广西凌云县罗楼地区早三叠世牙形石

罗楼地区下三叠统，经赵金科（１９５９）研究显示，最低层位为Ｖishnuites marginalis菊石带（Gyronitan阶），张舜新（１９９０）研究广西凤山金下三叠统形石时，未发现最高的牙形石带，当前研究发现，罗楼地区下三叠统牙形石丰富，可识别出Ｈindeodus parvus,Isarciclla staeschei ,Neospathodus waageni,Neospathodus novaehel-landiae,Neospathodus homeri-Neospathodus triangularis,Chiosella timorensis6个牙形石带（组合带），从而表明该地区不但存在下三叠统底部层位Ｏtoceratan阶，而且存在下三叠统最高的牙形石带，牙形石组合面貌和岩相显示，该牙形石动物群生活环境与田东县作登地区同属盆地相环境。

EARLY TRIASSIC CONODONTS FROM LUOLOU FORMATION IN LUOLOU, LINGYUN, GUANGXI

The conodonts described in the present paper were collected from two Luolou sections, Luolou district, Lingyun County, Guangxi Zhuang' s Autonomous Region. Six conodont zones have been recognized, in ascending or der they are Hindeodus parvus Zone, Isarcicella staeschei Zone, Neospathodus waageni Zone, Neospathodus novae hellandiae Zone, Neospathodus homeri-Neospathodus tri angularis Assemblage Zone and Chiosella timorensis Zone. These conodont zones first demonstrate that not on ly the lowermost Lower Triassic strata but also the highest Lower Triassic strata are present in the Luolou district. By analysis of conodont fauna and the sedimentary rocks, the sediment environment of Early Triassic in Luolou dis trict may belong to lower energy, relatively deeper water and normal salinity (3.5%), that is, an opened basinal sea. This type of sediment environment has been found at Zoudeng, Tiandong, Guangxi and several other places in Southern Guizhou, Northern Guangxi. They were called the “Zoudeng Type” or “basinal facies type”.