| 杭州南部新元古代双峰式火山岩的厘定及其构造意义 |
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| 引用本文： | 卢成忠,顾明光.杭州南部新元古代双峰式火山岩的厘定及其构造意义[J].中国地质,2007,34(4):565-571. |
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| 作者姓名： | 卢成忠 顾明光 |
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| 作者单位： | 浙江省地质调查院,浙江,杭州,311203 |
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| 基金项目： | 中国地质调查局地质调查项目 |
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| 摘 要： | 杭州南部新元古界青白口系上墅组火山岩,由基性岩和酸性岩组成,缺乏SiO2在57×10-2～68×10-2的中性及中酸性成分,构成一套双峰式火山岩组合。基性火山岩与酸性火山岩的稀土元素和微量元素特征存在明显差异,表明酸性火山岩并不是由基性岩浆分离结晶产生,而是分别由不同的源区熔融形成,基性火山岩起源于亏损程度较低的地幔或来源于亏损地幔的岩浆受到陆壳物质的混染,酸性火山岩主要由上地壳经不同程度的部分熔融而形成,其形成的构造环境为陆内至陆缘张裂环境。上墅组双峰式火山岩的形成,是华南Rodinia超大陆裂解事件的岩石学记录,揭示了华南Rodinia超大陆裂解始于青白口纪。
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| 关 键 词： | 新元古代 双峰式火山岩 上墅组 构造环境 Rodinia超大陆裂解 杭州南部 |
| 文章编号： | 1000-3657（2007）-0565-07 |
| 修稿时间： | 2006-11-02 |
Definition of Neoproterozoic bimodal volcanic rocks in the south of Hangzhou and its tectonic significance |
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| LU Cheng-zhong,GU Ming-guang.Definition of Neoproterozoic bimodal volcanic rocks in the south of Hangzhou and its tectonic significance[J].Chinese Geology,2007,34(4):565-571. |
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| Authors: | LU Cheng-zhong GU Ming-guang |
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| Institution: | Zhejiang Institute of Geological Survey, Hangzhou 311203, Zhejiang, China |
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| Abstract: | Volcanic rocks of the Neoproterozoic Qingbaikouan Shangshu Formation in southern Hangzhou are composed of basic and acid rocks,while rocks of intermediate and intermediate-acid compositions with 57%-68% SiO2 are lacking. They form a bimodal volcanic rock association. There are evident differences in trace elements and rare earth elements (REE) between the basic and acid volcanic rocks,which indicates that the acid volcanic rocks were not produced by fractional crystallization of basic magma but formed by melting of different sources. The basic volcanic rocks originated from the less-depleted mantle or from magma of the depleted mantle contaminated with crustal material. The acid volcanic rocks mainly formed by different degrees of partial fusion of upper crust in an intracontinental to continental-margin extensional environment. The formation of the bimodal volcanic rocks in the Shangshu Formation is a petrological record of the breakup event of the supercontinent Rodinia in South China,which reveals that the breakup of the supercontinent Rodinia in South China started in the Qingbaikouan Period. |
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| Keywords: | Neoproterozoic bimodal volcanic rocks Shangshu Formation tectonic environment Rodinia supercontinent breakup southern Hangzhou |
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