浙江桐庐县刘家奥陶纪剖面生物地层学初步研究  

PRELIMINARY REPORT ON THE ORDOVICIAN BIOSTRATIGAPHY OF THE LIUJIA SECTION,TONGLU,ZHEJIANG PROVINCE

作　　者：张元动[1] 张举[1] 汪建国 宋妍妍[1] 汪隆武 俞国华 黎康清 

机构地区：[1]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,江苏南京210008 [2]浙江省地质调查研究院,浙江杭州311200

出　　处：《地层学杂志》2012年第1期1-12,共12页Journal of Stratigraphy

基　　金：自然科学基金(No.41172034);国家科技重大专项任务(2011ZX05008-001)支持

摘　　要：新发现的浙江桐庐刘家剖面位于马金—乌镇断裂与球川—萧山断裂之间,是浙西北地区以碎屑岩沉积为主的代表性奥陶纪地层剖面。根据所获得的宁国组和胡乐组的笔石化石,初步建立了该层段的笔石生物地层序列,自下而上包括Tetragraptus approximatus带、Corymbograptus deflexus带、Azygograptus suecicus带、Ex-igraptus clavus带、Undulograptus austrodentatus带、Acrograptus ellesae带、Dicellograptus vagus带、Nemagrap-tus gracilis带。在宁国组底部灰岩中发现少量牙形刺,指示时代为特马豆克期末到弗洛期初,与根据笔石化石得出的结论一致。在宁国组下部(下奥陶统弗洛阶上部)发现海绵化石,这在我国同期地层中尚属首次,具有重要的古生态学、生物古地理学和演化古生物学意义。在胡乐组上部识别出Dicellograptus vagus带,代表达瑞威尔阶顶部的地层,可与新疆大湾沟、北欧奥斯陆等地的相当地层对比。The Liujia section in Tonglu County, discovered in recent years, is located between the MajinWuzhen and Qiuchuan-Xiaoshan fault zones, and is one of the few Ordovician representative sections in Northwest Zhejiang. The section includes in ascending order the Yinchufu, Ningkuo, Hulo, Yenwashan, Huangnekang and Changwu formations, and is dominated by fine siliciclastics deposits. Based on the grap- tolites assemblage from the Ningkuo and Hulo formations, eight graptolite zones are preliminarily recog- nized, these are, in ascending order, the Tetragraptus approximates Zone, Corymbograptus deflexus Zone, Azygograptus suecicus Zone, Exigraptus clavus Zone, Undulograptus austrodentatus Zone, Acro- graptus ellesae Zone, Dicellograptus vagus Zone and Nemagraptus gracilis Zone. A few conodont species were also discovered from a basal limestone lens of the Ningkuo Formation, and they indicate an age of lat- est Tremadocian to earliest Floian, consisitent with graptolite biostratigraphy. Some large sponges were found in the lower part （dark gray shale, upper Floian） of the Ningkuo Formation. These are the first known sponge fissils from equivalent strata in China, and they offer new insights into the palaeoecology, palaeobiogeography, and evolutionary palaeobiology of the Ningkuo Formation. The Dicellograptus vagus Zone was provisionally adopted to refer to the topmost Darriwilian interval based on the occurrences of the eponymous species, and can be correlated with its equivalents in northwestern Tarim and Oslo region of Scandinavia.

关 键 词：生物地层 笔石 宁国组 奥陶系 桐庐 浙江 

分 类 号：P534.42[天文地球—古生物学与地层学]