陕南勉县寒武系第三阶仙女洞组古杯动物化石及其生物地层意义  

ARCHAEOCYATH FOSSILS FROM THE CAMBRIAN STAGE 3 XIANNÜDONG FORMATION IN THE MIANXIAN,SOUTH SHAANXI AND THEIR BIOSTRATIGRAPHIC SIGNIFICANCE

作　　者：朱杨格 刘丽静 贾连奇 沈锦文 甘德祥 ZHU Yang Ge;LIU Li Jing;JIA Lian Qi;SHEN Jin Wen;GAN De Xiang(State Key Laboratory of Continental Dynamics,Shaanxi Key Laboratory of Early Life and Environments,and Department of Geology,Northwest University,Xi’an 710069)

机构地区：[1]西北大学地质学系,大陆动力学国家重点实验室,早期生命与环境陕西省重点实验室,陕西西安710069

出　　处：《地层学杂志》2024年第3期237-252,共16页Journal of Stratigraphy

基　　金：国家自然科学基金(42072127、41930319、41972143、42272006);国家重点研发计划(2023YFF0803600)共同资助。

摘　　要：古杯动物是寒武系第二阶至第四阶生物地层划分和对比的重要化石。前人已在福成、新潮、十里溪、岩孔及王家坪剖面的地层中建立了5个古杯动物化石带(层),但是扬子地台其他地区古杯动物化石带仍未建立,各地区之间的古杯生物地层对比存在困难。笔者在陕西勉县发现了一个新的产古杯动物化石的寒武系剖面——黑滩沟剖面,对郭家坝组顶部钙质结核和仙女洞组非礁相灰岩中的古杯动物化石进行了详细研究,共鉴定出7属7种和2个未定属种,包括1个新属新种Shaanxicyathus spinosus gen.et sp.nov.。黑滩沟剖面仙女洞组的中下部地层中可识别出2个古杯动物化石带,自下至上为:Dailycyathus dubius带和Shaanxicyathus spinosus-Archaeopharetra tabulates组合带。Dailycyathus dubius带与扬子地台第一个古杯动物化石带(福成剖面仙女洞组的Dailycyathus xiuqiensis带)相当,Shaanxicyathus spinosus-Archaeopharetra tabulates组合带与其第二个古杯动物化石带(福成剖面仙女洞组的Dictyocyathus shaanxiensis带)相当。黑滩沟剖面与福成剖面第一个古杯动物化石带的底界均为仙女洞组的底界,因此黑滩沟剖面与福成剖面的仙女洞组底界相当。黑滩沟剖面古杯动物化石带的建立为扬子地台不同地区仙女洞组的地层对比提供了新依据。The archaeocyaths are important for the biostratigraphic divisions and correlations of the Cambrian Stage 2 to Stage 4.Previously,five archaeocyath zones(beds)have been defined in Fucheng,Xinchao,Yankong,Shilixi,and Wangjiaping sections.However,the archaeocyath zones in other areas of the Yangtze Platform have not yet been established,which makes it difficult for the stratigraphic correlations.In Mianxian,South Shaanxi,we discovered a new Cambrian section containing the archaeocyaths—the Heitan’gou section,and studied in detail the archaeocyath fossils from calcareous nodules of the top of the Guojiaba Formation and non-reef limestone of the Xiannüdong Formation.Seven genera,seven species,and two unidentified genera(species)were identified in the Heitan’gou section,including a new genus and a new species:Shaanxicyathus spinosus gen.et sp.nov.Two archaeocyath zones can be recognized from the bottom to the middle of the Xiannüdong Formation of the Heitan’gou section,from bottom to top:Dailycyathus dubius zone and Shaanxicyathus spinosus-Archaeopharetra tabulates assemblage zone.The Dailycyathus dubius zone can be correlated with the first archaeocyath zone of the Yangtze Platform(Dailycyathus xiuqiensis Zone of the Xiannvdong Formation in the Fucheng section),and the Shaanxicyathus spinosus-Archaeopharetra tabulates assemblage zone correlates with its second archaeocyath zone(Dictyocyathus shaanxiensis zone of the Xiannvdong Formation in the Fucheng section).The bottom boundary of the first archaeocyath zone in both the Heitan’gou section and the Fucheng section is the bottom boundary of the Xiannvdong Formation,so the bottom boundary of the Xiannüdong Formation in the Heitan’gou section correlates to that in the Fucheng section.The establishment of archaeocyath zones in the Heitan’gou section provides a new basis for stratigraphic correlations of the Xiannüdong Formation in different areas of the Yangtze Platform.

关 键 词：古杯动物 第二统 仙女洞组 扬子地台 汉南—米仓山地区 生物地层 

分 类 号：P534.41[天文地球—古生物学与地层学]