| 大别山双河超高压变质矿物Ｏ同位素平衡及其对Sm-Nd和Rb-Sr等时线年龄有效性的制约 |
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| 引用本文：赵子福,郑永飞,李曙光,龚冰.2005.大别山双河超高压变质矿物Ｏ同位素平衡及其对Sm-Nd和Rb-Sr等时线年龄有效性的制约[J].地球学报,26(z1):98-101. |
| DOI：10.3975/cagsb.2005.s1.33 |
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| 基金项目:本文为国家973项目（编号G1999075503）研究成果。 |
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| 中文摘要:对大别造山带双河超高压榴辉岩和片麻岩Sm-Nd和Rb-Sr等时线矿物进行了O同位素地质测温。尽管Sm-Nd等时线给出一致的三叠纪年龄(213~238 Ma)，同一样品Rb-Sr等时线却给出侏罗纪年龄(171~174 Ma)。片麻岩、榴辉岩和榴闪岩矿物对O同位素测温得到600~720℃和420~550℃两组温度，分别对应于约225±5 Ma榴辉岩相变质和约175±5 Ma角闪岩相退变质条件下停止同位素扩散交换的温度。同一样品三叠纪Sm-Nd等时线年龄的保存、侏罗纪Rb-Sr等时线年龄的出现以及有规律的O同位素温度，表明在角闪岩相退变质过程中，Sr和O在含水矿物（如黑云母和角闪石）中的扩散速率在手标本尺度上比石榴石Nd和多硅白云母Sr的扩散速率快。 |
| 中文关键词:榴辉岩和片麻岩 O同位素 Sr-Nd同位素 矿物等时线 扩散平衡 |
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| Oxygen Isotope Equilibrium between UHP Metamorphic Minerals at Shuanghe in the Dabie Orogenic Belt and Its Constraints on Sm-Nd and Rb-Sr Chronometers |
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| Abstract:As the rates of Nd, Sr and O diffusion in metamorphic minerals are comparable in many cases, the state of O isotope equilibrium between metamorphic minerals can provide a test for the validity of mineral Sm-Nd and Rb-Sr chronometers. In order to illustrate this applicability, the authors carried out O isotope geothermometry for Sm-Nd and Rb-Sr isochron minerals from UHP eclogites and gneisses at Shuanghe in Dabie terrane of eastern Central China. Although the Sm-Nd isochrons give consistent Triassic ages of 213~238 Ma for eclogite-facies metamorphism, the Rb-Sr isochrons give Jurassic ages of 171~174 Ma for the same samples. O isotope geothermometry of the gneiss, eclogite and amphibolite minerals yields two sets of temperatures of 600~720℃and 420~550℃，respectively, corresponding to the cessation of isotopic exchange by diffusion at about 225±5 Ma during eclogite-facies recrystallization and that at about 175±5 Ma during amphibolite-facies retrogression. |
| keywords:eclogue and gneiss oxygen isotopes Sr-Nd isotopes mineral isochron diffusion equilibrium |
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