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    Kinetically controlled variations of major components and carbon and oxygen isotopes in a calcite-precipitating spring
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    Stable isotope analyses of CaCO 3 minerals are very important for investigations of paleoclimate and sedimentary environments For this reason, the experimental calibration of oxygen isotope fractionation factors in the system of CaCO 3 H 2O has been an attractive subject in stable isotope geochemistry since its birth However, there are considerably large differences in the oxygen isotope fractionation factors between CaCO 3 and H 2O measured by different investigators, due to CaCO 3 polymorphs in nature ( i e calcite, aragonite and vaterite) As a result, different temperatures are yielded when these different fractionation factors are applied to isotope geothermometry Thus it is of critical importance in low temperature and environmental geochemistry to make the correct and reasonable choice of oxygen isotope fractionation equations in the calcite water and aragonite water systems In this paper the experimental calibration history, approaches and results of oxygen isotope fractionations in the CaCO 3 H 2O system are systematically summarized and reviewed, and the different expressions about the oxygen isotope fractionation between CaCO 3 and H 2O are unified Salt effect and kinetic effect on oxygen isotope fractionation as well as oxygen isotope inheritance in the processes of polymorph transformation are discussed as well The equilibrium equation of oxygen isotope fractionation between calcite and water is recommended on the basis of reprocessing a large number of the known experimental data and comparing them with theoretical calculations However, the theoretical calculation results concerning the aragonite water system has to be confirmed by further experiments
    Equilibrium fractionation
    Mass-independent fractionation
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