大陆溢流玄武岩的地球化学特征及起源

张鸿翔; 徐志方; 马英军; 刘丛强

大陆溢流玄武岩的地球化学特征及起源

中国科学院地质与地球物理研究所, 北京 100101

基金项目:

国家攀登计划预选项目 95-预-39

详细信息

作者简介:
张鸿翔(1972), 男, 1996年毕业于中国地质大学, 现为中科院地质与地球物理研究所在职博士生, 从事地幔地球化学研究

中图分类号: P597
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- 被引次数: 0
出版历程
- 收稿日期: 2000-12-12
- 刊出日期: 2001-05-25

GEOCHEMICAL FEATURES AND ORIGIN OF CONTINENTAL FLOOD BASALTS

Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100101, China

摘要

摘要: 快速上涌的大陆溢流玄武岩(CFB), 与大陆裂开存在密切的成因联系.CFB总体岩石及地球化学成分均一, 富集同位素及不相容元素, 但一些样品含有明显的亏损成分, 反映出普遍的地幔不均一性.来自上下地幔边界及软流圈的地幔柱提供了CFB所需的主要物质和能量来源, 地壳混染作用对CFB的成分影响不大, 而受俯冲带脱水流体以及热地幔柱自身与围岩发生的交代作用影响.交代岩石圈地幔对CFB产生重要影响, 很好地解释了CFB所具备的微量元素和同位素特征.
- 大陆溢流玄武岩(CFB) /
- 大陆裂开 /
- 大陆岩石圈地幔(CLM) /
- 地幔柱 /
- 交代作用
Abstract: A close genetic relationship is present between the rapidly upwelling continental flood basalts(CFB)and the continent rift. On the whole, the petrologic and geochemical compositions are homogeneous and enriched with isotopes and incompatible trace elements. However, some samples contain conspicuous depleted compositions, reflecting a general mantle heterogeneity. The mantle plume originating from upper/lower mantle boundary or asthenosphere might have served as the major materials and energies required for CFB that has not been fully assimilated by the crust. The metasomatism between the dehydrated fluid in the subduction zone or the thermal mantle plume itself and its wall rocks determines that the metasomatic lithosphere mantle with a great effect on the formation of CFB, is a major cause of the trace elements and isotope characteristics of CFB.
- continental flood basalt(CFB) /
- continent rift /
- continent lithosphere mantle(CLM) /
- mantle plume /
- metasomatism

HTML全文

图 1 世界范围主要的CFB分布

Fig. 1. Distribution map of major continental flood basalts in world

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图 2 CFB的w(TiO₂)-w(Zr)图解

Fig. 2. w(TiO₂)-w(Zr)diagram of continental flood basalts

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图 3 CFB的w(Alk)-w(SiO₂)图解

Fig. 3. w(Alk)-w(SiO₂)diagram of continental flood basalts

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图 4 CFB的w(Nb)/w(Y)-w(Zr)/w(TiO₂)图解

Fig. 4. w(Nb)/w(Y)-w(Zr)/w(TiO₂)diagram of continental flood basalts

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图 5 峨眉山玄武岩稀土元素球粒陨石标准化图解

Fig. 5. Chondrite-normalized pattern of REE of Emeishan basalt

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图 6 主要CFB的不相容元素原始地幔标准化图解

CFB(average)为所有参与统计的CFB样品的平均值, 由于分配样式的相似性, 其平均值可在总体上代表CFB的元素特征

Fig. 6. Primitive mantle-normalized pattern of incompatible elements of major continental flood basalts

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图 7 CFB的同位素相关图解

Fig. 7. Isotope relation diagram of continental flood basalts

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图 8 主要地质单元微量元素原始地幔标准化图解

CLM(average).大陆岩石圈地幔的平均值^[30]; N-MORB.正常大洋中脊玄武岩; CC.大陆地壳

Fig. 8. Primitive mantle-normalized pattern of incompatible elements of major geological units

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