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中国大陆地壳铅同位素演化的动力学模型
引用本文:李龙,郑永飞,等.中国大陆地壳铅同位素演化的动力学模型[J].岩石学报,2001,17(1):61-68.
作者姓名:李龙  郑永飞
作者单位:中国科学技术大学地球和空间科学系化学地球动力学研究实验室,
基金项目:中国科学院知识创新工程项目(KZCX2107)和国家科技部重点基础研究发展规划项目(G1999 075503)资助成果.
摘    要:根据中国大陆中、新生代花岗岩长铅同位素数据库,沿用“铅构造模型”的基本思想并作部分改进,建立了中国大陆地壳铅同位素的动力学演化模型。与全球平均的铅同位素演化曲线相比,中国大陆地壳的原始物质相对较贫铀富钍,并且中国大陆的上地壳和下地壳在演化过程中分异得更加彻底。将本模型应用于大别地区中生代花岗岩长石铅同位素数据,结果发现它们具有壳幔铅混合的特征,并且以上下地壳物质混合产生的类地幔铅为主,花岗岩源岩中含有较高的富Th下地壳组分。

关 键 词:铅同位素  动力学演化模型  中国大陆  上地壳  下地壳  地幔  花岗石
修稿时间:2000年8月21日

Dynamic model for Pb isotope evolution in the continental crust of China.
LI Long,ZHENG YongFei and ZHOU JianBo.Laboratory for Chemical Geodynamics.Dynamic model for Pb isotope evolution in the continental crust of China.[J].Acta Petrologica Sinica,2001,17(1):61-68.
Authors:LI Long  ZHENG YongFei and ZHOU JianBoLaboratory for Chemical Geodynamics
Institution:LI Long,ZHENG YongFei and ZHOU JianBo.Laboratory for Chemical Geodynamics,Department of Earth and Space Sciences,University of Science and Technology of Chin,Hefei,China
Abstract:A dynamic model of Pb isotope evolution has been established for the continental crust of China in terms of a modification to "plumbotectonics" with the constraints from the Pb isotopic ratios of feldspars in China Mesozoic Cenozoic granites. Comparing with the evolutionary curves of Pb isotopes for the mean earth,the continental crust in China is characterized by U depletion and Th enrichment and by more compelete differentiation between the upper crust and the lower crust. As a case example,Pb isotopic data for feldspars in the granites of the Dabie Mountains are tested for the dynamic model. The results show that the Pb isotopic data suggest a mixing between the crust and the mantle in different proportions. The Dabie granites could be derived from a mixing between the upper crust and the lower crust,and thus exhibit mantle like Pb isotopic feature on the one hand,and contain higher proportions of the Th rich lower crust component on the other hand.
Keywords:Pb isotopes  Dynamic evolution  Continent of China  Upper crust  Lower crust  Mantle
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