古地理学报 ›› 2017, Vol. 19 ›› Issue (4): 713-728. doi: 10.7605/gdlxb.2017.04.056

• 地球化学与沉积环境 • 上一篇    下一篇

团簇同位素的基本原理与地质应用*

李平平1, 马倩倩1, 邹华耀1, 余新亚2   

  1. 1 中国石油大学(北京)油气资源与探测国家重点实验室,北京 102249;
    2 中国地质大学(武汉)构造与油气资源教育部重点实验室,湖北武汉 430074
  • 收稿日期:2017-05-22 修回日期:2017-05-30 出版日期:2017-08-01 发布日期:2017-08-07
  • 作者简介:李平平,男,1980年生,副教授,主要从事碳酸盐岩储集层地质学和油气成藏机理研究。E-mail: lpp@cup.edu.cn。
  • 基金资助:

    *国家自然科学基金项目(编号: 41672122,U1663210)和国家留学基金共同资助

Basic principle of clumped isotopes and geological applications

Li Pingping1, Ma Qianqian1, Zou Huayao1, Yu Xinya2   

  1. 1 State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249;
    2 Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education,China University of Geosciences(Wuhan),Wuhan 430074,Hubei;
  • Received:2017-05-22 Revised:2017-05-30 Online:2017-08-01 Published:2017-08-07
  • About author:Li Pingping,born in 1980,is an associate professor. He is mainly engaged in researches of carbonate reservoir and hydrocarbon accumulation mechanism. E-mail: lpp@cup.edu.cn.
  • Supported by:

    Co-funded by the National Natural Science Foundation of China(Nos.41672122,U1663210)and China Scholarship Council

摘要:

团簇同位素指的是含有2个及2个以上的重同位素结合在一起形成的同位素体。团簇同位素的数值定义为同位素体的相对丰度偏离随机分布状态的程度。测量该相对丰度较低的同位素体需要高精度的质谱仪,难点在于利用同位素组成已知的参考气体和不同同位素组成的加热气体,以获得绝对参考体系下的数值。团簇同位素体的相对丰度非常低,但是具有非常独特的物理和化学性质。比如碳酸盐矿物中13C18O16O的丰度对温度具有敏感性,而与矿物的全岩同位素以及矿物形成时期的流体性质无关,因此可以利用测量的碳酸盐团簇同位素来获得矿物的生长温度,再利用矿物的氧同位素(δ18O),根据传统的氧同位素温度计原理,可以进一步获得矿物的生长流体(水)的氧同位素。目前,团簇同位素温度计已经在古气候(温度)重建、古高度恢复、碳酸盐岩的成岩作用以及甲烷的成因分析等方面得到了广泛应用。评估深埋高温过程引起的C-O化学键重置对碳酸盐团簇同位素的影响、测试仪器产生对团簇同位素的非线性误差校正、以及其他丰度更低的团簇同位素体或大分子的团簇同位素的测量,是下一步的研究方向。

关键词: 团簇同位素, 同位素体, 碳酸盐, 古温度计, 甲烷

Abstract:

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.

Key words: clumped isotope, isotopologue, carbonate, paleothermometry, methane

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