黔东南新元古代清水江组碎屑锆石U-Pb年代学研究及其地质意义  

DETRITAL ZIRCON U-Pb AGES OF THE NEOPROTEROZOIC QINGSHUIJIANG FORMATION IN SOUTHEASTERN GUIZHOU AND THEIR GEOLOGICAL SIGNIFICANCE

作　　者：魏亚楠[1,2,3] 江新胜[3] 崔晓庄[3] 卓皆文[3] 江卓斐[2,3] 蔡娟娟[1,2,3] 

机构地区：[1]中国地质科学院,北京100037 [2]中国地质大学地球科学与资源学院,北京100083 [3]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《矿物岩石》2015年第3期61-71,共11页Mineralogy and Petrology

基　　金：国家自然科学基金项目(41030315;41402103);中国地质调查局项目(12120114067901;1212011121105)

摘　　要：采用LA-ICP-MS方法,对黔东南雷山地区新元古代清水江组郎德剖面碎屑锆石进行U-Pb同位素测定,以建立清水江组碎屑锆石U-Pb年龄谱。从获得的56组单颗锆石有效U-Pb年龄结果反映,清水江组碎屑锆石U-Pb年龄主要分布区间为934 Ma^931Ma,855 Ma^847 Ma,827 Ma^825 Ma,805 Ma^798 Ma,785 Ma^776 Ma和767 Ma^763 Ma,最小年龄加权平均值为766 Ma,幕式分布特征明显,峰值突出,充分反映扬子陆块与华夏陆块拼合以来的构造岩浆热事件。U-Pb年龄谱对比结果表明,其U-Pb年龄谱与扬子西缘、扬子北缘U-Pb年龄谱基本一致,代表了扬子陆块的U-Pb年龄谱基本特征。U-Pb年龄谱相似性分析显示,扬子陆块与塔里木陆块亲缘关系密切,而与华北陆块关系疏远,与华夏陆块自1 000 Ma汇聚以来才开始有很好的亲缘性。LA-ICP-MS U-Pb isotopic age from the Neoproterozoic Qingshuijiang Formation in the southeast of Guizhou were made and 56 effective groups of single detrital grained zircon U-Pb ages were obtained. It shows that the detrital zircon ages are primary distributed in the range of 934 Ma-931 Ma,855 Ma-847 Ma,827 Ma-825 Ma,805 Ma-798 Ma,785 Ma-776 Ma and 767 Ma-763 Ma,with weighted mean minimum age of 766 Ma. The age distribution has a distinct episodic style with obvious peaks, fully reflecting the magmatic and tectonic events since the Yangtze and Cathaysian plates converged. It reveals that the U-Pb age spectrum is similar to that of the western margin and northern margin of Yangtze Block, basically representing the characteristics of U-Pb age spectrum of the Yangtze block. Analysis of U-Pb age spectrum similarity indicates that the Yangtze Block and Tarim Block have a close affinity while the Yangtze Block and the North China Block have a poor one. The close affinity between the Yangtze Block and Cathaysian Block only occurred when they collided since 1 000 Ma.

关 键 词：新元古代 清水江组 碎屑锆石 U-Pb年龄谱 

分 类 号：P597.3[天文地球—地球化学]