摘要
从内蒙古固阳 -武川地区的麻粒岩中 ,新近获得了 ( 2 648.5± 4 .6)Ma的单颗粒锆石U Pb不一致线上交点年龄和 2 673Ma2 0 7Pb /2 0 6Pb表面年龄 ,这是内蒙古地区 (包括晋冀蒙交界地区 )迄今获得的最大的锆石U -Pb年龄值 ,为华北陆台北缘 (西段 )麻粒岩相带的地壳演化研究提供了可靠的年代学依据。结合地质体之间的野外地质关系 ,对所获得的年龄信息进行了合理的地质解释 ,认为它代表研究区最后一次麻粒岩相变质作用的时代。同时探讨了后期岩浆作用、变形变质作用对测年数据地质解释的影响。
There is a suit of granulite-facies metamophic supracrustal rocks in Cunkongshan area, Guyang, Inner Mongolia, from which two sample have been collected. The metamorphic supracrustal rocks in Yangtaigou from which sample No.P7JD4-25 Was obtained occurred as enclave in tonalite-gneiss, and in Heilongdong from which sample No. HL-5 was collected occurred as massive enclave in charnockite-gneiss. The zircons from former No.P7JD4-25 yield an up intercept age of (2 503±20)Ma which is consistent with the age from tonalite-gneiss. And yet the zircons from No. HL-5 yield an up intercept age of (2 648.5±5)Ma、 a 207 Pb/ 206 Pb age of (2 673±8)Ma and other ages of (2 450～2 510)Ma, the former two were interpreted as the age of granulite-facies metamorphicl event, and the later has similar meaning with No. P7JD4-25's. The age of (2 648.5±5)Ma and a 207 Pb/ 206 Pb age of (2 673±8)Ma were the greatest age which have been obtained so far using the method of single zircon from west-central part of Inner mongolia (include northern Shanxi and west-northern Hebei). It is important for the research about the precambrian crustal evolution of margin of North China.
出处
《前寒武纪研究进展》
2001年第1期28-34,共7页
Progress in Precambrian Research
基金
国家地质大调查项目! (J4 .1.2 )
