Phase relations in the phlogopite-apatite system at 20 kbar; implications for the role of fluorine in mantle melting

Article Abstract:

The presence of fluorine (F) between phlogopite, apatite and melt under mantle conditions is determined by examining phase relations at 20kb in the simple, Fe, Ti-free systems hydroxyphlogopite-hydroxyapatite and hydroxyfluorphlogopite-hydroxyfluorapatite. It is revealed that during partial melting in the mantle, F is likely to remain in the solid phases and not in the melt, and therefore the enrichment of fluorine in ultrapotassic magmas and its role in their evolution are restricted. The first melts that are formed in the presence of F may contain more P2O2 than those formed in the absence of F. This is revealed by the difference in the minimum melting composition in the F-absent and F-bearing systems.

Influence, Earth, Mantle (Geology)

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An experimental study of partitioning of fluorine between K-richterite, apatite, phlogopite, and melt at 20 kbar

Article Abstract:

A study of the distribution of fluorine (F) between phlogopite, apatite, K-richterite and melt, at 20 kbar in mantle compositions, reveals that F is in solid phase during partial melting and enters the solid during crystallization. During melting, the existence of P2O5 increases the K-enriched melts. Changes in bulk compositions of the end-member minerals, pressure and temperature affect the compositions of the F-bearing phases. Amount of F is largest in phlogopite and smallest in K-richterite.

Observations, Minerals, Minerals (Geology), Analytic geochemistry

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Partitioning of fluorine and chlorine between biotite and granitic melt: experimental calbration at 200 MPa H2O

Article Abstract:

The effects of magnesium on the partitioning of fluorine and chlorine between biotite and melt were analyzed in a natural F-rich vitrophyric rhyolite from Spro Mountain, UT. Spectroscopic analysis of the Spor Mountain rhyolite indicated the presence of glass and biotite laths with fluorite, quartz and zircon. The presence of magnesium in the sample modulated halogen partitioning due to the reequilibration of degassed magma.

Chlorine, Petrology, Granite, Biotite

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