| 云南金平县镁铁-超镁铁岩岩床群的地球化学特征 |
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| 引用本文： | 徐平,贾秀琴.云南金平县镁铁-超镁铁岩岩床群的地球化学特征[J].地质科学,1999,34(2):233-241. |
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| 作者姓名： | 徐平 贾秀琴 |
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| 作者单位： | 1. 中国科学院地质研究所 北京 100029;2. 中国科学院高能物理研究所 北京 100080 |
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| 摘 要： | 金平地区的镁铁-超镁铁质岩岩床群侵入在晚泥盆世地层中。岩石类型包括粒玄岩、辉绿岩、辉长岩、橄榄辉玄岩和苦橄岩。岩床群的走向与区域构造方向一致,为北西向延伸。单个岩床的厚度在1-200m之间,较厚的岩床有明显的结晶分异作用。粒玄岩和辉绿岩含相当数量的钛铁矿,称为铁钛玄武岩。化学成分以强烈富Ti为特征,TiO2含量平均达3.9%.Mg含量通常较低,是拉斑质或碱性玄武岩演化而来的。这种高Ti玄武岩还富Th、Ta、Nb,Th/Ta比值接近1,Zr/Nb比值较低,接近OIB的特征,推测产于板内环境,是地幔柱部分熔融形成的岩浆。金平岩床群中苦橄岩和橄榄辉玄岩(MgO含量在15.1%-23.3%之间)出露的比例相对较多,指示地幔柱部分熔融的温度较高,推测相当于地幔柱尾部的特征。
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| 关 键 词： | 金平 镁铁-超镁铁岩 岩床群 地幔柱 |
| 收稿时间： | 1997-11-20 |
| 修稿时间： | 1997-11-20; |
THE GEOCHEMICAL CONSTRAINTS ON MAFIC-ULTRAMAFIC SILL SWARMS FROM JINPING AREA,YUNNAN |
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| Xu Ping Jia Xiuqing \ Zhang Qi Han Song \ Qian Qing Institute of Geology,Chinese Academy of Sciences,Beijing\ Institute of High Energy Physics,Chinese Academy of Sciences,Beijing\.THE GEOCHEMICAL CONSTRAINTS ON MAFIC-ULTRAMAFIC SILL SWARMS FROM JINPING AREA,YUNNAN[J].Chinese Journal of Geology,1999,34(2):233-241. |
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| Authors: | Xu Ping Jia Xiuqing \ Zhang Qi Han Song \ Qian Qing Institute of Geology Chinese Academy of Sciences Beijing\ Institute of High Energy Physics Chinese Academy of Sciences Beijing\ |
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| Institution: | 1. Institute of Geology, Chinese Academy of Sciences, Beijing, 100029;2. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100080 |
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| Abstract: | The mafic-ultramafic sill warms which intruded in later Devonian strate from Jinping area include dolerite、diabase、gabbro、ankaramite and picrite. The sill swarms stretch in the north-west direction and are concordant with that of regional tectonics. The thickness of sill varies from 1m to 200m. The crystallization differentiation can be observed clearly in some thicker sills. The dolerite and diabase bearing lots of ilmenite are called Fe-Ti basalts and are characterized by high Ti content which the average TiO2 abundance can go up to 3.9% in composi tion of dolerite and diabase and by low Mg’ number. The evidence of geochemistry show that these two basalts are developed by tholeiite or alkaline basalt. In addition to high Ti, The dolerite and diabase also show high abundance of Th、Ta 、Nb. The value of Th/Ta is 1 approximately and Zr/Nb is low comparing to N-MORB. So these two basalts show the feature of OIB and may be originated from partial melting of mantle plume in intralplate. The are more exposure of picrite and anka ramite (15.1%-23.3% MgO) in Jinping than that around area suggests that the temperature of partial melting of mantle plume be high comparatively and the source reservoir of mafic-ultramafic sill warms in Jinping area may be in the tail of mantle plume. |
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| Keywords: | Jinping Mafic-ultramafic Sill swarms Mantle plume |
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