Original paper

Oxygen isotope fractionation between zircon and water: experimental determination and comparison with quartz-zircon calibrations

Krylov, Dmitry P.; Zagnitko, Vasilij N.; Hoernes, Stephan; Lugovaja, Irina P.; Hoffbauer, Radegund


Oxygen isotope fractionation between synthesised zircon and water has been experimentally quantified at 700, 800, 900, and 1000 °C.The results are interpolated by: Δzrn-H20 = -3.70 + 2.74 ± 0.19 x², where x = 10³/T (K). Combined with the fractionation between quartz and water (Bottinga & Javoy, 1973) this yields: Δqtz-zrn = 1.36 x². Theoretical evaluations of the reduced partition function ratios for zircon and two (α- and β-) modifications of quartz are expressed in terms of the following polynomials: 1000 lnfzrn= 8.3306 x² + 1.9402 x - 0.6896 (400 < t < 1100°c) 1000 lnfα-qtz= 7.8963 x² + 7.4091 x - 3.6015 (200°C < t < α-quartz stability field) 1000 lnfβ-qtz= 9.3362 x² + 2.4514 x - 0.7844 (β-quartz stability field up to 1100 °C). These expressions are in excellent agreement both with the experimentally derived factors of oxygen isotope fractionation for β-quartz and zircon, and the incremental calibrations for α-quartz and zircon (Hoffbauer et al. , 1994). The effect of α-β-quartz transition on oxygen isotope fractionation implies, that those calculations, anchored to the theoretically evaluated reduced partition function ratios of quartz (e.g. , Zheng, 1993), can predict fractionations only within the P-T stability field of the respective modification of quartz (i.e. α-quartz).


oxygen isotopeszircon water fractionationquartzgeothermometry