吉南地区万隆组燧石相微生物化石及其古环境意义  

Microoriganism fossils in cherts from the Wanlong Formation in southern Jilin Province and their paleoenvironmental significance

作　　者：张德军 刘鹏举[1] 尚晓冬[1] 杨犇[1] ZHANG Dejun;LIU Pengju;SHANG Xiaodong;YANG Ben(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Shenyang Center of Geological Survey,CGS,Shenyang,Liaoning 110034,China)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质调查局沈阳地质调查中心,辽宁沈阳110034

出　　处：《地质学报》2023年第12期4006-4019,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号U2244202);中国地质调查局沈阳地质调查中心(东北地质科技创新中心)主任基金项目(编号SJ202305);中国地质调查局项目(编号DD20230220)联合资助的成果。

摘　　要：拉伸纪作为承接中元古代蓝菌时代以及成冰纪生物锐减的关键地质历史时期,是探索早期生命与环境演化最重要的时期之一。吉林南部地区地处华北板块东北缘,拉伸系发育完整、出露全,在燧石条带、燧石结核和泥页岩中富含微生物化石,是开展拉伸纪古生物学、生物地层学和古环境研究的理想地区。本次工作利用岩石切片法在吉林南部二道江地区万隆组顶部燧石中发现微生物化石6属9种,其中丝状蓝菌1属4种Siphonophycus robustum,S.typicum,S.kestron,S.solidum;球状蓝菌3属3种Eoentophysalis belcherensis,Gloeodiniopsis lamellosa,Scissilisphaera bistratosa;分类位置未定2属2种Glenobotrydion majorinum,Globophycus rugosum。这些微体化石的发现为开展万隆组古环境分析及生物地层对比研究提供了新的素材。研究显示,万隆组燧石相微生物组合以发育管鞘藻席(Siphonophycus mat)为主要特征,丝状蓝菌呈横向展布,长可达400μm以上,显示原地或近原地埋藏的特点。生物群落古环境综合分析表明,吉林南部二道江地区万隆组顶部形成于潮下带或潮间带下部低能静水的沉积环境。The Tonian period marks one of the most critical time intervals in the evolutionary history of the early life and environment.It follows a golden age of cyanobacteria in the Mesoproterozoic and precedes a global biological collapse in the Cryogenian.The southern Jilin Province,situated on the northeastern margin of the North China block,offers an excellent opportunity to study paleontology,biostratigraphy and paleoenvironment during the Tonian period.This region boasts complete sedimentary successions of strata,well-exposed outcrops,and the presence of various well-preserved microfossils within chert bands,nodules,and shales.In this study,we present an assemblage of microfossils discovered in cherts from the uppermost sediments of the Wanlong Formation in the Erdaojiang area of south Jilin Province.We have identified a total of nine species belonging to six genera,including filamentous cyanobacteria such as Siphonophycus robustum,S.typicum,S.kestron,S.solidum,spheroidal cyanobacteria such as Eoentophysalis belcherensis,Gloeodiniopsis lamellosa,Scissilisphaera bistratosa and incertae sedis species like Glenobotrydion majorinum,Globophycus rugosum.These newly documented microfossils provide valuable insights into the paleoenvironment of the Wanlong Formation and facilitate the regional correlations of biostratigraphy.Furthermore,the microbiota is predominantly composed of cyanobacteria filaments,particularly Siphonophycus mat,with horizontally oriented filaments typically exceeding 400μm in length,indicating taphonomic characteristics of autochthonous or near-autochthonous preservation.The comprehensive analysis of the paleoenvironment suggests that the uppermost sediments of the Wanlong Formation in the Erdaojiang area of south Jilin Province represent a shallow,low intertidal or subtidal environment with a low sedimentation rate.

关 键 词：吉南地区 新元古代 拉伸纪 万隆组 微体化石 

分 类 号：P534.3[天文地球—古生物学与地层学] P532[天文地球—地质学] Q911.2[生物学—古生物学]