Phase relations of phlogopite and pyroxene with magnesite from 4 to 8 GPa: KCMAS–H2O and KCMAS–H2O–CO2 - MacEwan Users Only

Enggist, A., & Luth, R. (2016). Phase relations of phlogopite and pyroxene with magnesite from 4 to 8 GPa: KCMAS–H2O and KCMAS–H2O–CO2.
Metadata
TitlePhase relations of phlogopite and pyroxene with magnesite from 4 to 8 GPa: KCMAS–H2O and KCMAS–H2O–CO2
Author(s)Enggist, Andreas; Luth, Robert
Date2016
Keyword(s)experimental petrology, melting metasomatism, fluid, potassium, carbon cycling, phlogopite, richterite
DescriptionTo constrain the melting phase relationships of phlogopite and magnesite in the presence of clino- and orthopyroxene, we performed experiments in the K2O–CaO–MgO–Al2O3–SiO2–H2O (KCMAS–H2O) and K2O–CaO–MgO–Al2O3–SiO2–H2O–CO2 (KCMAS–H2O–CO2) systems at pressures of 4–8 GPa and temperatures from 1100 to 1600 °C. We bracketed the carbonate-free solidus between 1250 and 1300 °C at 4 and 5 GPa, and between 1300 and 1350 °C at 6, 7 and 8 GPa. The carbonate-bearing solidus was bracketed between 1150 and 1200 °C at 4, 5 and 6 GPa, and between 1100 and 1150 °C at 7 and 8 GPa. Below the solidus in both systems at 4–6 GPa, phlogopite is in equilibrium with enstatite, diopside, garnet (plus magnesite in the carbonate-bearing system) and a fluid. At 7 GPa, phlogopite coexists with KK-richterite, enstatite, diopside, garnet (plus magnesite in the carbonate-bearing system) and a fluid. KK-richterite is the only stable K-bearing phase at 8 GPa and coexists with enstatite, diopside, garnet (plus magnesite in the carbonate-bearing system) and a fluid. In KCMAS–H2O, phlogopite is present to ~100 °C above the solidus. Olivine forms at the solidus and coexists with enstatite, diopside, garnet and melt. At depth in a subcontinental lithospheric mantle keel, phlogopite would be stable with orthopyroxene, clinopyroxene and magnesite to ~5 GPa along a 40 mW/m2 geotherm. A hydrous, potassic and CO2-bearing melt that intrudes the subcontinental mantle can react with olivine, enstatite and garnet, crystallizing phlogopite, magnesite and potentially liberating a hydrous fluid.
Peer ReviewedYes
Type of ItemJournal Articles
DOI10.1007/s00410-016-1304-2
Publication InformationEnggist, A., & Luth, R. W. (2016). Contributions to Mineralogy and Petrology, 171, 88. doi:10.1007/s00410-016-1304-2
MacEwan Users Onlyhttps://library.macewan.ca/cgi-bin/SFX/url.pl/8S6
LanguageEnglish
RightsAll Rights Reserved