摘要
济源地区中元古界大古石组作为华北克拉通南缘太古宙变质结晶基底之上的第一层碎屑岩沉积盖层,对应于中元古代哥伦比亚超大陆初始裂解阶段,具有重要的研究意义。在野外剖面实测的基础上,结合岩性岩相分析、镜下薄片观察、岩石粒度参数分析等方法对大古石组下段沉积环境及演化进行分析和探讨。结果表明:大古石组下段为一套砂岩-砂泥互层-泥岩夹粉砂岩的陆源碎屑沉积,垂向上呈下粗上细的二元结构;粒度概率累积曲线多呈两段式,反映出河流相的典型沉积特征;岩性岩相分析显示砂岩结构和成分成熟度较低,显示出近源堆积的特点;大古石组下段主要形成于裂谷初期的曲流河环境,以河床、堤岸和河漫亚相为主,同时发育了河床滞留沉积、边滩沉积、天然堤沉积和河漫滩沉积微相。济源地区中元古界大古石组下段沉积特征是对华北克拉通中元古代早期伸展裂解过程的响应,大古石组底部曲流河相向顶部湖泊相的发育特征,揭示了华北克拉通中元古代持续强化的裂解过程。该研究结果可为华北克拉通中元古代早期伸展裂解过程提供依据和实证。
The Mesoproterozoic Dagushi Formation in the Jiyuan area is the first clastic sedimentary caprock on the Archean metamorphic crystalline basement in the southern margin of the North China Craton.It corresponds to the initial cleavage stage of the Mesoproterozoic Colombian supercontinent and has important research significance.On the basis of field profile measurement, combined with the field work, lithology and lithofacies analysis, thin section observation under microscope, and parameter analysis of rock particles, the sedimentary facies and evolution of the lower segment of Dagushi Formation were analyzed and discussed, The results showed that:(1)The lower segment of Dagushi Formation is a set of terrigenous clastic deposits of sandstone-sand-mud interbedded-mudstone intercalated with siltstone, which vertically presents a binary structure of coarse at the bottom and fine at the top;(2)The probability accumulation curve of grain size is two-stage, which reflects the typical sedimentary characteristics of fluvial facies;(3)The analysis of lithology and lithofacies showed that the structure and composition maturity of the sandstone are low, implying the characteristics of near-source accumulation;(4)The lower segment of Dagushi Formation is mainly formed in the meandering river environment at the initial stage of the rift, which is mainly composed of riverbed, embankment and floodplain subfacies, at the same time, the microfacies of riverbed retention deposition, beach deposition, natural dike deposition and floodplain deposition are developed.The sedimentary characteristics of the lower segment of Dagushi Formation in Jiyuan area are in response to the early Mesoproterozoic extension and rupture process of the North China Craton.The development characteristics of the meandering river facies at the bottom of the dagushi formation to the lacustrine facies at the top revealed the continuous strengthening cracking process of the North China craton in the Middle Proterozoic.This study could provide evidence for the early Mesoproterozoic extensional cracking process of the North China Craton.
作者
韩菲
郑德顺
王昕
魏丹峰
HAN Fei;ZHENG Deshun;WANG Xin;WEI Danfeng(Institute of Resources and Environment,Henan Polytechnic University,Jiaozuo454000,Henan,China)
出处
《河南理工大学学报（自然科学版）》
CAS
北大核心
2021年第5期45-55,共11页
Journal of Henan Polytechnic University（Natural Science）
基金
国家自然科学基金资助项目(41872238)。
关键词
中元古界
熊耳群
大古石组
沉积相
济源地区
华北南缘
Mesoproterozoic
Xiong’er Group
Dagushi formation
sedimentary facies
Jiyuan area
southern margin of North China
