右江盆地西北缘安然背斜东段奥伦尼克期牙形石生物地层研究及地质意义  

The conodont biostratigraphic study and its geological significancein the Olenekian stage,east of the Anran anticline,northwest margin of the Youjiang basin

作　　者：向坤鹏 安亚运 贺永忠 赵磊 刘奎勇 盘应娟 易成兴 XIANG Kunpeng;AN Yayun;HE Yongzhong;ZHAO Lei;LIU Kuiyong;PAN Yingjuan;YI Chengxing(Guizhou Geological Survey,Guiyang,Guizhou 550081,China)

机构地区：[1]贵州省地质调查院,贵州贵阳550081

出　　处：《地质学报》2021年第8期2333-2345,共13页Acta Geologica Sinica

基　　金：中国地质调查局项目(编号DD20160020);贵州省地质矿产勘查开发局科研项目(编号QDKKH[2020]29);贵州省科学技术厅项目(编号QKHPTRC[2018]5626)联合资助的成果。

摘　　要：罗楼组上部灰岩段是右江盆地西北缘奥伦尼克期海生爬行动物化石的唯一赋存层位,生物地层研究精度较低。本文以安然背斜东段敢南、者堡一带罗楼组为研究对象,通过剖面测制,对该组上部灰岩段进行系统的牙形石生物地层研究。结果显示,敢南一带罗楼组上部可识别出5个牙形石带,者堡一带罗楼组上部可识别出3个牙形石带。根据两条剖面牙形石生物地层对比,认为右江盆地西北缘奥伦尼克期包含5个牙形石带,自下而上依次为:Neospathodus pakistanensis带、Novispathodus waageni带、Neospathodus crassatus带、Icriospathodus collinsoni带以及Triassospathodus homeri-Tr.symmetricus组合带。区内早三叠世海生爬行动物主要产于Triassospathodus homeri-Tr.symmetricus组合带。该研究结果为罗楼组上部灰岩段海生爬行动物群时代的限定提供可靠的生物依据,并为进行奥伦尼克期海生爬行动物群产出层位的精细对比提供佐证。Limited biostratigraphic studies have been undertaken on the upper limestone member of the Luolou Formation which is also the only occurrence horizon of the marine reptile in the Olenekian Stage,northwest margin of the Youjiang basin.This article focused on the upper limestone member of the Luolou Formation in the Zhebao and Gannan regions,respectively,east of the Anran anticline.Based on the section and systematic conodont biostratigraphic study,the results show 5 and 3 conodont zones can be identified in the upper limestone member of the Luolou Formation in the Gannan and Zhebao regions,respectively.According to the conodont biostratigraphic correlation of two sections,5 conodont zones were established in the northwestern margin of the Youjiang basin,Olenekian Stage,and from the bottom upwards as follows:the Neospathodus pakistanensis zone,the Novispathodus waageni zone,the Neospathodus crassatus zone,the Icriospathodus collinsoni zone and the Triassospathodus homeri-Tr.symmetricus assemblage zone.The Early Triassic marine reptiles in northwest margin of the Youjiang basin mainly belong to the Triassospathodus homeri-Tr.symmetricus assemblage zone.The results of this study not only provide reliable biological basis for age limit of the reptile fauna in the upper limestone member of the Luolou Formation,but also provide evidence for careful comparison of occurrence horizon of the marine reptile fauna,Olenekian Stage.

关 键 词：罗楼组 奥伦尼克期 牙形石生物地层 安然背斜东段 右江盆地西北缘 

分 类 号：Q915.2[天文地球—古生物学与地层学]