Phase Relations in the Harzburgite–Hydrous Carbonate Melt at 5.5–7.5 GPa and 1200–1350°С

Phase relations are studied experimentally in the harzburgite–hydrous carbonate melt system, the bulk composition of which represents primary kimberlite. Experiments were carried out at 5.5 and 7.5 GPa, 1200–1350°С, and = 0.39–0.57, and lasted 60 hours. It is established that olivine–orthopyroxene–g...

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Bibliographic Details
Published in:Petrology 2018-11, Vol.26 (6), p.575-587
Main Authors: Kruk, A. N., Sokol, A. G., Palyanov, Yu. N.
Format: Article
Language:English
Subjects:
Asthenosphere
Biotite
Carbon dioxide
Carbonates
Composition
Crystallization
Data processing
Earth and Environmental Science
Earth Sciences
Garnet
Geochemistry
Heat flux
Heat transfer
High temperature
Lithosphere
Magma
Magnesite
Magnesium carbonate
Melts
Mineralogy
Olivine
Peridotite
Silicates
Temperature
Temperature effects
Temperature range
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Summary:Phase relations are studied experimentally in the harzburgite–hydrous carbonate melt system, the bulk composition of which represents primary kimberlite. Experiments were carried out at 5.5 and 7.5 GPa, 1200–1350°С, and = 0.39–0.57, and lasted 60 hours. It is established that olivine–orthopyroxene–garnet–magnesite–melt assemblage is stable within the entire range of the studied parameters. With increase of temperature and in the system, Ca# in the melt and the olivine fraction in the peridotite matrix significantly decrease. The composition of silicate phases in run products is close to those of high-temperature mantle peridotite. Analysis of obtained data suggest that magnesite at the base of subcontinental lithosphere could be derived by metasomatic alteration of peridotite by asthenospheric hydrous carbonate melts. The process is possible in the temperature range typical of heat flux of 40–45 mW/m 2 , which corresponds to the conditions of formation of the deepest peridotite xenoliths. Crystallization of magnesite during interaction with peridotite matrix can be considered as experimentally substantiated mechanism of CO 2 accumulation in subcratonic lithosphere.
ISSN:0869-5911
1556-2085
DOI:10.1134/S0869591118060036