【摘要】 <正> 过去一般都认为以页岩为主的龙马溪组属早志留世与兰多维列期相当;罗惹坪组(或石牛栏组)以灰岩为主,代表中志留世与温洛克期对比;纱帽组以砂岩、页岩为主,属晚志留世,相当于罗德洛期。根据近年来的研究,认为本区无晚志留世的沉积,中志留世的地层也发育不全;而且岩相变化很大,以碳酸盐岩的出现就作为中志留世沉积的开始,这种划分方法是不合适的。本区介壳相沉积与笔石相沉积,在横向上是互相变换互为消长的。标准地点的罗惹坪组和石牛栏组的全部以及纱帽组,韩家店组的大部均为早志留世的沉积。本区的分层系统自下而上:下志留统为龙马溪组、香树园组、雷家屯组、马脚冲组、溶溪组;中志留统为秀山组、回星哨组。更多还原

【Abstract】 The present study is based on the stroma-toporoids collected from the Lower Silurianin northeastern Guizhou and southwesternHubei.The Lower Silurian exposed in nor-theastern Guizhou may be divided ascendinglyinto 5 formations:Lungmachi,Xiangshuyuan,Leijiatun,Majiachong and Rongxi.Thestromatoporoids mainly occur in the Xiang-shuyuan and Leijiatun formations.The Xiang-shuyuan formation is characterized by Clathro-dictyon,Intexodictyon and Plexodictyon;whilethe Leijiatun formation by Forolinia,Rosenella,Ludictyon,Labechia,Pseudolabechia and Cla-vidictyon.Generally the stromatoporoids,mostdeveloped in the Leijiatun formation,bearsimilarities to those of the Xiangshuyuanformation on the one hand,and show strikingdifference from them on the other hand.Furthermore,by comparison the Early Silurianstromatoporoids in the above two formationsbear a closer affinity to those in Estonia ratherthan those in other parts of the world.Insouthwestern Hubei the stromatoporoids werefound in the Lojoping formation.The mainrepresentatives are:Intexodictyon,Clathrodic-tyon and Labechia.Through the study ofstromatoporoids and other fossils,it is believedthat the Lojoping formation may be correlatedwith the Xiangshuyuan formation,the lowerand middle parts of Leijiatun formation,belonging to the middle and late LowerSilurian,or corresponding to the Middle andLate Llandoverian stage.In this paper 16 species of EarlySilurian stromatoporoids are described.They are:Labechia sibirica Yavorsky,Clathrodictyon simplex(Nestor),C.incon-grum Birkhead,C.circulatum Yang et Dong (sp.nov.),C.sulevi Nestor,C.mammillatum(F.schmidt),C.striatellum(D’Orbigny),C.longum Yang et Dong(sp.nov.),C.dazhong-baense Yang et Dong(sp.nov.),Ecclimadic-tyon hoigiense Nestor,Intexodictyon yichan-gense Yang et Dong(sp.nov.),Clavidictyonhubeiense Yang et Dong(sp.nov.),C.guiz-houense Yang et Dong(sp.nov.),Plexodict-yon inequale Yang et Dong(sp.nov.),P.grossum Yang et Dong(sp.nov.)and P.sina-nense Yang et Dong(sp.nov.).Among themthe first 12 species were collected from south-western Hubei and the last 4 from north-eastern Guizhou.更多还原