摘要
提供了苏鲁超高压变质带南部震旦纪浅变质千枚岩的全岩Rb Sr同位素年龄测试数据 ,获得了 2 2 1± 14Ma的等时线年龄。对测试结果的分析认为 :该年龄为浅变质岩的变质年龄。区域调查对比表明 ,低绿片岩相变质作用在造山带组成岩石中普遍存在 ,并叠加于超高压变质岩石 ,因而上述年龄代表在印支期存在普遍的退变质作用年龄。浅变质岩中印支期同位素年龄的获得 ,对正确认识超高压变质带的演化具有重要意义。
Sulu ultrahigh-pressure metamorphic belt is world known for the exposures of large volumes of high-pressure and ultrahigh-pressure metamorphic rocks.A great deal has been conducted by a great number of geologists both home and abroad and research results of world attention have been achieved.The testing data is offered in the text for the whole rock Rb-Sr isotopic age of Sinian epimetamorphic phyllite in the south Sulu UHP metamorphic belt,and the isochronal data of 221±14Ma is determined.The analysis results are deemed that the isotopic age is metamorphic age of epimetamorphic rocks.The regional survey contrast reveals that the metamorphism of low-greenschist facies occurs widely in all kinds of rocks of Sulu orogenic belt,and overlapped above the ultrahigh-pressure metamorphic rocks.Therefore,the above isotopic age representatives behave a general regressive metamorphic age in Indo-Chinese epoch.It is concluded that the isotopic age of epimetamorphic rocks in Indo-Chinese epoch is of important significance to a correct knowledge of the evolution of the UHP metamorphic belt.
出处
《江苏地质》
2004年第3期140-144,共5页
Jiangsu Geology
