摘要
内蒙北部苏尼特右旗以北二道井、哈拉干和红格尔地区的含铁变质岩系中变质基性火山岩Sm-Nd全岩等时线年龄为1511±76Ma,这表明该岩系属中元古代而不是以往推测的早古生代。等时线的εNd(t)值为+6.3±1.7,属亏损型地幔源区。岩相学分析表明它形成于规模不大、具中等水深和较弱水动力条件的较封闭海域。据上述特征推测,华北板块北缘中段曾存在中元古代被动型火山陆缘。
Sm-Nd whole-rock data for the ferrian metamorphic series outcropping in northern Inner Mongolia define an isochron of 1151±76 Ma with εNd(t) = 6.3± 1.7. The age data provides the first evidence of the middle Proterozoic rather than the early Paleozoic as was deduced before. εNd(t) = 6.3 reveals that there would be a depleted mantle source. Sedimentary facies analysis suggests that the series formed in a semi-closed, intermediate-depth, small sea basin with volcanic materials and distal fragments which belongs to the Proterozoic passive volcanic continental margin in the middle segment of the northern margin of the North China plate.
出处
《地质论评》
CAS
CSCD
北大核心
1994年第4期307-311,共5页
Geological Review
基金
香港霍英东教育基金
关键词
变质岩
含铁
时代
构造环境
华北
Sm-Nd isotope, middle Proterozoic era, passive volcanic continental margin
