Equilibrium high-temperature Fe isotope fractionation between fayalite and magnetite: An experimental calibration
نویسندگان
چکیده
The iron isotopic fractionation factor between magnetite and fayalite was measured at high temperature in a piston–cylinder apparatus. For the first time, the three-isotope method [Matsuhisa, J., Goldsmith, J. R., and Clayton, R. N., 1978. Mechanisms of hydrothermal crystallisation of quartz at 250 °C and 15 kbar. Geochim. Cosmochim. Acta 42, 173–182.] has been used to determine equilibrium fractionation between two minerals directly. The experimentally-determined temperature-dependent iron isotope fractionation between fayalite and magnetite is described by 10ln αMag–Fa≅ΔFeMag–Fa=0.30 (+/−0.024)×10 / T. The equation predicts measurable fractionation at magmatic temperatures. Our work bears on the magnitude of Fe isotope fractionation attending differentiation in magmatic systems and provides a new isotope thermometer for coexisting fayalite and magnetite. © 2008 Elsevier B.V. All rights reserved.
منابع مشابه
Experimental calibration of oxygen isotope fractionation between quartz and zircon
We report the results of an experimental calibration of oxygen isotope fractionation between quartz and zircon. Data were collected from 700 to 1000 C, 10–20 kbar, and in some experiments the oxygen fugacity was buffered at the fayalite–magnetite–quartz equilibrium. Oxygen isotope fractionation shows no clear dependence on oxygen fugacity or pressure. Unexpectedly, some high-temperature data (9...
متن کاملThermodynamic constraints on fayalite formation on parent bodies of chondrites
available online at http://meteoritics.org Thermodynamic constraints on fayalite formation on parent bodies of chondrites Mikhail Yu. ZOLOTOV1*, Mikhail V. MIRONENKO2, and Everett L. SHOCK1, 3 1School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287–1404, USA 2Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygin Street ...
متن کاملOxygen Isotopic Compositions of Fayalite in the Kaba Cv3 Carbonaceous Chondrite
INTRODUCTION The Fe-rich olivine end-member, fayalite (Fa100), occurs in the matrix, chondrules, CAIs, silicate aggregates, and dark inclusions in the oxidized Kaba and Mokoia CV3 chondrites, where it is associated with magnetite and troilite. To help constrain the origin of the fayalite, we measured O-isotope compositions of fayalite (Fa98-100) from two petrographic settings of the Kaba meteor...
متن کاملA general moment NRIXS approach to the determination of equilibrium Fe isotopic fractionation factors: Application to goethite and jarosite
The equilibrium Fe isotopic fractionation factors of goethite and jarosite have considerable importance for interpreting Fe isotope variations in low temperature aqueous systems on Earth and possibly Mars in the context of future sample return missions. We measured the b-factors of goethite FeO(OH), potassium-jarosite KFe3(SO4)2(OH)6, and hydronium-jarosite (H3O)Fe3(SO4)2(OH)6, by Nuclear Reson...
متن کاملOxygen Isotope Ratios in the Crust of Iron Meteorites
The separation factor, aM-0= ( 1 8 0 / 1 6 0 ) magnetite/' ( 1 8 0 / 1 6 0 ) atmospheric oxygen, between the magnetite crust of iron meteorites and atmospheric oxygen has been determined to be 0.9946 ± 0.0005. It is concluded that this fractionation of the oxygen isotopes is the consequence of an equilibrium isotope effect at high temperatures. It can be assumed that this is also valid for cosm...
متن کامل