苏鲁超高压变质带东海青龙山高压正片麻岩中白云母的^(40)Ar/^(39)Ar年代学研究  

40^(40)Ar/^(39)Ar Chronological Study of the Muscovite from Qinglongshan High -Pressure Orthogneiss, Donghai County, Su-Lu UHP-Metamorphic Belt

作　　者：陈文[1] 李曙光[2] 张彦[1] 刘新宇[1] 

机构地区：[1]中国地质科学院地质研究所 [2]中国科学技术大学,合肥230026

出　　处：《地质论评》2003年第5期537-543,共7页Geological Review

基　　金：国家自然科学基金(编号49973003);国土资源大调查项目(编号2000020190118);国家重点基础发展规划项目(编号G1999075503)

摘　　要：作为东海青龙山榴辉岩围岩的高压变质的正片麻岩,其白云母的常规^(40)Ar/^(39)Ar年龄和Rb-Sr、Sm-Nd年龄一致,激光微区Ar同位素分析表明,白云母的Ar同位素分布也是均匀的。由此得出的初步结论是:①高压变质的正片麻岩中的白云母中不含过剩Ar,这类矿物可以作为^(40)Ar/^(39)Ar同位素测年的对象;②青龙山榴辉岩中的白云母含大量过剩氩,而作为其围岩的超高压正片麻岩中的白云母却不含过剩氩,这一事实证明了榴辉岩中白云母的过剩氩不是来自围岩,而是榴辉岩自身继承的。The conventional 40Ar/39Ar age of muscovite in high-pressure metamorphic orthogneiss, surrounding rocks of the Qinglongshan eclogite, is identical with its Rb-Sr and Sm-Nd ages. The Laser microprobe analysis shows that the argon isotope is evenly distributed in the muscovite. The preliminary conclusion is (1) muscovite in high-pressure metamorphic orthogneiss does not contain excess argon and can be the object for 40Ar/39Ar dating; (2) muscovite in the Qinglongshan eclogite contains large amounts of excess argon while muscovite in its surrounding rocks, i. e. high-pressure orthogneiss, does not contain excess argon. This fact proves that the excess argon of muscovite in eclogite does not come from its country rocks but from its inheritance.

关 键 词：正片麻岩 高压白云母 过剩氩 超高压变质带 东海青龙山 同位素年代学 

分 类 号：P588.3[天文地球—岩石学]