鄂西早三叠世南漳-远安动物群地层分布特征  

Strata Characteristics of the Early Triassic Nanzhang⁃Yuan’anFauna in Western Hubei Province

作　　者：阎春波[1,2,3] 李姜丽 程龙 赵璧[2,4] 邹亚锐 牛东毅 陈刚 方子晨 Yan Chunbo;Li Jiangli;Cheng Long;Zhao Bi;Zou Yarui;Niu Dongyi;Chen Gang;Fang Zicheng(Wuhan Center of China Geological Survey,Wuhan 430205,China;Geological Science and Technology Innovation Center of Central South China,Wuhan 430205,China;Key Laboratory for Paleontology and Coevolution of Life and Environment,China Geological Survey,Wuhan 430205,China;Hubei Institute of Geosciences,Wuhan 430034,China;School of Earth Sciences,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中国地质调查局武汉地质调查中心,湖北武汉430205 [2]中南地质科技创新中心,湖北武汉430205 [3]中国地质调查局古生物与生命-环境协同演化重点实验室,湖北武汉430205 [4]湖北省地质科学研究院,湖北武汉430034 [5]中国地质大学地球科学学院,湖北武汉430074

出　　处：《地球科学》2021年第1期122-135,共14页Earth Science

基　　金：国家自然科学基金项目(Nos.41402005,41972014);中国地质调查局地质调查项目(Nos.DD20160316,DD20190009);湖北省地质勘查基金项目(No.DTCG⁃190401);湖北省地质局科技项目(No.KJ2019⁃01).

摘　　要：在区域地质调查的基础上,以远安张家湾嘉陵江组剖面为重点,通过对南漳和远安交界地区下三叠统嘉陵江组剖面测制和多处化石点考察,重新厘定研究区内嘉陵江组岩性特征.认为研究区内的嘉陵江组划分为3个岩性段更为合理,产南漳−远安动物群的纹层状灰岩段位于二段顶部.通过系统化石发掘和张家湾剖面详细描述,初步查明了南漳−远安动物群的垂向分布特征:在30余米厚的纹层状灰岩段中均有海生爬行动物产出,只是丰度和分异度存在一定差异,其中7组岩层相对富集,顶部最为丰富.在此基础上,通过地层对比和所有化石点综合分析,将动物群自北东向南西划分为A~D 4个区带,依次命名为绝缘区、边缘区、相对富集区和富集区,分别对应化石从无到有、丰度逐渐变化及水深逐渐加深的过程,总体上仍处于水体循环受限的台内洼地或潟湖相环境.此次查明动物群的分布特征将为研究动物群生物与环境协同演化及其对早三叠世生物复苏的响应奠定良好的基础.Based on the study of fossils spots and representative sections of the Nanzhang⁃Yuan’an Fauna,especially the Zhangjiawan section in Yuan’an county,the lithostratigraphic characteristics of the Jialingjiang Formation was redefined between Nanzhang and Yuan’an areas.It is reasonable that the Jialingjiang Formation in those areas should be divided into three members,in which the Nanzhang-Yuan’an Fauna is mainly yielded in the upper part of Member II.The lithology yielded the Nanzhang⁃Yuan’an Fauna mainly consists of laminated micritic limestone intercalated with normal micrite.Through systematical fossil excavations and detailed descriptions of the Zhangjiawan section,the vertical stratigraphic distributions of the Nanzhang⁃Yuan’an Fauna are preliminary recognized.Marine reptile fossils could exist in almost whole strata of the upper part of Member II of the Jialingjiang Formation,but the fossil abundance and diversity change largely in different layers.The abundance and diversity are relatively higher in seven strata assemblages than others,the peak appeared at the uppermost assemblages.The horizontal paleogeographic distribution features of the fauna in those areas could be summarized as four facies belts,named A,B,C and D zones,which correspond to empty zone,marginal zone,relative enrichment zone and enrichment zone,respectively.Different zones reflect the fauna experienced from rare to rich,meanwhile the water depth gradually deepens from northeast to southwest.The distributions of the Nanzhang⁃Yuan’an Fauna indicate that the marine reptiles could live in restricted shallow water or lagoon environment.The research will lay a good foundation not only for the co⁃evolution between early marine reptiles and environment,but also for its response to the Early Triassic biological recovery.

关 键 词：南漳-远安动物群 海生爬行动物 嘉陵江组 张家湾剖面 早三叠世 鄂西 古生物 

分 类 号：P539[天文地球—古生物学与地层学]