Rutile partitioning

Foley SF, Barth MG, Jenner GA (2000) Rutile/melt partition coefficients for trace elements and an assessment of the influence of ratile on the trace element characteristics of subduction zone magma. Geochim Cosmochim Acta 64 933-938... 

Brenan JM, Shaw HF, Phinney DL, Ryerson FJ, (1994) Rutile-aqueous fluid partitioning of Nb, Ta, Hf, Zr, U and Th implications for high field strength element depletions in island-arc basalts. Earth Planet Sci Lett 128 327-339... 

D s were calculated assuming 60% cpx, 40% garnet and no rutile using values from Keppler (1996) and gamet/melt cpx/melt partition coefficients to estimate gamet/fluid partitioning. ... 

Figure 11.30 Reduced partition function for various minerals calulated by Kieffer (1982) through equation 11.61 plotted against T. Heavy curve labeled H20(l) is reduced partition function of water according to Becker (1971). Dashed curve is a extrapolation of high-r reduced partition curve for quartz. Mineral abbreviations Qtz (quartz), Calc (calcite), Albt (albite), Muse (muscovite), Enst (clinoenstatite), Anor (anorthite). Diop (diopside), Pyrp (pyrope), Gros (grossular), Zron (zircon), Fors (forsterite), Andr (andra-dite), Rutl (rutile). Reprinted with permission from Kieffer (1982), Review of Geophysics and Space Physics, 20, 827-849, copyright 1982 by the American Geophysical Union.

The Kieffer model correctly predicts the systematic change of the reduced partition functions of various minerals with structure, as indicated by Taylor and Epstein (1962). For anhydrous sihcates, the decrease in the sequence framework-chain-orthosilicate reflects the decreasing frequency of antisymmetric Si-O stretching modes. The internal frequencies of the carbonate ion give a high reduced partition function at all T. The value for rutile is low because of the low frequencies of the Ti-0 modes (Kieffer, 1982). 

Fig. 2.1. A representation of the Madelung field of rutile (Ti02, 202240) in the (110) plane (x,y,z) x + y — 1. The light lines represent the field lines, the heavy lines show the zero-flux boundary that partitions space into bonds (from Preiser et al. 1999).

Figures 11 and 12 give the partitioning of the electron density between Pt and H in the PtFLt2- stack, and between Ti and O in rutile. Everything is as 27 and 29 predict, as the chemist knows it should be the lower orbitals are localized in the more electronegative ligands (H or O), the higher ones on the metal.

Thorium and uranium contents of apatite vary widely but are normally very high compared to other mantle phases (generally >10 ppm Table 9 Ionov et al, 1997). Apatites in MARID xenoliths tend to have lower uranium (Kramers et al, 1983), possibly due to uranium partitioning into rutile or zircon. Lead contents are the highest reported for the common mantle minerals but U/Pb is generally PUM. 

Stalder R., Foley S. F., Brey G. P., and Horn I. (1998) Mineral-aqueous fluid partitioning of trace elements at 900-1200°C and 3.0-5.7 GPa new experimental data for garnet, clinopyroxene and rutile and implications for mantle metasomatism. Geochim. Cosmochim. Acta 62, 1781-1801. 

Elcombe and Hulston 1975 Kawabe 1978). Kieffer (1982) took a less detailed approach in calculating oxygen isotope partition function ratios for 11 silicate minerals, calcite and rutile. As input for her calculations, Kieffer used the measured spectra for the forms of minerals, divided the vibrational modes for these minerals into four groups, and then developed a set of rules for estimating the frequency shift associated with each group on substitution. Importantly, she applied the same rules to each mineral considered in her study, which resulted in an internally consistent set of partition function ratios. Most of Kieffer s calculated fractionation factors are in excellent agreement with experimental data (Clayton and Kieffer 1991). 

The use of crosslinked polymers of high specific surface area as stationary phase in the separation of some mixtures has extended the application of gas chromatography to the study of specific surface area of polymers [il4—116]. Thus, polymeric porous powders were studied, such as polyethylene [117], crosslinked copolymers of styrene, divinylbenzene, and ethyl vinyl benzene which may also contain other polar co-monomers whose commercial names are Porapak and Chromosorb [118, 119], carbon black, zeolites treated with poly(ethylene oxide) [120], and silicagel and rutile treated similarly [121, 122]. Although the mechanism of partition on these porous polymers is disputed it seems that adsorption has an important share [116]. 

Green and Pearson [44] give rutile partition coefficients for Nb and Ta. Experimental conditions were 10(X) C and 4-16 kbar near MW. Liquid compositions were hydrous andesite and frachyte. Dfjb = 26-30 and Dja = 44-45. The sense of partitioning is similar to that observed by [146] in synthetic systems. 

Wendlandt, R. F., Partitioning of niobium and tantulum [sic] between rutile and silicate melt (abstract), Eos Trans. AGU, 71, 1658. 1990. 

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