苏皖北部上元古界划分与对比的探讨

A DISCUSSION ON DIVISION AND CORRELATION OF THE UPPER PROTEROZOIC IN NORTHERN JIANGSU AND ANHUJ PROVINCES

本文首次对苏皖北部地区上元古界中已有K-Ar同位素年龄出现的分散及“倒置”现象的原因作了探讨,指出大多数K-Ar年龄由多种因素造成Ar丢失,从而导致不同程度的偏新。因此,这些年龄数据不能代表本区晚元古代沉积岩的真实年龄。作者根据近几年新获得的一些Rb-Sr全岩等时线年龄数据及地壳波浪运动中表现出来的周期性特征,讨论了建立“徐淮系”的可能性及必要性。作者认为,“徐淮系”可以填补青白口系与震旦系之间至少150Ma的沉积缺失。

This paper, for the first time, discusses the reasons for discordance and 'reverse' phenomenon of the K-Ar ages obtained from the upper Proterzoic in northern Jiangsu and Anhui provinces.lt is evident that most of the K-Ai ages are yunger than the true ages of the rocks.These ages,therefore, cannot represent the true ages of sedimentary rocks in this region. According to the newly obtained Rb-Sr isotopic ages and periodicity of crustal wavy motion, the authors discuss the possibility and necessity of estabishing the 'Xuhuai System' , which could fulfil the lacuna ( about 150Ma ) between the Qingbaikou and Sinian Systems.