Phlogopite partitioning

Figure 21. Fits of lattice strain model to experimental phlogopite-melt partition coefficients for 1+ and 2+ cations on the large X-site for mn 6+6 of Icenhower and London (1995) at 0.2 GPa and 650°C. 1+ data can be readily fitted 2+ data were fitted by assuming that = lE = 100 GPa. Note that r (x) is slightly larger than rsa, making this site ided for incorporation of Ra. Errors bars, when larger than symbol, are 1 s.d. Ionic radii in Xll-fold coordination are taken from Shaimon (1976).

There are no noble gas partition coefficients for phlogopite. The large size and low mean charge of the large X-site (Zg )) suggest that noble gases could be readily incorporated into phlogopite. 

Foley SF, Jackson SE, Fryer BJ, Greenough JD, Jenner GA (1996) Trace element partition coefficients for clinopyroxene and phlogopite in an alkaline lamprophyre from Newfoundland by LAM-ICP-MS. Geochim Cosmochim Acta 60 629-638... 

Guo J, Green TH (1990) Experimental study of barium partitioning between phlogopite and sihcate liquid at upper-mantle pressure and temperature. Lithos 24 83-96 Harrison WJ, Wood BJ (1980) An experimental investigation of the partitioning of REE between garnet and liquid with reference to the role of defects. Contrib Mineral Petrol 72 145-155 Hart SR, Duim T (1993) Experimental cpx/melt partitioning of 24 trace elements. Contrib Mineral Petrol 113 1-8... 

Schmidt KH, Bottazzi P, Vannucci R, Mengel K (1999) Trace element partitioning between phlogopite, clinopyroxene, and leucite lamproite melt. Earth Planet Sci Lett 168 287-299 Shaimon RD (1976) Revised effetive ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst A32 751-767... 

Although shallow-mantle xenoliths, hosted in alkali basalts, commonly contain C02-rich fluid inclusions (see below), there have been no reports, to the author s knowledge, of H20-rich fluid inclusions in these samples. The C02-rich fluid inclusions are commonly attributed to late, possibly magma-derived, metasomatism of the samples. If such metasomatism was produced by silicate- or carbonate-rich melts, ascent of such a melt could produce saturation in a C02-rich vapor, but H2O would partition strongly into either residual melt or hydrous phases such as phlogopite or amphibole. Thus, the absence of H2O in the fluid inclusions in these samples cannot be taken as evidence that the metasomatic agent was anhydrous. 

Trioctahedral micas, such as phlogopite or biotite, are characterized by four distinct cation lattice sites tetrahedral (Z) sites occupied by silicon and aluminum octahedral (Y) sites, denoted Ml and M2, occupied by Al, Cr, Fe +, Ti, Fe +, Mg, and Mn and a large 12-fold coordinated interlayer X-site occupied by potassium, sodium, calcium, and other large cations. The low partition coefficients for lanthanides, uranium and thorium in phlogopite (<2X 10 ) indicate, however, that large highly charged cations cannot... 

Figure 21 Plot of for phlogopite-melt partitioning versus reciprocal temperature (see text) (A La Tourrette et al. (1995) Green et al. (2000) O Schmidt et al. (1999) Icenhower and London (1995) and Guo and Green (1990)).

Guo J. and Green T. H. (1990) Experimental study of barium partitioning between phlogopite and silicate liquid at upper-mantle pressure and temperature. Lithos 24, 83-96. 

La Tourrette T., Hervig R. L., and Holloway J. R. (1995) Trace element partitioning between amphibole phlogopite and basanite melt. Earth Planet. Sci. Lett. 135, 13-30. 

Other elements are also uniquely partitioned into specific mantle mineral phases. Eor example, potassium, rubidium, and barium partition preferentially into phlogopite (Schmidt et al, 1999). Relative depletions in the abundances of these elements on primitive mantle normalized trace-element plots (see later sections) can therefore serve as evidence of residual phlogopite in the source region of basaltic rocks. Amphibole can also sequester potassium and barium, as well as... 

Mesto, E., Schingaro, E., Scordari, F, Ottolini, L. (2006) Electron probe microanalysis, secondary ion mass spectrometry and single crystal X-ray diffraction study of phlogopites from Mt. vulture, Potenza, Italy consideration of cation partitioning. Am. Mineral, 91,182-190. 

Cruciani, G., Zanazzi, P.F. (1994) Cation partitioning and substitution mechanism in IM phlogopite a crystal chemical study. Am. Mineral, 79,289-301. 

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