陕西宁强—四川广元地区奥陶系“涧草沟组”和宝塔组牙形刺生物地层研究之新进展  

ADVANCES OF THE CONODONT BIOSTRATIGRAPHY OF THE ORDOVICIAN“CHIENTSAOKOU”AND PAGODA FORMATIONS IN NINGQIANG,SHAANXI PROVINCE,AND GUANGYUAN,SICHUAN PROVINCE

作　　者：方翔[1] 张元动[1,3] 王志浩 甄勇毅[2] 周志强 张俊鹏[1] 张琳娜 FANG Xiang;ZHANG Yuandong;WANG Zhihao;ZHEN Yongyi;ZHOU Zhiqiang;ZHANG Junpeng;ZHANG Linna(State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008,China;Geological Survey of New South Wales,Londonderry NSW 2753,Australia;University of Chinese Academy of Sciences,Beijing 100049,China;Xi’an Center of Geological Survey,Xi'an 710054,China)

机构地区：[1]中国科学院南京地质古生物研究所和生物演化与环境卓越创新中心,现代古生物学和地层学国家重点实验室,南京210008 [2]Geological Survey of NewSouth Wales,Londonderry NSW 2753,Australia [3]中国科学院大学,北京100049 [4]中国地质调查局西安地质调查中心,西安710054

出　　处：《微体古生物学报》2020年第2期129-144,共16页Acta Micropalaeontologica Sinica

基　　金：中国科学院(XDB26000000);国家自然科学基金委(41772005);国家科技重大专项(2017ZX05036-001-004);地质调查项目(DD20190009)联合资助;IGCP653项目“奥陶纪生物大辐射的启动过程”的阶段成果。

摘　　要：开展陕西宁强范家沟、赵家坝和四川广元谭家沟3条剖面奥陶系牙形刺生物地层研究。在宁强地区"涧草沟组"发现了凯迪阶中部的Protopanderodus insculptus生物带,它相当于湖北宜昌地区上奥陶统临湘组之同名带;宝塔组由上而下可划分为Hamarodus brevirameus,Baltoniodus variabilis,Yangtzeplacognathus jianyeensis和Y.foliaceus等牙形刺带,属达瑞威尔阶上部至凯迪阶下部,可与湖北宜昌地区中-上奥陶统牯牛潭组顶部至宝塔组的同名带对比;广元地区宝塔组则见Baltoniodus variabilis和Yangtzeplacognathus jianyeensis生物带,属达瑞威尔阶顶部至桑比阶,可与湖北宜昌地区庙坡组或南京地区大田坝组的同名带对比。上述发现改变了先前的认识:陕西宁强地区宝塔组划分为Hamarodus europaeus和Eoplacognathus jianyeensis两牙形刺带,与湖北宜昌地区庙坡组和宝塔组地层相当;四川广元地区宝塔组归入Pygodus serra-Eoplacognathus foliaceus牙形刺带,与湖北宜昌地区牯牛潭组对比。邱洪荣(1989)建立的4个新种可能是一些老属种不同形态的组成分子,因此在本文属种描述部分把它们分别列入相应属种的同义名录。Conodonts of the Pagoda Formation in Ningqiang,southern Shaanxi Province,were previously referred to the Hamarodus europaeus(=H.Brevirameus)and Eoplacognathus(=Yangtzeplacognathus)jianyeensis biozones,which were correlated to those of the Pagoda and Miaopo formations in Yichang,Hubei Province.However,conodonts of the Pagoda Formation in Guangyuan,northern Sichuan Province,were assigned to the Eoplacognathus fo-liaceus-Pygodus serra Biozone of the upper Darriwilian,correlating with the Kuniutan Formation of the Yichang area,Hubei Province.We report herein the new biostratigraphic data based on the study of the conodonts from the Pagoda and‘Chientsaokou’formations at the Zhaojiaba and Hujiaba sections of Ningqiang,southern Shaanxi Province,and at the Tanjiagou section of Guangyuan,Sichuan Province.Our new findings include:(1)the conodont fauna from the"Chientsaokou"Formation is assignable to the middle Katian Protopanderodus insculptus Biozone,which is also re-cognized in the Linhsiang Formation exposed in the Yichang area,Hubei Province,and in the Jiangning area,Nanjing,Jiangsu Province;(2)four conodont biozones,including(in descending order)the Hamarodus brevirameus,Baltoniodus variabilis,Yangtzeplacognathus jianyeensis and Y.protramosus biozones,have been recognized in the Pagoda Formation in Ningqiang,confirming a latest Darriwilian to early Katian age for the formation that can be correlated with the stratigraphical interval from the top of the Kuniutan Formation to the top of the Pagoda Formation,rather than with the Miaopo and Pagoda formations in the Yichang and Nanjing areas;and(3)the Pagoda Formation at the Tanjiagou section of Guangyuan,Sichuan,consists of only the Baltoniodus variabilis and Yangtzeplacognathus jianyeensis biozones,extending the uppermost Darriwilian and Sandbian,and thus is correlated with the Miaopo or Datianba formations,rather than with the Kuniutan Formation in the Yichang and Nanjing areas.

关 键 词：牙形刺生物地层 “涧草沟组” 宝塔组 奥陶系 陕西宁强 四川广元 

分 类 号：Q915[天文地球—古生物学与地层学]