scholarly journals Upper Mantle Melt Distribution From Petrologically Constrained Magnetotellurics

2019 ◽  
Vol 20 (7) ◽  
pp. 3328-3346 ◽  
Author(s):  
K. Selway ◽  
J. P. O'Donnell ◽  
Sinan Özaydin
Keyword(s):  
Upper Mantle ◽  
Melt Distribution

Partial melting under spreading ridges

1978 ◽  
Vol 288 (1355) ◽  
pp. 501-525 ◽  
Keyword(s):  
Partial Melting ◽  
Upper Mantle ◽  
Thermal Evolution ◽  
Depth Interval ◽  
Ridge Axis ◽  
Eruption Rate ◽  
Ridge Crest ◽  
Spreading Ridges ◽  
Melt Distribution ◽  
Basalt Composition

Factors of importance in partial melting calculations are discussed. The thermal evolution of a geochemical and petrological model of the upwelling asthenosphere beneath a ridge crest is studied numerically. Partial melting, basalt eruption and differentiation of the upwelling asthenosphere is modelled. Melt distribution and density distribution in the top 100 km of the upper mantle are calculated. Partial melting takes place in a depth interval of 25—60 km below the ridge crest. The degree of partial melting is somewhat less than 20 %. About 2.5 times more liquid is produced by partial melting in the upwelling asthenosphere than is erupted at the ridge centre. This excess liquid solidifies in the lithosphere, off-ridge axis below the Moho. The calculated results are in agreement with the observations on the oceanic ridge basalt composition, its average eruption rate, and geochemical estimates of the degree of partial melting in the sub-ridge upper mantle.

scholarly journals Unravelling (CO2+H2O)-bearing melt distribution in the upper mantle using experimental nano-petrology

2021 ◽  
Author(s):  
Emmanuel Gardés ◽  
Mickael Laumonier ◽  
Fabrice Gaillard ◽  
Malcolm Massuyeau
Keyword(s):  
Upper Mantle ◽  
Melt Distribution

Water Gas May Not Shift in Deep Earth

2020 ◽  
Author(s):  
Nore Stolte ◽  
Junting Yu ◽  
Zixin Chen ◽  
Dimitri A. Sverjensky ◽  
Ding Pan
Keyword(s):  
Formic Acid ◽  
Upper Mantle ◽  
Free Energy Calculations ◽  
Water Gas Shift ◽  
Ab Initio Molecular Dynamics ◽  
Water Gas Shift Reaction ◽  
Carbon Carrier ◽  
Deep Earth ◽  
Shift Reaction ◽  
Water Gas

The water-gas shift reaction is a key reaction in Fischer-Tropsch-type synthesis, which is widely believed to generate hydrocarbons in the deep carbon cycle, but is little known at extreme pressure-temperature conditions found in Earth’s upper mantle. Here, we performed extensive ab initio molecular dynamics simulations and free energy calculations to study the water-gas shift reaction. We found the direct formation of formic acid out of CO and supercritical water at 10∼13 GPa and 1400 K without any catalyst. Contrary to the common assumption that formic acid or formate is an intermediate product, we found that HCOOH is thermodynamically more stable than the products of the water-gas shift reaction above 3 GPa and at 1000∼1400 K. Our study suggests that the water-gas shift reaction may not happen in Earth’s upper mantle, and formic acid or formate may be an important carbon carrier, participating in many geochemical processes in deep Earth.<br>

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