| 非传统稳定同位素示踪深部物质的理论模型与应用 |
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| 引用本文：孙剑.2025.非传统稳定同位素示踪深部物质的理论模型与应用[J].地球学报,46(2):429-437. |
| DOI：10.3975/cagsb.2024.111921 |
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| 基金项目:国家重点研发计划(编号: 2019YFA0708604)；国家自然科学基金项目(编号: 42072113; 42273051)；中国地质调查局地质调查项目(编号: DD20243516)；中国地质科学院基本科研业务费(编号: JKYQN202322) |
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| 中文摘要:近20年来, 非传统稳定同位素体系迅速发展, 在示踪地球深部物质组成、循环与演化方面显示出巨大的应用前景。尽管如此, 如何应用同位素数据提取与解译深部信息, 尚缺乏统一的数学理论模型。本文首先总结介绍非传统稳定同位素的基本性质与示踪潜力。在此基础上, 初步提出一个公式化的示踪理论模型。该模型考虑源区物质同位素组成和高温过程的同位素分馏, 变量包括: 初始地幔的同位素组成、再循环物质加入、地幔交代过程、源区矿物组成、部分熔融的氧逸度条件、部分熔融的温度压力条件、岩浆演化过程、岩浆期后过程等。通过计算各变量造成的同位素分馏大小、确定主要控制变量, 有望定量化提取深部物质组成和岩浆过程信息, 为定量化模拟计算奠定基础; 最后以Mg、Zn和Ca同位素示踪地幔中再循环地表碳酸盐为例, 介绍了该模型的应用方法。 |
| 中文关键词:非传统稳定同位素 深部物质示踪 再循环碳酸盐 玄武岩 火成碳酸岩 |
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| Theoretical Models and Applications of Non-traditional Stable Isotopes in Tracing the Deep Earth |
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| Abstract:Non-traditional stable isotope geochemistry has developed rapidly over the past two decades, emerging as powerful tools for tracing the composition, cycling, and evolution of deep Earth materials. However, the numerous factors that cause isotopic fractionation present challenges in quantitatively or semi-quantitatively extracting deep Earth information from isotopic data. In this paper, we first summarize the basic properties and potential applications of non-traditional stable isotopes in deep Earth area. We then propose a theoretical model with a mathematical formula incorporating variables of the isotopic composition of source materials and isotopic fractionation during high-temperature processes. Sepcifically, the variables include the isotopic composition of the initial mantle, the addition of recycled materials, the mantle metasomatism, the mineral composition of the source area, conditions of partial melting (such as oxygen fugacity, temperature and pressure conditions), magma evolution processes, and post-magma processes. By determing the primaly controlling factors and calculating isotopic fractionation values associated with different variables, this model allows for the quantitative extraction of information on deep Earth materials composition and igneous processes. An example of tracing recycled carbonates by Mg, Zn, and Ca isotopes is presented to show how this model can be applied to study the deep Earth. |
| keywords:non-traditional stable isotopes deep material trace recycled carbonate basalt carbonatite |
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