大别造山带南部浅变质岩的锆石U-Pb年龄  

The Zircon U-Pb Ages of the Low-grade Metamorphic Rocks in the Southern Part of Dabie Mountain,China

作　　者：谢智[1] 陈江峰[1] 董树文[2] 李惠民[3] 周泰禧[1] 左义成[3] 周红英[3] 

机构地区：[1]中国科学技术大学地球和空间科学系 [2]中国地质科学院 [3]天津地质矿产研究所

出　　处：《地球学报（中国地质科学院院报）》1999年第4期335-340,共6页Acta Geoscientia Sinica

基　　金：国土资源部同位素地质研究开放实验室资助;国家自然科学基金

摘　　要：在大别造山带南部,出露与超高压榴辉岩伴生,仅经过绿片岩相变质作用的浅变质岩。浅变质岩的锆石U- Pb 年龄表明,其原岩形成时代为晋宁早期(1100 ±140 Ma) ,与扬子地块南缘的一些岩浆岩的年龄相似。浅变质岩不一致线下交点年龄及超高压地块区域片麻岩的锆石测定结果表明,它们均受到加里东期构造热事件的影响,印支期超高压变质作用仅使浅变质岩的Rb- Sr 体系重置而没有影响到其U- Pb 体系。In the southern part of Dabie Mountain,the low_grade metamorphic (LM)rocks which underwent greenschist facies metamorphism are intercalated with ultrahigh pressure(UHP) eclogites.The zircon U_Pb dates show that the protolith of LM rocks was formed in the early Jinningian period(1100±140Ma),similar to the age of some magmatic rocks in the southern margin of the Yangtze block.The lower point age of zircon U_Pb discordia of LM rock and the date of regional gneiss in UHP block show that these two sorts of rocks were both affected by the thermal event in Caledonia.The Indosinian metamorphism reset the Rb_Sr system of LM rock,but did not affect the U_Pb system.

关 键 词：浅变质岩 锆石 晋宁早期 变质岩 铀-铅年龄 

分 类 号：P315.3[天文地球—地震学] P597[天文地球—固体地球物理学]