| 摘要: |
| 对33 件采自东太平洋海隆(EPR)13°N 附近的玄武岩和火山玻璃样品进行了微量元素分析, 以探讨该区域玄武岩的演化过程和物质来源。测试分析结果显示所有样品的微量元素含量比值m(Tb)/m(Lu)(1.74～2.03), m(Sm)/m(Nd) (0.29～0.35)和m(Nd)/m(Y)(0.32～0.48)存在不能忽略的变化, 表明它们可能受到了非均一质地幔来源的影响。m(La)/m(Nb), m(La)/m(Sm)和m(La)的线性相关性辨别结果, 以及稀土元素分布型式图表现的元素分布特征等均表明东太平洋海隆13°N 附近的洋中脊玄武岩可能来自不同的端元组分, 也证明研究区域内的玄武岩除N-MORB(常规型MORB)外, 还有E-MORB(富集型MORB)。此外, 玄武岩m(Ce)/m(Pb)和m(Ce), m(Nb)/m(U)和m(Nb), 以及m(Nb)/m(La)和m(La)线性相关性, 均显示了这些微量元素比值和微量元素含量的正相关趋势, 这可能与双组分地幔熔融有关。m(Nb)/m(Th)和m(Th)线性相关性显示出负相关, 显示该区域玄武岩的地幔来源组成可能受到了富集组分的影响。分析显示, 样品的Nb*值均大于1, 而大部分样品的Ta*值大于1, 这表示大部分玄武岩的来源很可能是从俯冲区域循环的物质。 |
| 关键词: 东太平洋海隆(EPR) 洋中脊玄武岩 微量元素 |
| DOI：10.11759/hykx20121114002 |
| 分类号: |
| 基金项目:国家自然科学基金项目(40830849, 40976027, 40906029); 国家重点基础发展研究计划(013CB429700); 山东省自然科学杰出青年基金项目(JQ200913); 国家大洋重大专项课题(DY125-12-R-02, DY125-11-R-05) |
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| Characteristic of trace element in mid-ocean ridge basalts near the East Pacific Rise 13°N |
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| Abstract: |
| In this study 33 samples including basalts and glass near the East Pacific Rise (EPR) 13°N were analyzed to investigate the evolutionary process and material sources of basalts in this area. The trace elements ratios including m(Tb)/m(Lu) (1.74～2.03), m(Sm)/m(Nd) (0.29～0.35) and m(Nd)/m(Y) (0.32～0.48) in these samples show that the variations are limited but could not be ignored. It implies these basalts maybe influenced by heterogeneous mantle source. The trace elements ratios m(La)/m(Nb), the linear correlation plot of trace elements ratios m(La)/m(Sm) versus m(La) and REE distribution patterns of chondrite-nomalized basalt samples all show that MORB near EPR 13°N may have different end-members, demonstrating that the basalts near EPR 13°N include N-MORB and E-MORB. Meanwhile, the linear correlation plot of trace elements ratios m(Ce)/m(Pb) versus m(Ce), m(Nb)/m(U) versus m(Nb) and m(Nb)/m(La) versus m(La) all display positive trends. It means they have relationship with two end-members mantle melting. Linear correlation plot of trace elements ratios m(Nb)/m(Th) versus m(Th) displays negative trend, which implies there are enriched components involving in mantle source of basalts near EPR 13°N. The values of Nb* of all samples and Ta* of some samples are higer than 1, which demonstrate that mantle source of most MORBs are materials from subduction area. |
| Key words: the East Pacific Rise mid-ocean ridge basalt trace element |
