| 大别山双河地区花岗质片麻岩锆石的离子探针定年 |
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| 引用本文： | 吴元保,陈道公,夏群科,程昊.大别山双河地区花岗质片麻岩锆石的离子探针定年[J].矿物岩石地球化学通报,2001,20(4):298-301. |
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| 作者姓名： | 吴元保 陈道公 夏群科 程昊 |
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| 作者单位： | 中国科学技术大学地球与空间科学系,安徽,合肥,230026 |
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| 基金项目： | 科技部基础研究发展规划项目 ( 1999G0 75 5 43)，国家自然科学基金联合资助项目 |
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| 摘 要： | 对双河花岗质片麻岩的锆石进行了阴极发光分析 ,结果表明存在两种类型的锆石 (残留锆石和原岩中的岩浆锆石 )。对其进行离子探针定年显示原岩的岩浆锆石形成于 10 2 5Ma ,在超高压和后期的退变质事件中都存在铅丢失现象 ,其 197Ma变质作用的年龄不能反映超高压事件峰期变质作用的年龄。残留锆石的形成年龄为 2 86 1Ma的晚太古代年龄 ,这些锆石在超高压变质作用中发生了较严重的重结晶作用 ,对应于 2 30Ma左右的峰期变质作用的年龄 ,后期退变质作用对其影响较小。
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| 关 键 词： | 大别山 双河 花岗片麻岩 锆石 离子探针定年 |
| 文章编号： | 1007-2802(2001)04-0298-04 |
| 修稿时间： | 2001年7月5日 |
SIMS U-Pb Dating of Zircons from Shuanghe Orthogneiss, Dabie Area |
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| WU Yuan-bao,CHEN Dao-gong,XIA Qun-ke,CHENG Hao.SIMS U-Pb Dating of Zircons from Shuanghe Orthogneiss, Dabie Area[J].Bulletin of Mineralogy Petrology and Geochemistry,2001,20(4):298-301. |
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| Authors: | WU Yuan-bao CHEN Dao-gong XIA Qun-ke CHENG Hao |
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| Abstract: | The CL images of zircons from Shuanghe orthogneiss reveal that there are two kinds of zircons (inherited and magmatic zircons from the protolith). Nine points of six zircons were dated with SIMS on the bases of CL images. They are all discordant, indicating Pb loss after their formation. Four analyses of magmatic zircons define a chord intersecting the concordant curve at 1 025 Ma and 197 Ma respectively. According to the CL images, the upper intercepted age represented the magmatic protolith age, the lower intercept defined the metamorphic event. This metamorphic age may not represent the UHP metamorphism, but the retrograde metamorphic age. The age of inherited zircons is 2 861 Ma. These old inherited zircons experienced recrystallization during UHP metamorphism. The ca. 230 Ma metamorphic age maybe nearly represent the peak UHP metamorphic age. |
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| Keywords: | Dabieshan Shuanghe orthogneiss zircon SIMS dating |
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