| 埃塞俄比亚施瑞地区花岗岩地球化学特征及构造环境 |
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| 引用本文： | 韩世礼,张术根,柳建新,丁 俊,张文山.埃塞俄比亚施瑞地区花岗岩地球化学特征及构造环境[J].地球科学,2014,39(1):10-20. |
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| 作者姓名： | 韩世礼 张术根 柳建新 丁 俊 张文山 |
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| 作者单位： | 1.南华大学核资源工程学院, 湖南衡阳 421001 |
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| 基金项目： | 国家自然科学基金项目411741032010年国外矿产资源风险勘查专项资金项目管理财[2010]211号 |
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| 摘 要： | 埃塞俄比亚北部施瑞地区具有造山前、造山期和造山后3种花岗岩类型, 全岩Sm-Nd等时线测年结果表明, 造山前和造山后花岗岩成岩年龄分别为824.4±15.5 Ma和517.9±5.8 Ma.3类花岗岩主量元素和稀土微量元素成分存在明显差异, 其中造山前花岗岩属于低钾过铝质花岗岩, 稀土分配模式属轻稀土弱富集型, 富集大离子亲石元素, 亏损P和Ti高场强元素；造山期花岗岩为准铝质高钾钙碱性花岗岩, 稀土分配模式属轻稀土富集型, 富集大离子亲石元素和高场强元素；造山后花岗岩为弱过铝质高钾钙碱性花岗岩, 稀土分配模式具强烈铕亏损的海鸥型, 富集大离子亲石元素, 明显亏损P和Ti高场强元素.综合研究表明: 造山前和造山期花岗岩均为I型幔源花岗岩, 构造环境处于被动大陆边缘-火山岛弧环境；造山后花岗岩为A2型壳源主花岗岩, 是在洋盆关闭和阿拉伯-努比亚地盾成熟后, 由减薄的地壳部分熔融产生.
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| 关 键 词： | 花岗岩 地球化学 构造 Sm-Nd同位素 埃塞俄比亚 施瑞 |
| 收稿时间： | 2013-07-23 |
Geochemistry and Tectonic Setting of Granites from Shire Region,Ethiopia |
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| Abstract: | There are pre-, syn-, and post-orogenic granites in Shire region of northern Ethiopia. Whole rock Sm-Nd isochron dating results show that diagenetic age of pre-, and post-orogenic ages are 824.4±15.5 Ma and 517.9±5.8 Ma respectively. Major, rare-earth and trace elements of three kinds of granite are obviously different. The pre-orogenic granites are relatively low in MgO and high in SiO2, belonging to the peraluminous series granite, with low K content and slight light REE enrichment, high large-ion lithophile element abundance and relative depletion of HFSE. The syn-orogenic granite belongs to the quasi-aluminous rock and high-potassium calc-alkaline granite, with the light REE enriched pattern, high large-ion lithophile element and HFSE abundances. The post-orogenic granite belongs to the weakly peraluminous high-potassium calc-alkaline granite, which has the chondrite-normalized REE patterns in the type of "gull" with severe depletion in Eu. The large-ion lithophile elements are concentrated, while P and Ti are severely depleted here. Comprehensive study shows both the pre- and syn-orogenic granites are I-type mantle-source granites in the passive continental margin-volcanic island arc tectonic setting; the post-orogenic granites are A2-type crust-source major granites, which were formed from the melting of thinner crust after the closure of oceanic basins and the growth of Arabian-Nubian shield. |
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