湖南慈利高化剖面二叠系-三叠系界线地层微生物化石  

THE PERMIAN-TRIASSIC BOUNDARY MICROFOSSILS FROM THE GAOHUA SECTION,CILI COUNTY,HUNAN PROVINCE

作　　者：陈宗霞 华杰群 邢安娜 姜红霞 王青春 贺萍 王丽娜 CHEN Zongxia;HUA Jiequn;XING Anna;JIANG Hongxia;WANG Qingchun;HE Ping;WANG Lina(School of Earth Science,Hebei GEO University,Shijiazhuang 050031,China;Hebei Key Laboratory of Strategic Critical Mineral Resources,Hebei GEO University,Shijiazhuang 050031,China;Huaxin College of Hebei GEO University,Xinle of Shijiazhuang 050700,China)

机构地区：[1]河北地质大学地球科学学院,石家庄050031 [2]河北地质大学,河北省战略性关键矿产资源重点实验室,石家庄050031 [3]河北地质大学华信学院,石家庄新乐市050700

出　　处：《微体古生物学报》2023年第2期120-130,共11页Acta Micropalaeontologica Sinica

基　　金：国家自然科学基金青年基金(41802016);河北省自然科学基金青年基金(D2018403044);河北地质大学科研启动基金(BQ2017014)的支持。

摘　　要：二叠纪末期的生物大灭绝事件极大地重塑了地球上的生物面貌,古生代浅海中盛行的后生动物遭受到了重创,在早三叠世变得稀少,取而代之的是广泛分布的微生物岩。微生物岩代表着生物大灭绝后一种独特的生态环境,其形成及其中微生物的组成对研究生物大灭绝后生物的复苏机制具有重要的意义。在二叠纪-三叠纪(P/T)之交,中国华南地区位于古特提斯洋低纬地区,广泛发育多种微生物岩。本文选取湖南慈利高化剖面,聚焦P/T界线附近的地层,对上二叠统长兴组和下三叠统大冶组中的后生生物化石和微生物化石展开镜下观察。结果显示,长兴组顶部生物化石丰富,含介形类、藻类、苔藓虫、?类有孔虫和其他有孔虫等,其中有孔虫丰度较高。在大冶组底部生物面貌发生了大的变化,仅剩少量介形类和有孔虫,另发现牙形类和微型腹足类。此外,在高化剖面微生物岩中首次发现了球形微生物和Gakhumella型微生物化石。Coccoids型化石保存了更完整的轮廓,这些球状化石与现存的附生蓝藻Stanieria有关,本文中鉴定为Stanieria,而Gakhumella型化石外部轮廓基本消失,但仍清晰可见由内部层节堆叠而成的柱状外形。通过对比发现高化剖面中的微生物化石与华南其他地区同时代发育的微生物岩类似,但保存状态有所差别,这种差异应该是不同的矿化和保存条件造成的。The End-Permian Mass Extinction Event(EPME)is the largest extinction in the earth history.The metazoans in the shallow marine water were dramatically damaged and replaced by widely distributed microbialites during the Early Triassic.Detailed researches regarding the distribution and the formation of microbialites are important.Especially,studies focusing on the temporal and spatial distribution of microbials in the microbialites is crucial to understanding the mechanisms of biological recovery after the EPME.To better understand the nature of microbialites,47 thin sections from the Gaohua Permian-Triassic Boundary(P/TB)section from Cili County,Hunan Province,have been investigated in terms of the Metazoan and the microbial fossils.The P/TB strata from Gaohua are composed of the upper part of the Changxing Formation and the lower part of the Daye Formation.After carefully examining the thin sections,abundant fossil fragments of ostracods,algae,foraminifers and fusulinids have been found in the uppermost Changxing Formation.Only a few foraminifers and ostracods remained at the bottom of the Daye Formation,and microfossils of conodont and microgastropod also appeared.Surprisingly,microbial fossils of Stanieria and Gakhumella were first found in the microbialites at the Gaohua section.The Stanieria are characterised by a better-preserved outline,but the Gakhumella group are remineralised and replaced by calcite crystals.Although the microbes in this study do not differ significantly from those reported from other parts of South China,the discovery of Stanieria and Gakhumella enhances our understanding of the genesis of microbialites and the post-extinction marine ecosystem.

关 键 词：微生物岩 Stanieria Gakhumella 二叠纪-三叠纪界线 慈利 

分 类 号：Q911.2[天文地球—古生物学与地层学]