doi:10.16186/j.cnki.1673-9787.2020110077

Received:2020/11/25

Revised:2021/01/15

Published:2021/09/15

Analysis of sedimentary facies of the lower segment of Dagushi formation in Mesoproterozoic Xiong'er group in Jiyuan area， Henan province

HANFei , ZHENGDeshun , WANGXin , WEIDanfeng

Institute of Resources and Environment， Henan Polytechnic University， Jiaozuo 454000 ， Henan， China

Abstract: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 bot-tom 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 flood-plain 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.

Key words:Mesoproterozoic;Xiong'er Group;Dagushi formation;sedimentary facies;Jiyuan area;southern margin of North China

 河南济源地区中元古界熊耳群大古石组下段沉积相分析_韩菲.pdf