| 东天山早中生代侵入体地球化学特征及其构造意义 |
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| 引用本文： | 高志武,吕昶良,邓明国,管申进,杨富强.东天山早中生代侵入体地球化学特征及其构造意义[J].地球科学,2021,46(7):2287-2298. |
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| 作者姓名： | 高志武 吕昶良 邓明国 管申进 杨富强 |
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| 作者单位： | 遵义师范学院工学院,贵州遵义 563006;广西壮族自治区地球物理勘察院,广西柳州 545005;昆明理工大学国土资源工程学院,云南昆明 650093 |
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| 基金项目： | 国家自然科学基金项目41363001国家自然科学基金项目41762009遵义师范学院博士基金项目遵师BS[2019]44号 |
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| 摘 要： | 东天山百灵山西辉长岩、似斑状花岗岩近年来才被发现，为了解其成因及相关大地构造背景，对其进行地质学、地球化学、锆石U-Pb定年及Sr-Nd同位素分析.LA-ICP-MS锆石U-Pb测年结果显示，百灵山西辉长岩、似斑状花岗岩分别形成于236 Ma和228 Ma.辉长岩具有较低的SiO2（43.50%~46.03%）含量，较高的CaO（11.40%~13.24%）、Fe2O3T（9.62%~11.84%）和MgO（6.02%~10.58%；Mg#=53~69）含量以及Ce/Pb、Ti/Zr、Ti/Y及Ba/Th比值，且富集LREE、LILE，表明其形成于受板片脱水流体交代地幔楔的部分熔融.似斑状花岗岩表现出I型花岗岩的特征，且具有较高的SiO2（71.14%~72.71%），强富集LREE（La/Yb）N=12.61~28.45]和LILE（例如Rb，K和Pb），表明其形成于下地壳的部分熔融.而较高的Mg#（39~41）值、Ti/Y（154.40~306.18）比值，显示其源区有地幔物质的加入.结合前人研究成果，可知东天山地区在240 Ma以后已经进入陆内演化阶段，百灵山西辉长岩及似斑状花岗岩均形成于陆内环境.
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| 关 键 词： | 东天山 早中生代 百灵山西辉长岩 似斑状花岗岩 地球化学 |
| 收稿时间： | 2020-07-19 |
Geochemical Features and Tectonic Setting of the Mesozoic Intrusions in Eastern Tianshan |
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| Gao Zhiwu,Lü Changliang,Deng Mingguo,Guan Shenjin,Yang Fuqiang.Geochemical Features and Tectonic Setting of the Mesozoic Intrusions in Eastern Tianshan[J].Earth Science-Journal of China University of Geosciences,2021,46(7):2287-2298. |
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| Authors: | Gao Zhiwu Lü Changliang Deng Mingguo Guan Shenjin Yang Fuqiang |
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| Abstract: | The Early Mesozoic magmatism of the eastern Tianshan was just reported recently, the source and tectonic setting of which are poorly understood. Formed during the Early Mesozoic, the Bailingshanxi gabbro and porphyritic granite were recently discovered. In this study, new geochemistry, zircon U-Pb dating and whole-rock Sr-Nd isotope data are provided for these intrusions. Zircon LA-ICP-MS U-Pb dating results reveal that the gabbro and porphyritic granite emplaced at ca. 236 Ma and 228 Ma, respectively. The Bailingshanxi gabbro has low SiO2 (43.50%-46.03%) content, and high CaO (11.40%-13.24%), Fe2O3T(9.62%-11.84%) and MgO (6.02%-10.58%; Mg#=53-69) contents. Meanwhile, it is characterized by high Ce/Pb, Ti/Zr, Ti/Y and Ba/Th ratios, and rich in LREE and LILE (e.g., Ba and Sr), indicating the Bailingshanxi gabbro was originated from the partial melting of the metasomated mantle wedge. Showing high SiO2 (71.14%-72.71%), LREE ((La/Yb)N=12.61-28.45) and LILE (e.g., Rb, K and Pb), the Bailingshanxi porphyritic granite was likely derived from the partial melting of the lower crust. Additionally, it has high Mg# (39—-41) value and Ti/Y (154.40-306.18) ratios, implying mantle component played an important role in the formation of the porphyritic granite. Integrating with previous studies, the Eastern Tianshan is probably under inter-plat environment after 240 Ma, and the Bailignshanxi gabbro and porphyritic granite were formed during this stage. |
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