Transformations and Decomposition of MnCO3 at Earth's Lower Mantle Conditions

Frontiers in Digital Humanities

Morard, Guillaume²  Stodolna, Julien³  Reagan, Mary M.⁵  Boulard, Eglantine⁵  Koh, Ai L.⁷  Liu, Yijin⁸  Mezouar, Mohamed⁹  Mao, Wendy L.^1,10 

[1] Pierre et Marie Curie, MuséCentre National de la Recherche Scientifique, UMR Centre National de la Recherche Scientifique 7590, Institut de MinéEDF Lab Les Renardieres, Dpt MMC, Moret sur Loing, France;European Synchrotron Radiation Facility (ESRF), Grenoble, France;Geological Sciences, Stanford University, Stanford, CA, USA;Histoire Naturelle, Paris, France;Stanford Nano Shared Facilities, Stanford University, Stanford, CA, USA;Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA;ralogie, de Physique des Matériaux et de Cosmochimie, IRD, Sorbonne Universités—Universitéum National d'

关键词: Carbonate;    Phase Transition;    Redox reaction;    Deep carbon cycle;    high pressure;   

DOI  :  10.3389/feart.2016.00107

学科分类：社会科学、人文和艺术（综合）

来源: Frontiers

【 摘 要 】

Carbonates have been proposed as the principal oxidized carbon-bearing phases in the Earth’s interior. Their phase diagram for the high pressure and temperature conditions of the mantle can provide crucial constraints on the deep carbon cycle. We investigated the behavior of MnCO3 at pressures up to 75 GPa and temperatures up to 2200 K. The phase assemblage in the resulting run products was determined in situ by X-ray diffraction (XRD), and the recovered samples were studied by analytical transmission electron microscopy (TEM) and X-ray absorption near edge structure (XANES) imaging. At moderate temperatures below 1400 K and pressures above 50 GPa, MnCO3 transformed into the MnCO3-II phase, with XANES data indicating no change in the manganese oxidation state in MnCO3-II. However, upon heating above 1400 K at the same pressure conditions, both MnCO3 and MnCO3-II undergo decomposition and redox reactions which lead to the formation of manganese oxides and reduced carbon.

【 授权许可】

CC BY