| 壳幔Rb—Sr混合等时线及其地质意义 |
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| 引用本文： | 李龙,郑永飞.壳幔Rb—Sr混合等时线及其地质意义[J].地质论评,2000,46(2):120-130. |
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| 作者姓名： | 李龙 郑永飞 |
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| 作者单位： | 中国科学技术大学地球和空间科学系,合肥,230026 |
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| 基金项目： | 中国科学院项目 (编号KZ952-J1-409)，国家自然科学基金 (编号49453003) |
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| 摘 要： | 本文利用二元混合模型讨论了壳幔物质的不同混合环境对Ｒｂ－Ｓｒ等时线年龄的影响。一般情况下，混合作用将使岩体的同位素年龄变大；若地壳物质在混合之前经受过Ｒｂ丢失和（或）Ｓｒ获得事件，则等时线斜率的变化较大，可能得到很大的年龄和异常低的初始同位素比值，甚至斜率为负值。对一组分离的底辟小岩体而言，同一底辟岩体作矿物内部等时线能够得到结晶年龄，但用不同岩体的全岩得到的等时线则可能给出围岩年龄（条件是各底辟
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| 关 键 词： | 壳幔混合 地质事件 铷－锶等时线 地质意义 |
Effect of Crust-Mantle Mixing Environments on Rb-Sr Isochron Age and Its Geological Significance |
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| Li Long Zheng Yongfei.Effect of Crust-Mantle Mixing Environments on Rb-Sr Isochron Age and Its Geological Significance[J].Geological Review,2000,46(2):120-130. |
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| Authors: | Li Long Zheng Yongfei |
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| Institution: | Li Long Zheng YongfeiDepartment of Earth and Space Sciences,University of Science and Technology of Chin,Heifei |
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| Abstract: | The effect of different crust-mantle mixing environments on Rb-Sr isochron ages is discussed in terms of a two-component mixing model. Normally, the mixing of mantle magma with crust material will result in an older isotopic age than the crystallization age of a magmatic massif. If the crust material experienced a Rb-lost or/and Sr-gained event, the slope of the isochron will vary greatly depending on the isotopic ratios of the two components. The slope may result in a very old age and abnormally low initial isotopic ratio, sometimes even a negative slope. If the mixing was done through separate diapirism, the crystallization age for the series of small diapirs can be derived by the internal mineral isochron of a single small diapir, and the age of the country rock may also be derived by the whole-rock isochron of different diapirs (assuming the same mixing proportions for every diapir). The present study can shed light on some confusion in interpreting Rb-Sr isochron ages. |
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| Keywords: | crust-mantle mixing geological events Rb-Sr isochron age significance |
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