| 山东青岛灵山岛流纹岩岩石成因及构造环境新认识 |
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| 引用本文： | 张书凯,孟元库,王泽利.山东青岛灵山岛流纹岩岩石成因及构造环境新认识[J].高校地质学报,2019,25(5):654. |
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| 作者姓名： | 张书凯 孟元库 王泽利 |
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| 作者单位： | 山东科技大学地球科学与工程学院,青岛,266590;山东科技大学地球科学与工程学院,青岛,266590;山东科技大学地球科学与工程学院,青岛,266590 |
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| 基金项目： | 山东省自然科学基金博士基金 |
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| 摘 要： | 文章对灵山岛上的两件流纹岩样品进行了系统的锆石U-Pb测试，获得加权平均年龄分别为123.1±1.9 Ma和121.4±
1.4 Ma，两个年龄在误差范围内一致，代表了灵山岛流纹岩的成岩年龄。地球化学组成上，灵山岛流纹岩具有高硅、高碱
和低磷、低Mg#、低钛和低钙的特征，富集Rb、Th和K等大离子亲石元素以及轻稀土元素，亏损Nb、Ta、Ti和P等高场强
元素。岩石组合和地球化学特征以及低的全岩锆饱和温度综合表明，灵山岛流纹岩属于高分异的I型流纹岩，而非伸展环
境下形成的A型流纹岩，属于苏鲁造山带后碰撞岩浆活动的产物。流纹岩的锆石εHf(t)值变化范围较小（-27.2~-32.3），二阶
段模式年龄tDM2主要为新太古代—中太古代（2662~3167 Ma），表明流纹岩是古老地壳物质重熔的产物。灵山岛流纹岩中新
元古代继承锆石的发现暗示其源于扬子古老陆壳（中地壳） 的部分熔融。综合结果表明：早白垩世时，华北克拉通破坏是
引起扬子壳源物质发生大规模（减压） 部分熔融的内在因素，岩石圈破坏形成的区域性伸展构造为流纹岩的最终上升和就
位提供了空间。
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| 关 键 词： | 灵山岛 岩石成因 锆石U-Pb测年 Hf同位素 后碰撞伸展 |
New Insight into Petrogenesis and Tectonic Setting of the Rhyolite from the Lingshan Island in Qingdao Region,Shandong Province |
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| ZHANG Shukai,MENG Yuanku,WANG Zeli.New Insight into Petrogenesis and Tectonic Setting of the Rhyolite from the Lingshan Island in Qingdao Region,Shandong Province[J].Geological Journal of China Universities,2019,25(5):654. |
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| Authors: | ZHANG Shukai MENG Yuanku WANG Zeli |
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| Abstract: | In this study, we conducted systematically zircon U-Pb dating of two representative rhyolite samples from the Lingshan
Island in Qingdao, Shangdong Province. The results show that the weighted ages of two rhyolite samples are ca. 123.1±1.9 Ma and 121.4±
1.4 Ma. These two ages are consistent within the uncertainty, representing the formation and crystallization age of the rhyolite.
Geochemically, the rhyolite samples show high contents of SiO2 and Na2O+K2O, while they are characterized by low contents of P2O5 TiO2
and CaO, as well as low Mg# values. In addition, the rhyolite samples are enriched in LILEs (Rb, Th and K) and LREEs, but depleted in
HFSEs (e.g. Nb, Ta, Ti and P). Rock assemblages, geochemical features, and low whole-rock Zr saturation temperatures indicate that the
rhyolites belong to highly-fractionated I-type rhyolite rather than A-type rhyolite in an extensional setting, and are products of
post-collisional magmatism. The zircon εHf(t) values range from -27.2 to -32.3, and the sencond stage model ages are between 2662 and
3167 Ma, indicating that the rhyolite was origanited from partial melting of ancient crust. The presence of Neoproterozoic inherited
zircons indicates that it was originated from partial melting of the Yangtze middle-crustal material. These results suggest that the
destruction of North China Craton (NCC) was the cause, leading to large-scale partial melting of the Yangtze crustal material. The
regional extensional tectonics related to the destruction of NCC provided emplacement space for the rhyolite in the last stage. |
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| Keywords: | Lingshan Island petrogenesis Zircon U-Pb dating Hf isotope post-collisional extension |
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