| Fe同位素在岩浆作用过程中的分馏效应及其对海底玄武岩形成过程的指示 |
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| 引用本文： | 郭泽华,翟世奎,于增慧.Fe同位素在岩浆作用过程中的分馏效应及其对海底玄武岩形成过程的指示[J].海洋学报,2022,44(9):1-12. |
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| 作者姓名： | 郭泽华 翟世奎 于增慧 |
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| 作者单位： | 1.中国海洋大学 海洋地球科学学院, 山东 青岛 266100 |
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| 基金项目： | 国家重点基础研究发展计划（2013CB429702）。 |
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| 摘 要： | Fe是火成岩中丰度最高的变价元素，也是重要的成矿元素，主要以Fe2+或Fe3+价态赋存于固（矿物）、液（流体）相中，并全程参与岩浆作用过程和各种成矿作用。随着测试分析技术（如MC-ICPMS）的发展，Fe等非传统稳定同位素组成分析成为可能，并在最近十几年中被成功应用于岩浆物源追溯、结晶演化过程示踪和成矿作用分析等重要地质作用过程的研究。本文在分析了Fe同位素在岩浆作用过程中分馏效应的基础上，总结了Fe同位素组成在示踪海底玄武质岩浆（MORB、OIB、IAB和BABB等）作用过程研究的最新成果，并探讨了在应用Fe同位素组成示踪海底岩浆作用过程中所存在的主要问题。综合分析结果表明，火成岩中的Fe同位素分馏效应不仅受岩浆源物质部分熔融、岩浆扩散、流体出溶和结晶分异等作用过程的影响，而且还受到同化围岩物质、海底蚀变等作用的影响；由于Fe同位素分析技术（方法）至今仍待进一步完善，已有数据有限且需甄别去伪，因此在利用Fe同位素组成分析或恢复岩浆物源及作用过程时，仍需谨慎；于当前亟需建立完整可靠的Fe同位素示踪体系，这就需要在近期的工作中，尽可能多地选取代表不同构造环境和不同岩石类型的合适样品、获取（积累）更多原始（未经改造或蚀变）样品的精细分析数据，同时在利用Fe同位素示踪海底岩浆作用过程中还需注重多元数据的结合或相互佐证。
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| 关 键 词： | 铁同位素 分馏效应 同位素示踪 海底岩浆作用 |
| 收稿时间： | 2021-10-27 |
Fractionation effect of iron isotope during magmatism and its indication of submarine basalt formation process |
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| Institution: | 1.College of Marine Geosciences, Ocean University of China, Qingdao 266100, China2.Key Lab of Submarine Geosciences and Pro- specting Techniques, Ministry of Education, Qingdao 266100, China |
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| Abstract: | Fe is the most abundant variable-valence element in igneous rocks, and is also an important mineralizing element, mainly in the solid (mineral) and liquid (fluid) phases in Fe2+ or Fe3+ valence state, and participates in magmatic processes and various mineralization throughout. With the development of test analytical techniques (e.g. MC-ICPMS), the analysis of non-traditional stable isotope compositions such as Fe has become possible and has been successfully applied to the study of important geological processes such as magma source tracing, tracing of crystallization evolutionary processes and mineralization analysis in the last decade or so. Based on the analysis of the fractionation effect of Fe isotopes during magmatism, this paper summarized the latest results of Fe isotope composition studies in tracing the action of seafloor basaltic magmas (MORB, OIB, IAB and BABB, etc.) and discussed the main problems in the application of Fe isotope composition in tracing the action of seafloor magmas. The results of the comprehensive analysis show that the Fe isotope fractionation effect in igneous rocks is influenced not only by the processes of partial melting of magma source material, magma diffusion, fluid exsolution and crystallization differentiation, but also by the assimilation of surrounding rock material and seafloor alteration. Since Fe isotope analysis techniques (methods) have yet to be further refined, and the available data are limited and need to be screened for artifacts, caution is still needed when using Fe isotope compositions to analyze or recover magmatic sources and processes. It is urgent to establish a complete and reliable Fe isotope tracing system, which requires the recent work to select as many suitable samples as possible representing different tectonic environments and different rock types, to obtain (accumulate) more fine analytical data of original (unmodified or altered) samples, and to pay attention to the combination or mutual corroboration of multiple data in the process of using Fe isotope tracing for seafloor magmatism. |
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