TY - JOUR

T1 - The Mg-carbonate–Fe interaction: 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 - Publisher Copyright: © 2019 China University of Geosciences (Beijing) and Peking University

PY - 2019/7/1

Y1 - 2019/7/1

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: 6 MgCO3 + 19 Fe = 8 FeO +10 (Mg0.6Fe0.4)O + Fe7C3 + 3 C. 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: 6 MgCO3 + 19 Fe = 8 FeO +10 (Mg0.6Fe0.4)O + Fe7C3 + 3 C. 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

KW - SYSTEM

KW - HIGH-PRESSURE

KW - DEEP LOWER MANTLE

KW - EARTHS MANTLE

KW - IRON-CARBIDE

KW - STABILITY

KW - DIFFRACTION DATA

KW - EQUATION-OF-STATE

KW - TRANSITION ZONE

KW - PHASE-RELATIONS

UR - http://www.scopus.com/inward/record.url?scp=85055743906&partnerID=8YFLogxK

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 -