华南板块上扬子陆表海志留系远岸区韩家店组的生物沉积特征  

BIOACCUMULATIONS OF THE SILURIAN HANCHIATIEN FORMATION IN THE OFF-SHOAL REGION OF THE UPPER YANGTZE EPICONTINENTAL SEA,SOUTH CHINA BLOCK

作　　者：邓小杰 李启剑 史振华 胡歆睿 蒋良兵 陈明华 冉维宇 李越[2] DENG Xiaojie;LI Qijian;SHI Zhenhua;HU Xinrui;JIANG Liangbing;CHEN Minghua;RAN Weiyu;LI Yue(Guizhou Geological Survey,Guiyang 550081,China;State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]贵州省地质调查院,贵阳550081 [2]中国科学院南京地质古生物研究所现代古生物学和地层学国家重点实验室,中国科学院生物演化与环境卓越创新中心,南京210008

出　　处：《微体古生物学报》2023年第1期33-42,共10页Acta Micropalaeontologica Sinica

基　　金：中国科学院战略性先导科技专项(B类)资助项目(XDB26000000);中国科学院青年创新促进会项目(2019310);贵州省科技计划项目(黔科合支撑[2020]4Y033号;黔科合支撑[2021]一般463号)的支持。

摘　　要：上扬子区志留系兰多维列统特列奇阶下部韩家店组以杂色泥岩-粉砂岩、细砂岩为主,大化石含量偏少,局部层段发育碳酸盐岩薄层或透镜体。本文划分黔北道真巴渔剖面韩家店组生物沉积类型并确认环境指标。滇黔桂古陆以北远岸区韩家店组底栖生物类型与其赋存的岩相存在相关性,泥质粉砂岩层面上常见生物潜穴,腕足类Nucleospira被水动力搬运后密集堆积形成贝壳滩;原地生长保存的苔藓虫Fistulipora群落形成厚度约0.2 m的薄层生物层。薄层碳酸盐岩层微相序列显示底栖生物多样性组成,以细生屑颗粒占优势,化石类型包括床板珊瑚、皱壁珊瑚、苔藓虫、腕足类、三叶虫、介形类、海百合茎以及钙藻等,均为栖居于陆表海缓坡富氧海底的常见类型;出现少量极浅水灰泥坪、云坪和内碎屑颗粒滩环境。韩家店组生物沉积特征指示该区海底深度维持在最大浪基面之上,为基底稳定沉降与沉积补偿大致均衡的构造背景。在扬子上升后至早二叠世海进的漫长古陆阶段,韩家店组地层产状未受到强烈褶皱变形。Lower Telychian Hanchiatien formation(Llandovery,Silurian)in the upper Yangtze epicontinental sea of South China Block is dominantly composed of motley mudstone and siltstone intercalated with lens or thin-bedded carbonates with low abundance of macrofossils.Bayu section of the Daozhen county,northern Guizhou province is employed for bioaccumulation classification and palaeoenvironmental parameter dating of the Hanchiatien formation in present paper.Types of benthic biota are close relationship to their lithofacies in the off-shoal setting of the Dian-Qian-Gui Land.Burrows are commonly occurred from surfaces of muddy siltstones.Coquinas of the Nucleospira(brachiopod)were re-sedimented as concentration bed.Thin autobiostromes with thickness about 0.2 m were formed by the Fistulipora(bryozoan)community.Microfacies of the thin-bedded carbonates are illustrated for insight of biodiversity;they are rich in fine-grained bioclasts.Fossil taxa are identified as common elements in shallow and oxygenated ramp of an epicontinental sea;they are tabulate corals,rugose corals,bryozoa,brachiopods,trilobites,ostracods,crinoids and calcareous algae etc..Very shallow carbonate facies include limemud flat,dolomitic flat and intraclastic bank.Bioaccumulations throughout the Hanchiatien formation are notable indicators that the marine-floor herein maintained a depth above the major wave-base.Meanwhile,the basement of the basin was stable subsidence and equivalent to the sedimentary compensation rate tectonically.The Hanchiatien formation strata were not strongly folded onward long-term land episode from Yangtze uplift to the Early Permian transgression.

关 键 词：生物沉积 环境指标 远岸区 韩家店组 志留系 上扬子区 

分 类 号：Q911[天文地球—古生物学与地层学] P534.43[生物学—古生物学] P512.2