中祁连地块东段元古宙基底地层格架讨论

A discussion on the Proterozoic stratigraphy framework in the basement of eastern section of the Mid Qilian Massif

摘要: 中祁连地块东段元古宙基底一般认为由3 套地层组成,即古元古代湟源群、中元古代长城系湟中群和蓟县系花石山群,三者之间皆为平行不整合关系。但新的研究表明:(1) 花石山群与下伏的湟源群为角度不整合,结合新近发现的化石资料分析,认为花石山群是震旦纪—寒武纪稳定盖层沉积,不应归于基底组成部分;(2) 湟源群与湟中群为同一构造层,统称湟源群。

Abstract: It is generally considered that the basement of the eastern part of Mid Qilian Massif consists of three stratigraphic sequences that are separated by parallel unconformable boundaries:the Paleoproterozoic Huangyuan Group,Mesoproterozoic Huangzhong Group and Huashishan Group.However,recent study suggest that(1)The Huashishan Group unconformably overlies the Huangyuan Group at angle,and paleontological data suggests that the Huashishan Group represents a stable sedimentary cover of Sinian to Cambrian age,rather than basement.(2)The Huangyuan Group and Huangzhong Group were formed in the same tectonic cycle and should be combined as Huangyuan Group.