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

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

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.