【摘要】 根据中国大陆中、新生代花岗岩长石铅同位素数据库 ,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下地壳组分更多还原

【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.更多还原