新疆哈密市路白山一带片麻状花岗岩锆石SHRIMP U-Pb定年及其地质意义
Zircon SHRIMP U-Pb dating of gneissic granite bodies in the Lubai Mountain of Hami, Xinjiang, and its geological significance
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摘要: 提要：新疆哈密市路白山一带出露有片麻状花岗岩，通过对其SHRIMP锆石U-Pb定年、主量和微量元素的研究。锆石207Pb/206Pb比值平均加权年龄为（1453±15）Ma，表明岩石形成于中元古代晚期。岩体的主、微量元素研究表明，岩石化学成分具有富MgO、FeOt、CaO，贫碱、低K2O/Na2O比值；稀土配分曲线表现为明显右倾的轻稀土富集型，大离子亲石元素相对洋脊花岗岩明显富集，Nb、Ta相对亏损，具有岛弧I型花岗岩的特征。该花岗岩的时代确定，对于可能存在的南天山元古宙洋关闭的地质事件首次从岩浆作用上提供了重要信息。
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关键词:
- 锆石 /
- SHRIMP U-Pb定年 /
- 片麻状花岗岩 /
- 路白山
Abstract: Abstract：Some gneissic granite bodies are exposed in the Lubai Mountain of Hami area, Xinjiang. Zircons from these rocks were dated at （1453±15） Ma by SHRIMP, suggesting that their intrusion occurred in middle Proterozoic. Data of major elements and trace elements show that the gneissic granite bodies are enriched in MgO, FeOt, CaO, depleted in alkaline-earth metals and have low K2O/Na2O ratios. REE partition patterns are inclined to the right. The lithophile elements are obviously concentrated whereas Nb and Ta are depleted relative to MOR granite, suggesting characteristics of I type granite. These data provide important information for the possible geological event of the closure of South Tianshan Ocean in Proterozoic.-
Keywords:
- zircon SHRIMP U-Pb dating /
- gneissic granite /
- Lubai Mountain /
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