| 大别山高级变质岩云母Rb—Sr等时线年龄测定及其地质意义 |
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| 关键词:mica Rb-Sr high-grade metamorphic rock transformation events |
| 基金项目:国家自然科学基金(编号:49902005)，原地质矿产部重大基础项目(95011022-2) |
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| Rb-Sr Mica Dating of High-grade Metamorphic Rocks from the Dabie Mountains and Its Geological Significance |
| A preliminary study on late transformation events of high-grade metamorphic rocks was conducted by means of Rb-Sr da- ting of mica fractions. With heavy liquid separation technology of changing temperatures, the mica concentrate was divided into several fractions with respect to their gravity differences. The fractions were measured by conventional Rb-Sr method. Two samples from the Dabie Mountains were dated by this technique. Biotite samples from the Archean Huangtuling hyperthenegarnetbiotite gneiss were dated at 127±8Ma, which reveals an Yanshanian anatectic-magmatic event superimposed upon the granulite facies rock. The ages are in good agreement with the K-Ar and Ar-Ar ages of amphiboles from the gneisses as well as with the Rb-Sr ages of Yanshanian granites in the area. 8 muscovite fractions from the Shima eclogitefacies garnetbearing gneiss in the southeastern Dabie Mountains define an isochron age of 191±10 Ma. It reflects a low-grade (green schist facies) metamorphic event in the area. The present study demonstrates that there have existed different late-stage geological evolutions of high-grade metamorphic rocks in different tectonic units of the eastern Dabie Mountains since Mesozoic. |
| JIAN Ping.2001.Rb-Sr Mica Dating of High-grade Metamorphic Rocks from the Dabie Mountains and Its Geological Significance[J].Acta Geoscientica Sinica,22(5):409-412. |
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