贵州麻江羊跳寒武系九门冲组微体化石初探  

A PRELIMINARY STUDY OF MICROSCOPIC SKELETAL FOSSILS FROM THE CAMBRIAN JIUMENCHONG FORMATION IN SOUTHEASTERN GUIZHOU,CHINA

作　　者：何树兴 杨兴莲[1,2] 吴维义[3] 朱雅杰[1] 段晓林[1] 

机构地区：[1]贵州大学资源与环境工程学院,贵阳550025 [2]现代古生物学和地层学国家重点实验室,中国科学院南京地质古生物研究所,南京210008 [3]贵州理工学院教务处,贵阳550003

出　　处：《古生物学报》2016年第2期160-169,共10页Acta Palaeontologica Sinica

基　　金：国家自然科学基金(41362002;41330101);国家重点基础研究发展计划(2013CB835002);现代古生物学和地层学国家重点实验室(中国科学院南京地质古生物研究所)(153113)联合资助

摘　　要：贵州麻江羊跳剖面寒武系九门冲组发育一套富含有机质的灰岩,经室内醋酸浸泡处理后,发现有海绵动物骨针和腕足动物的微体骨骼化石。海绵动物骨针包括粗短三轴六射针和细长三轴六射针。腕足动物经对比研究后将其鉴定为Eohadrotreta zhenbaensis,外部特征和内部结构均与陕南和鄂西地区的E.zhenbaensis非常相似,具有贝体轮廓亚圆形或横卵形、壳体饰以明显的同心纹,腹壳内顶坑浅弱或不发育、顶突起微凸,背壳假铰合面明显、中间沟和中支板发育良好等特征。E.zhenbaensis主要见于中国扬子区陕南和鄂西的寒武纪第二世地层中,在黔东斜坡相区九门冲组中尚属首次报道。E.zhenbaensis在黔东寒武系九门冲组的发现,不仅丰富了该组的生物组成面貌,扩展其地理分布,而且可为扬子区和过渡区不同岩石地层单位之间的对比提供信息。麻江羊跳寒武系九门冲组微体化石远较鄂西和陕南等地水井沱组中微体化石的分异度低,可能与当时麻江地区水体较深有关,为研究不同相区生物群落结构的变化提供了资料。Sponge spicules and brachiopods studied herein were collected from limestones of the Jiumenchong Formation at the Yangtiao section,Majiang County,Guizhou Province.These fossils were extracted from limestones with 3% acetic acid,and examined under SEM after being coated with gold. Sponge spicules consist of orthohexactines,clinohexactines and stubby hexactines.Examination revealed that the brachiopods belong to Eohadrotreta zhenbaensis which is similar to those recovered from southern Shaanxi Province and western Hubei Province,with subcircular to transversely oval outline,finely ornamented with concentric growth lines,lacking well-defined apical pits,apical process with slight uplift, dorsal median buttress and median groove welldeveloped.In the past,E.zhenbaensis was mainly found in the Cambrian Stage 2of southern Shaanxi and western Hubei.E.zhenbaensis was first found in eastern Guizhou Province,and it not only enriched the biological composition of the Jiumenchong Formation, but also provided information for comparing the lithostratigraphic units between the Yangtze Region and Transitional Region. The diversity and abundance of microscopic skeletal fossils in the Jiumenchong Formation at Majiang County are significantly fewer than those of the Shuijingtuo Formation in southern Shaanxi and western Hubei.It may indicate that compositions of fossil assemblages are controlled by water depth,and this could provide information of the change of the community structure in different facies.

关 键 词：海绵骨针 腕足动物 九门冲组 寒武系 贵州 

分 类 号：Q915.2[天文地球—古生物学与地层学]