内蒙古德言其庙斜长角闪岩系年代学、地球化学特征及其地质意义-《地球科学与环境学报》

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Title:: Geochronological, Geochemical Characteristics and Geological Significance of Deyanqimiao Amphibolite Series in Inner Mongolia

作者:: 王新; 徐仲元; 刘正宏; 辛后田; 白新会; 王挽琼; 时溢; 1. 吉林大学地球科学学院,吉林长春 130061； 2. 天津地质矿产研究所,天津 300170； 3.西南石油大学地球科学与技术学院,四川成都 610500； 4. 中国地质调查局沈阳地质调查中心，辽宁沈阳 110034

Author(s):: WANG Xin; XUZhong-yuan; LIU Zheng-hong; XIN Hou-tian; BAI Xin-hui; WANG Wan-qiong; SHI Yi; 1. School of Earth Sciences, Jilin University, Changchun 130061, Jilin, China； 2. Tianjin Institute of Geology and Mineral Resources, Tianjin 300170, China； 3. School of Geoscience and Technology,Southwest Petroleum University, Chengdu 610500, Sichuan, China; 4. Shenyang Institute of Geology and Mineral Resources, China Geological Survey, Shenyang 110034, Liaoning, China

Keywords:: amphibolite series; subduction-accretionary complex; geochemistry; zircon; U-Pb age; calc-alkaline series; island arc tectonic environment

摘要:: 德言其庙斜长角闪岩系位于内蒙古中部温都尔庙地区以东，构造位置处于华北板块北缘温都尔庙俯冲-增生杂岩带内。对德言其庙斜长角闪岩系进行了地球化学分析和锆石SHRIMP U-Pb定年。结果表明：斜长角闪岩系SiO₂质量分数为51.62%~55.60%，Al₂O₃为16.45%~17.78%，全碱质量分数(4.5%~5.12%)较低；斜长角闪岩系具有钙碱性系列岩石地球化学特征，原岩为辉长质和辉长闪长质侵入岩；锆石n(²⁰⁶Pb)/n(²³⁸U)年龄加权平均值为(490.3±4.6)Ma；岩石富集轻稀土元素，轻、重稀土元素质量分数比值为5.93~7.73，Eu异常(0.84~1.05)不明显，具有明显的Nb、Ta负异常及Ti、P亏损，显示出其原岩具有消减带岩浆的特征，形成于岛弧构造环境。

Abstract:: Deyanqimiao amphibolite series is located in the eastern of Ondor Sum area, the central of Inner Mongolia. The structural location is in Ondor Sum subduction-accretionary complex zone, the northern margin of North China Plate. Geochemical characteristics and SHRIMP zircon U-Pb dating of Deyanqimiao amphibolite series were analyzed.The results show that mass fractions of SiO₂ of amphibolite series are 51.62%-55.60%, those of Al₂O₃ are 16.45%-17.78%, total alkali mass fractions are low, reaching 4.50%-5.12%; amphibolite series has the alc-alkaline series geochemical characteristics, and the original rock is gabbroic and gabbro-dioritic intrusive; zircon n(²⁰⁶Pb)/n(²³⁸U) weighted average age is (490.3±4.6)Ma; light rare earth element is rich in amphibolite with on Eu anomaly (0.84-1.05), the ratios of mass fractions of light and heavy rare earth elements are 5.93-7.73; amphibolite has Nb, Ta obvious negative anomaly and Ti, P loss, so that the original rock has the characteristics of subduction belt magma, and forms in island arc tectonic environment.