| 廖铸敏,曾禹人,白培荣,黄建国,李月森.西藏班公湖—怒江结合带中段恐弄拉地区辉长岩特征及其地质意义[J].贵州地质,2017,34(4):273-279,299 |
| 西藏班公湖—怒江结合带中段恐弄拉地区辉长岩特征及其地质意义 |
| Geological Characteristics and Its Significance of Gabbro in the Middle Bangonghu-Nu River Suture Belt，Kongnongla Area，Tibet |
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| DOI： |
| 中文关键词: 锆石U-Pb 中侏罗世 地球化学 恐弄拉 西藏 |
| 英文关键词:Zircon U-Pb Middle Jurassic Geochemistry Kongnongla Tibet |
| 基金项目:中国地质调查局项目《西藏恐弄拉1∶5万四幅区域地质调查》（编号：12120114062301）资助。 |
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| 中文摘要: |
| 通过对恐弄拉地区马前蛇绿混杂岩中辉长岩进行岩石学、地球化学等特征的研究，明确其属副长石辉长岩、钾玄岩系列；大离子亲石元素中Rb、K、P相对富集，Th、Sr亏损，高场强元素中Nb、Ta富集，而Zr、Hf相对亏损，岩浆源为富集型地幔，熔融程度较高，根据TiO2/10-MnO-P2O5构造环境判别图解，岩石形成于洋岛环境下。采用LA-MC-ICP-MS技术获得锆石U-Pb同位素年龄为166.9±2.5 Ma（n=16，MSWD=3.4）。笔者认为恐弄拉地区的辉长岩是中侏罗世中期（巴通期）怒江洋盆加速萎缩、俯冲带附近地幔活动强烈、洋壳向南侧冈底斯地块俯冲加剧时洋岛碱性玄武岩浆活动的产物。 |
| 英文摘要: |
| By study the Ophiolitic Melange about petrological and geochemical characteristics in Kongnongla area，it indicated that this kind of gabbro belong to plagioclase gabbro and K-feldspar series.The characteristics of the rock are：the Rb，K and P in large ion stone elements are relative lacked，Zr and Hf are relatively deficient，the magma source is enriched mantle with higher melting degree.According to the tectonic discrimination diagram for gabbro TiO2/10-MnO-P2O5，rocks are formed under the environment fo Yuyang island.The U-Pb isotopic age of zircons obtained by LA-MC-ICP-MS is 166.9±2.5 Ma（n=16，MSWD=3.4）.The research shows that the gabbro in Kongnongla area were producted by Nu river basin accelerated atrophy，subduction zone near the mantle activity，strong oceanic crust to South Gangdese terrane subduction intensified ocean island alkaline magma activity in the middle Jurassic（Bathonian）. |
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