【作者】 田树刚；

【Author】 Tian Shugang (Institute of Geologyy CAGS)

【机构】 中国地质科学院地质研究所；

【摘要】 本文主要从生物地层学角度探讨湘西北地区二叠-三叠系界线划分。笔者对该区上二叠世地层进行了重新划分,以牙形石地层分布、百分比丰度和演化关系为基础,将该区二叠系栖霞阶顶部至三叠系格里斯巴赫阶划分为13个牙形石带,并与区内其它门类化石带和国内外同期牙形石带做了详细对比；界线层夹有多层海底火山喷发物成因的伊利石-蒙脱石粘土岩, 界线上见有“过渡层”或生物“混生层”。证明该区界线地层为连续沉积。据界线上下“二叠型”与。“三叠型”生物的盛衰和演替,以菊石 Hypophiceras 带或“过渡层”的底部为该区二叠-三叠系界线。更多还原

【Abstract】 Northwestern Hunan Province is one of the best areas for studying Permo-Triassic boundary.Ten thousand and more conodont specimens have been obtained from five sections which belong to two kind of facies in this area.Based on the study of the distribution and the evolutionary relation- ships,13 conodont zones have been recognized from the uppermost Qixiaian of the Lower Permian to the Griesbachian of the Lower Triassic.These zones are identical with the zones of ammonoids,brachiopods,bivalves and fusulinids in this area,and entirely correlatable with tile conodont zones of other areas in South China and other regions.The zones are listed as follows. 1—Neogondolella idahoensis-N,serrata A.Z.,2—N.postserrata-N.aserrala A.Z.,3—N.babcocki-N,wilcoxi A.Z.,4—N.liangshanensis-N,bitteri A.Z., 5—N.leveni A.Z.,6—N.orientalis A.Z.,7—N.subcarinala-N,wangi A.Z., 8—N.postwangi-N,changxingensis A.Z.,9—N.xiangxiensis-N,changxingensis A.Z.,10—Unnamed Zone,11—Hindeodus parvus Z.,12—Isarcicella isarcica Z., 13—Neogondolella carinata-N.planata A.Z.更多还原