Abstract:地球化学研究表明,大蒲柴河岩体具有典型的埃达克岩特征,来自加厚下地壳的部分熔融作用.本文采用激光等离子质谱对该岩体进行了U-Pb同位素定年,结果表明该岩体为晚侏罗世(165Ma)岩浆活动的产物.锆石的LA-MC-ICPMS Hf同位素研究结果显示,e_(Hf)(165Ma)范围为-5.02~5.43,二阶段Hf模式年龄(t_(DM2))范围为965~1622Ma,暗示原始母岩浆为两种不同源区岩浆的...地球化学研究表明,大蒲柴河岩体具有典型的埃达克岩特征,来自加厚下地壳的部分熔融作用.本文采用激光等离子质谱对该岩体进行了U-Pb同位素定年,结果表明该岩体为晚侏罗世(165Ma)岩浆活动的产物.锆石的LA-MC-ICPMS Hf同位素研究结果显示,e_(Hf)(165Ma)范围为-5.02~5.43,二阶段Hf模式年龄(t_(DM2))范围为965~1622Ma,暗示原始母岩浆为两种不同源区岩浆的混合.另外,Hf同位素研究表明,研究区在中-新元古代时(965~1304Ma)曾经历了一次重要的地壳增生事件. Abstract: Based on geochemical evidence, the quartz diorites from Dapuchai, eastern Jilin Province, belong to typical adakites derived from partial melting of thickened lower crust. Zircon U-Pb dating by LA-ICPMS technique indicates that the studied plutons were emplaced during Late Jurassic with an age of 164.9 ± 0.8Ma. Zircon Hf analyses conducted by LA-MC-ICPMS show that these adakites have variational e_(Hf) (165Ma)values from -5.02 to 5.43, and Hf model ages from 965Ma to 1622Ma, indicating that the primary magma of the adakites originated from mixing of two different magma, one from partial melting of pre-existing crustal source that was separated from a depleted mantle source during the Middle Proterozoic; While the other magma from asthenospheric mantle through underplating during 985 ~ 1304Ma, indicative of an important crustal growth beneath the studied area.Read More
Publication Year: 2009
Publication Date: 2009-01-01
Language: en
Type: article
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