TY - JOUR
T1 - The Mg-carbonate–Fe interaction
T2 - Implication for the fate of subducted carbonates and formation of diamond in the lower mantle
AU - Martirosyan, Naira S.
AU - Litasov, Konstantin D.
AU - Lobanov, Sergey S.
AU - Goncharov, Alexander F.
AU - Shatskiy, Anton
AU - Ohfuji, Hiroaki
AU - Prakapenka, Vitali
N1 - Funding Information:
We thank three anonymous reviewers for critical comments and I. Safonova for editorial handling. This work was supported by Russian Science Foundation , project No and 17-17-01177. AG and SL acknowledge the support of the Deep Carbon Observatory through the Alfred P. Sloan Foundation.
Publisher Copyright:
© 2019 China University of Geosciences (Beijing) and Peking University
PY - 2019/7
Y1 - 2019/7
N2 - The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe0 system at 70–150 GPa and 800–2600 K in a laser-heated diamond anvil cell. Using in situ synchrotron X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by: 6MgCO3 + 19Fe = 8FeO +10(Mg0.6Fe0.4)O + Fe7C3 + 3C. The presented results suggest that the interaction of carbonates with Fe0 or Fe0-bearing rocks can produce Fe-carbide and diamond, which can accumulate in the D’’ region, depending on its carbon to Fe ratio. Due to the sluggish kinetics of the transformation, diamond can remain metastable at the core-mantle boundary (CMB) unless it is in a direct contact with Fe-metal. In addition, it can be remobilized by redox melting accompanying the generation of mantle plumes.
AB - The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe0 system at 70–150 GPa and 800–2600 K in a laser-heated diamond anvil cell. Using in situ synchrotron X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by: 6MgCO3 + 19Fe = 8FeO +10(Mg0.6Fe0.4)O + Fe7C3 + 3C. The presented results suggest that the interaction of carbonates with Fe0 or Fe0-bearing rocks can produce Fe-carbide and diamond, which can accumulate in the D’’ region, depending on its carbon to Fe ratio. Due to the sluggish kinetics of the transformation, diamond can remain metastable at the core-mantle boundary (CMB) unless it is in a direct contact with Fe-metal. In addition, it can be remobilized by redox melting accompanying the generation of mantle plumes.
KW - Carbide
KW - Carbonate
KW - Deep carbon cycle
KW - High pressure
KW - Iron
KW - Redox reaction
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U2 - 10.1016/j.gsf.2018.10.003
DO - 10.1016/j.gsf.2018.10.003
M3 - Article
AN - SCOPUS:85055743906
VL - 10
SP - 1449
EP - 1458
JO - Geoscience Frontiers
JF - Geoscience Frontiers
SN - 1674-9871
IS - 4
ER -