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-  2017 

Basic principle of clumped isotopes and geological applications

DOI: 10.7605/gdlxb.2017.04.056

Keywords: 团簇同位素,同位素体,碳酸盐,古温度计,甲烷,

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Clumped isotopes are isotopologues containing two or more than two rare isotopes clumping together. The clumped isotope value is used to denote the deviation extent from the stochastic distribution for a certain isotopologue. It is necessary to use a high resolution mass spectrometry to measure an isotopologue with relatively low abundance. The key is to obtain samples' clumped isotope values in the absolute reference frame by choosing a worked gas with known isotopic composition,and heated gases with different isotopic compositions. The relative abundances of clumped isotopes are extremely low,but clumped isotopes have peculiar physical and chemical property. For example,carbonate clumped isotopes(13C18O16O)are sensitive to their growth temperature,in dependent of carbonate bulk isotopic compositions and the oxygen isotope of the growth fluid. As a result,the growth temperature can be easily obtained using the measured clumped isotope value,and the oxygen isotope of the growth fluid can also be obtained combined the bulk carbonate oxygen isotope data using the conventional oxygen paleothemometry model. The clumped isotope paleothermometry has been widely used in the paleoclimate reconstruction,the paleoelevation estimation,carbonate diagenesis,and distinguishing methane origin. The future research focuses include: Evaluation the effect of carbonate C-O reordering resulting from large burial depth and relatively high temperature,the nonlinearity between actual and measured value produced by the mass spectrometry,the method of measuring clumped isotopes with even more lower relatively abundance or clumped isotopes of larger molecules.


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