武当群成岩年龄新资料兼讨论

基金项目:

天津地矿所、鄂西北地调所、河北地质学院专题研究队开展的定向基金

详细信息

NEW INFORMATION ON THE AGES OF THE WUDANG GROUP-WITH A DISCUSSION

摘要: 武当群现有同位素年龄资料４８件，但对这些测试成果地质意义的解释有些混乱。作者通过对武当群的所有年龄测定数据重新作了综合分析之后认为：１．变酸性火山岩的下限年龄大于１９００Ｍａ；２．单颗粒锆石获得郧西群年龄为１５２７Ｍａ，表明该群应相当于武当群中的上部地层；３．变基性火山岩年龄大于１７００Ｍａ；４．变沉积岩的底界年龄小于１２５０Ｍａ；５．变火山岩的年龄间隔在１９００─１２００Ｍａ，而变沉积岩的年龄时限为１０００─８００Ｍａ。

Abstract: More than 40 isotopic age data of the Wudang Group are available now but their interpertations are somewhat confusing.The authors analyzed and interpreted again all the age data in the Group using some new dating methods. The integrated analysis indicates the ’following:（1）the lower limit of the ages of the meta-acid volcanic rocks should be older than 1900 Ma;（2）the single-zircon age of the Yunxi Group is 1527 Ma,which suggests that the Yunxi Group should belong to the upper part of the Wudang Group;（3）the age of meta-basic volcanic rocks should be younger than 1700 Ma 1（4）the age of the base of metasedimentary rocks is less than 1250 Ma; （5）the age range of meta-volcanic rocks is 1900-1200 Ma and the age range of metasedimentary rocks is about 1200-800 Ma.