Spinel assemblages in lunar meteorites Graves Nunataks 06157 and Dhofar 1528: Implications for impact melting and equilibration in the Moon's upper mantle

2018 ◽  
Vol 54 (2) ◽  
pp. 379-394 ◽  
Author(s):  
Axel Wittmann ◽  
Randy L. Korotev ◽  
Bradley L. Jolliff ◽  
Paul K. Carpenter
Keyword(s):  
Upper Mantle ◽  
Lunar Meteorites

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>

HYPOTHETICAL TECTONIC EVOLUTION OF THE LASAL MOUNTAINS AND THE UNCOMPAHGRE PLATEAU BASED ON UPPER MANTLE TOMOGRAPHY

2016 ◽  
Author(s):  
Verner C. Johnson ◽  
◽  
Joseph Michael Mazza ◽  
Adam L. Trumbo ◽  
Michael Feil ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Tectonic Evolution ◽  
Uncompahgre Plateau
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