TY - JOUR

T1 - Phase Relations in the Harzburgite–Hydrous Carbonate Melt at 5.5–7.5 GPa and 1200–1350°С

AU - Kruk, A. N.

AU - Sokol, A. G.

AU - Palyanov, Yu N.

PY - 2018/11/1

Y1 - 2018/11/1

N2 - 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 Xco2 = 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 Xco2 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/m2, 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 CO2 accumulation in subcratonic lithosphere.

AB - 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 Xco2 = 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 Xco2 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/m2, 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 CO2 accumulation in subcratonic lithosphere.

KW - kimberlite

KW - magnesite

KW - mantle

KW - metasomatism

KW - LHERZOLITE

KW - LITHOSPHERIC MANTLE

KW - DIAMOND

KW - CACO3-MGCO3

KW - GROUP-II KIMBERLITES

KW - MECHANISMS

KW - MAGMAS

KW - CONSTRAINTS

KW - UDACHNAYA PERIDOTITE XENOLITHS

KW - METASOMATISM

UR - http://www.scopus.com/inward/record.url?scp=85056088386&partnerID=8YFLogxK

U2 - 10.1134/S0869591118060036

DO - 10.1134/S0869591118060036

M3 - Article

AN - SCOPUS:85056088386

VL - 26

SP - 575

EP - 587

JO - Petrology

JF - Petrology

SN - 0869-5911

IS - 6

ER -