TY - JOUR

T1 - The reactions between iron and magnesite at 6 GPa and 1273-1873 K

T2 - Implication to reduction of subducted carbonate in the deep mantle

AU - Martirosyan, Naira S.

AU - Litasov, Konstantin D.

AU - Shatskiy, Anton

AU - Ohtani, Eiji

PY - 2015

Y1 - 2015

N2 - The interaction between Fe-metal and magnesite was studied in multianvil experiments at 6 GPa and 1273-1873 K using different capsule materials: Fe, BN, and MgO. It was observed that at subsolidus conditions reaction proceeds with the formation of Fe3C and magnesiowüstite in the stoichiometric proportions according to relation: MgCO3 + 5Fe = 3(Fe0.66Mg0.33)O + Fe3C. At melting conditions (1673-1873 K) magnesite and iron react in nearly equivalent molar proportions with formation of Mg-Fe-carbonatite melt, Fe-C alloy, magnesiowüstite and graphite. The reactions clearly show that free carbon and metallic iron phases cannot coexist in the upper mantle and presumably in transition zone and will always form Fe-carbide. The carbon content in Fe-C alloy and its coexistence with diamond will be strongly dependent on the oxygen fugacity. The studied reactions can be considered as intermediate processes in the reduced mantle domains at the contact with submerging subduction slabs and have further implication to the processes at the core-mantle boundary.

AB - The interaction between Fe-metal and magnesite was studied in multianvil experiments at 6 GPa and 1273-1873 K using different capsule materials: Fe, BN, and MgO. It was observed that at subsolidus conditions reaction proceeds with the formation of Fe3C and magnesiowüstite in the stoichiometric proportions according to relation: MgCO3 + 5Fe = 3(Fe0.66Mg0.33)O + Fe3C. At melting conditions (1673-1873 K) magnesite and iron react in nearly equivalent molar proportions with formation of Mg-Fe-carbonatite melt, Fe-C alloy, magnesiowüstite and graphite. The reactions clearly show that free carbon and metallic iron phases cannot coexist in the upper mantle and presumably in transition zone and will always form Fe-carbide. The carbon content in Fe-C alloy and its coexistence with diamond will be strongly dependent on the oxygen fugacity. The studied reactions can be considered as intermediate processes in the reduced mantle domains at the contact with submerging subduction slabs and have further implication to the processes at the core-mantle boundary.

KW - Carbonate

KW - High-pressure experiment

KW - Iron

KW - Mantle

KW - Subduction

UR - http://www.scopus.com/inward/record.url?scp=84928894242&partnerID=8YFLogxK

U2 - 10.2465/jmps.141003a

DO - 10.2465/jmps.141003a

M3 - Article

AN - SCOPUS:84928894242

VL - 110

SP - 49

EP - 59

JO - Journal of Mineralogical and Petrological Sciences

JF - Journal of Mineralogical and Petrological Sciences

SN - 1345-6296

IS - 2

ER -