Empirical calibration of oxygen isotope fractionation in zircon

Inter-mineral Fe isotope variations in mantle-derived rocks and implications for the Fe geochemical cycle

“…The one sample (CS-ND-3B) that has a low ⌬ 56 Fe cpx-gt fractionation of ϩ0.07‰, and does not follow the same trend as the others, has a very low garnet Ca content (Fig. 6C), and it remains to be seen if Ca content in garnet plays the same crystal chemical control on Fe isotope fractionation as it does for O isotope fractionation (Kohn and Valley, 1998;Valley et al, 2003). Significant Fe isotope fractionation between garnet and clinopyroxene raises the possibility that Fe isotope variations may be produced within the mantle during crystal fractionation of basalts at mantle pressures, where garnet may be a liquidus phase.…”

The role of volatile exsolution and sub-solidus fluid/rock interactions in producing high 56Fe/54Fe ratios in siliceous igneous rocks

“…Isotopic data are reported as 56 Fe/ 54 Fe and 57 Fe/ 54 Fe ratios in standard delta (d) notation, in units of per mil (&), and using the average of igneous rocks as the standard reference reservoir (Beard et al, 2003a): Hagstrum and Johnson (1986) and the calibration of Clayton and Kieffer (1991); TIS temperatures provided by J.S. Lackey calculated from Quartz-Zircon and Zircon-Titanite d 18 O thermometry (Lackey, 2005) with calibrations of Valley et al (2003). Fe-Ti temperatures for volcanic rocks as follows: Seguam Island, provided by B.R.…”

“…Temperatures for TIS were provided by J.S. Lackey and calculated based on quartz-zircon and zircon-titanite oxygen isotope thermometry with calibrations of Valley et al (2003). d 56 Fe values observed in Fig.…”

Oxygen isotopic composition and U-Pb discordance in zircon

“…Following the development of techniques for laser fluorination of very small samples, as well as in situ analysis by ion microprobe, ␦ 18 O has now been measured in many zircons, primarily by Valley et al (1994Valley et al ( , 1998Valley et al ( , 2003; Eiler et al (1997); Peck et al (2001Peck et al ( , 2003; and Valley (2003). Among numerous observations, Valley (2003) noted that for zircons from the Adirondack Highlands, ␦ 18 O is heavier in zircons with lower magnetic susceptibility, lower U content, and more concordant ages.…”

“…Keeping in mind the implications that texture has for growth mechanisms, in addition to the fractionation between zircon and coexisting minerals (i.e., Valley et al, 2003), we propose the following history for IG2D-01.…”