登封群的定年及其划分问题的探讨  

A Discussion on the Classification and Dating of the Dengfeng Group

作　　者：薛良伟[1] 张天义 徐莉[1] 卢欣祥 

机构地区：[1]中国地质大学(北京)国土资源与高新技术研究中心,北京100083 [2]河南省地质科学研究所,河南郑州450053

出　　处：《地球学报》2004年第2期229-234,共6页Acta Geoscientica Sinica

基　　金：河南省科技重点攻关项目 (0 12 3 0 3 14 0 0 )资助

摘　　要：对登封群人们先后采用过K Ar、Rb Sr、U Pb、单颗粒锆石Pb Pb、Sm Nd等多种同位素定年方法。由于不同方法得到的结果差别很大 ,直接影响了对登封群的认识 ,因而对登封群出现了多种划分方案。本文综合分析后认为 ,登封群花岗 绿岩地体形成于新太古宙末期 (2 5 0 0～ 2 6 0 0Ma) ,难以划分出元古代的地层单元。另外 ,对已有的同位素测年成果使用上要结合样品的地质、地球化学特征进行具体分析 ,才能得出合理的解释。Different isotopic dating methods such as K-Ar,Rb-Sr,U-Pb (including the single grain zircon Pb-Pb dating) and Sm-Nd have been used to identify Denfeng Group.As different methods yield remarkably different dating results,there exist several schemes for classification of Dengfeng Group. Such a situation directly hinders the further study of Denfeng Group. Based on a comprehensive analysis,this paper holds that the granite-greenstone terrain of Dengfeng Group was formed at the end of Neoarchean (2 500～2 600 Ma),and that it is difficult to divide the stratigraphic units of Proterozoic.In addition,the results of isotopic dating should be used with care.In order to obtain a reasonable interpretation,the utilization of the isotopic dating results should be combined with a comprehensive analysis of the geological and geochemical characteristics of the samples.

关 键 词：同位素定年 新太古宙 登封群 华北克拉通 元古代 

分 类 号：P534.3[天文地球—古生物学与地层学]