
The natural sampling of the Earth's Mantle by xenoliths or by magmas gives evidence for the presence of carbon and hydrogen within the upper mantle and extending into the Transition Zone. Models of accretion and studies of subduetion respectively provide arguments for degassing of primitive C-H species from the upper mantle and for re-cycling of ...
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Mantle Convection and Melt Segregation

2001
The Earth began to accrete some 4.5 billion years ago by the accumulation of impacting planetesimals of various sizes. The impacting bodies converted their gravitational and kinetic energies into heat which probably produced initially a large-scale melting condition of the planet. Whether or not the primordial Earth consisted of a gigantic magma ocean,
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Earth’s Mantle Melting and Volcanism

2014
Convection currents inside the Earth’s asthenosphere will cause instability at shallow depths in the mantle. Rising material and subsequent decompression melting will form hot, upwelling mantle plumes or diapirs. This phenomenon is more common on slow spreading ridges (total rate 5 cm/yrs) spreading ridge segments with their extensive fissural ...
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Carbonate melts under lower mantle conditions

Science Bulletin, 2022
Wu M., Jiang J., Tse J.S., Pan Y.
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