Detrital Quartz and K-Feldspar in Quartzites as Indicators of Oxygen Isotope Exchange Kinetics

  • S. Hoernes
  • G. Voll

Abstract

Oxygen isotope fractionation between coexisting minerals may indicate equilibrium or disequilibrium, provided the temperature of formation is known. Depending on the time of blocking of specific 18O/16O ratios, the fractionations contain information on:
  1. 1.

    Pre-peak-metamorphic conditions as assumed by Wenner and Taylor (1973) for serpentine-magnetite fractionations or by Hoernes and Hoffer (1979) for metamorphic parageneses in a more general sense. In this case oxygen isotope temperatures represent formation temperatures.

     
  2. 2.

    Peak-metamorphic conditions; equilibrium is thought to be reached by exchange reactions via a fluid phase, by recrystallization (Hoernes and Friedrichsen 1978), or by mineral reactions.

     
  3. 3.

    Post-peak-metamorphic conditions; based on different rates of oxygen diffusion in different minerals, it is thought that 18O/16O ratios are fixed at different temperatures during cooling, as demonstrated by Deines (1977) for specific minerals and recently discussed by Giletti (1986). The postmagmatic exchange reactions discussed in Hoernes et al. (Chap. 17, this Vol.) belong in this category. For further discussion see Hoefs (1987), O’Neil (1986), Valley (1986).

     

Keywords

Crystallization Quartz Recrystallization Fractionation Beach 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1991

Authors and Affiliations

  • S. Hoernes
  • G. Voll

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