赣北元古代变质沉积岩的铅钕同位素特征

Pb, Nd isotopic study of Proterozoic metamorphic sediments in North Jiangxi and its tectonic significance

赣北地区元古代变质沉积岩的铅、钕同位素研究结果表明,它们与扬子古陆南缘其他元古代地层非常相似,表明它们具有相似的成岩物质来源及构造演化历史。研究结果还显示,双桥山群变质泥质岩的PbPb等时线年龄为(1490±68)Ma,而障公山群、双桥山群、程浪群和修水群的钕模式年龄分别为1.57Ga、1.89Ga、1.77Ga和1.60Ga,均分布在1.5～1.9Ga之间,表明这些地层的形成年龄应小于1.9Ga,是中—晚元古代的产物,同时表明扬子古陆南缘存在古元古代的基底。

Nd, Pb isotopic study of metamorphic sediments of Zhanggongshan Group, Shuangqiaoshan Group, Chenglang Group and Xiushui Group in North Jiangxi shows that the components of Nd and Pb are identical to those of Proterozoic strata from southern margin of the Yangtze block, indicating that they have the same source and tectonic evolution history. The Pb Pb isochron of metamorphic argillite in Shuangqiaoshan Group is 1 490±68 Ma, while the Nd mode ages of Zhanggongshan Group, Shuangqiaoshan Group, Chenglang Group and Xiushui Group are 1.57 Ga, 1.89 Ga, 1.77 Ga, 1.60 Ga,respectively, less than 1.6-1.9 Ga, which suggest that they formed in Middle Proterozoic Subera.