古华北地块前寒武纪地壳发展阶段及其时限确定

<正> 作者在参加了“辽吉地区前寒武纪研究”和“辽东晚前寒武纪”研究之后,获得了较丰富的放射性年龄资料,其中包括Rb-Sr年龄9组,U-Pb年龄18个和一批海绿石年龄,从而对辽吉地区前寒武纪地层柱的许多空白部分进行了地质年代学方面的较全面补充。其结果是使以辽东为代表的前寒武纪地层柱基本上为实测年龄数据所控制,成为我国前寒武纪各地块中时间剖面齐全,数据丰富的地区。对此我们已做了报道(王东方、王集源、

Developmental stages of the Precambrian crust and its time line in ancient North China Massive

Based on the study of the Precambrian strata and the Rb-Sr, U-Pb, Pb-Pb and glacu-conite K-Ar, all the developmental stages of the earth Crust in ancient North China Massif are analysed.The existence of an Early-Middle Archean earth core of 3700 to 3400 Ma BP is verified by using 12 Rb-Sr, U-Pb, Sm-Nd and Pb-Pb datings.4 Pb-Sr and glacuconite ages verify the existence of-the Sinian System of northern type, showing a correlation between the Changcheng Group and the Hutuo or Liaohe Group.5 thermal events (A-E) corresponding to 5 developmental stages (Qianxi, Anshan, Wutai, Changcheng and Nankou stages) are suggested.On the basis of the total 160 Rb-Sr, U-Pb, Pb-Pb, Sm-Nd and glacuconite K-Ar dating data, a Precambrian geological time scale is established and these boundary ages are shown to coincide essentially with the global structural events.