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Title: Carbonate stability in the reduced lower mantle

Carbonate minerals are important hosts of carbon in the crust and mantle with a key role in the transport and storage of carbon in Earth’s deep interior over the history of the planet. Whether subducted carbonates efficiently melt and break down due to interactions with reduced phases or are preserved to great depths and ultimately reach the core-mantle boundary remains controversial. In this study, experiments in the laser-heated diamond anvil cell (LHDAC) on layered samples of dolomite (Mg,Ca)CO3 and iron at pressure and temperature conditions reaching those of the deep lower mantle show that carbon-iron redox interactions destabilize the MgCO3 component, producing a mixture of diamond, Fe7C3, and (Mg,Fe)O. However, CaCO3 is preserved, supporting its relative stability in carbonate-rich lithologies under reducing lower mantle conditions. These results constrain the thermodynamic stability of redox-driven breakdown of carbonates and demonstrate progress towards multiphase mantle petrology in the LHDAC at conditions of the lowermost mantle.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [3]
  1. Ecole Polytechnique Federale Lausanne (Switzlerland); Michigan State Univ., East Lansing, MI (United States)
  2. Ecole Polytechnique Federale Lausanne (Switzlerland); Sorbonne Paris Cite (France)
  3. Ecole Polytechnique Federale Lausanne (Switzlerland)
  4. Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
Publication Date:
Grant/Contract Number:
FG02-94ER14466
Type:
Accepted Manuscript
Journal Name:
Earth and Planetary Science Letters
Additional Journal Information:
Journal Volume: 489; Journal Issue: C; Journal ID: ISSN 0012-821X
Publisher:
Elsevier
Research Org:
GeoSoilEnviroCARS, University of Chicago
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES
OSTI Identifier:
1426861

Dorfman, Susannah M., Badro, James, Nabiei, Farhang, Prakapenka, Vitali B., Cantoni, Marco, and Gillet, Philippe. Carbonate stability in the reduced lower mantle. United States: N. p., Web. doi:10.1016/j.epsl.2018.02.035.
Dorfman, Susannah M., Badro, James, Nabiei, Farhang, Prakapenka, Vitali B., Cantoni, Marco, & Gillet, Philippe. Carbonate stability in the reduced lower mantle. United States. doi:10.1016/j.epsl.2018.02.035.
Dorfman, Susannah M., Badro, James, Nabiei, Farhang, Prakapenka, Vitali B., Cantoni, Marco, and Gillet, Philippe. 2018. "Carbonate stability in the reduced lower mantle". United States. doi:10.1016/j.epsl.2018.02.035.
@article{osti_1426861,
title = {Carbonate stability in the reduced lower mantle},
author = {Dorfman, Susannah M. and Badro, James and Nabiei, Farhang and Prakapenka, Vitali B. and Cantoni, Marco and Gillet, Philippe},
abstractNote = {Carbonate minerals are important hosts of carbon in the crust and mantle with a key role in the transport and storage of carbon in Earth’s deep interior over the history of the planet. Whether subducted carbonates efficiently melt and break down due to interactions with reduced phases or are preserved to great depths and ultimately reach the core-mantle boundary remains controversial. In this study, experiments in the laser-heated diamond anvil cell (LHDAC) on layered samples of dolomite (Mg,Ca)CO3 and iron at pressure and temperature conditions reaching those of the deep lower mantle show that carbon-iron redox interactions destabilize the MgCO3 component, producing a mixture of diamond, Fe7C3, and (Mg,Fe)O. However, CaCO3 is preserved, supporting its relative stability in carbonate-rich lithologies under reducing lower mantle conditions. These results constrain the thermodynamic stability of redox-driven breakdown of carbonates and demonstrate progress towards multiphase mantle petrology in the LHDAC at conditions of the lowermost mantle.},
doi = {10.1016/j.epsl.2018.02.035},
journal = {Earth and Planetary Science Letters},
number = C,
volume = 489,
place = {United States},
year = {2018},
month = {5}
}