| 安徽庐枞中生代火山岩系的特征及其形成的构造背景 |
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| 引用本文： | 孙冶东,杨荣勇.安徽庐枞中生代火山岩系的特征及其形成的构造背景[J].岩石学报,1994,10(1):94-103. |
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| 作者姓名： | 孙冶东 杨荣勇 |
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| 作者单位： | 南京大学地球科学系 |
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| 摘 要： | 庐枞地区中生代火山岩素是一套由粗面玄武岩－玄武粗安岩－粗安岩－粗面岩组成的岩石组合。岩石硅近饱和，全碱含量（尤其是Ｋ２Ｏ）高，Ｋ２Ｏ／Ｎａ２Ｏ、Ｆｅ２Ｏ３／ＦｅＯ比值大，Ａｌ２Ｏ３含量高且变化大，ＴｉＯ２含量低，富集Ｒｂ、Ｓｒ、Ｂａ、Ｚｒ、Ｔｈ、Ｕ和ＬＲＥＥ等元素，稀土配分为轻稀土富集型，锶、铅、氧等同位素显示了岩浆的幔源特征。本文通过详细的岩石化学和地球化学的对比研究，认为庐枞中生代火山岩系属于橄榄玄粗岩系，它形成于活动大陆边缘由挤压作用向引张作用转变的过渡时期，是火山弧后拉张形成的前裂谷阶段的产物。
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| 关 键 词： | 庐枞地区，火山岩，地球化学，稀土元素，构造背景 |
DISCUSSION ON THE CHARACTERISTICS AND TECTONIC SETTING OF THE MESOZOIC VOLCANIC SEQUENCES IN LUJIANG-ZONGYANG AREA |
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| Sun Yedong,Yang Rongyong,Ren Qijiang and Liu Xiaoshan.DISCUSSION ON THE CHARACTERISTICS AND TECTONIC SETTING OF THE MESOZOIC VOLCANIC SEQUENCES IN LUJIANG-ZONGYANG AREA[J].Acta Petrologica Sinica,1994,10(1):94-103. |
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| Authors: | Sun Yedong Yang Rongyong Ren Qijiang and Liu Xiaoshan |
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| Abstract: | An intensive volcanic activity took place in Lujiang-Zongyang volcanic basin during J3 K1. The volcanic rocks consist of trachytic basalt, basaltic latite, latite and trachyte. The characteristics of this volcanic sequence are: low TiO2 and silica saturation, high alkalis, high K2O/Na2O value and Fe2O3/FeO value, high and variable Al2O3, enrichment in Rb, Sr, Ba, Zr, U, Th and LREE. Sr, Ph and O isotopes indicate that the primary magmas of this volcanic sequence were derived from the upper mantle. Therefore, it is deemed to the shoshonite series.According to the analyses of geodynamic situation for generate potassic to ultrapotassic magmas, it is considered that they are products of extensional igneous activity. They are also characterized by generating at the transitional stage between extrusion to extensioll.Although the alkaline rocks occurred in Early Cretaceous Period, the Yangzi valley was not typical continental rift at that time. After the late stage of Early Cretaceous, as the subdue non zone moved backward and the rate of subduction slowed down, further extension evolved the volcanic arcs and the intracontinental rift ernergecl and developed in East China. |
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| Keywords: | Luzong area shoshonite series geochemistry rare earth element tectonic setting |
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