广西、云南的PSEUDOSCHWAGERINA化石及其地层意义

FOSSIL PSEUDOSCHWAGERINA (FUSULINID)FROM YISHAN, GUANGXI AND BABAO,YUNNAN

该文记述了广西宜山马脑山剖面及云南八宝小独山剖面Pseudoschwaserina属34种(亚种),分析了两剖面Pseudoschwagerina动物群的面貌,讨论了Pseudoschwagerina的地层意义。研究表明,两剖面Pseudoschwagerina动物群具有地方性种稀少的共同特点,大多数种皆为广相型分子。从动物群的组成上看,广西、云南Pseudoschwagerina动物群与我国贵州、北美及俄罗斯等地的Pseudoschwagerina动物群有较大的相似性。但是,目前归入 Pseudoschwagerina名下的各种在形态上有着较大的差异,造成不同地区合Pseudoschwagerina地层带化石难以直接对比。根据对两剖面Pseudoschwagerina地层分布规律的研究以及国内、外Pseudochwagerina地理分布的资料,笔者建议选用 Pseudoschwagerina uddeni,P.beedei,P.robusta等 Pseudoschwagerina的典型分子做为含Pseudoschwagerina地层划分、对比的首要标准类群,选用P.uddeni和P.robusta分别做为确定Pseudoschwagerina带底、顶界线的首要标准种,以便于含Pseudoschwagerina地层的全球性的对比。

This article analyzes the species composition of the Pseudoschwagerina fauna from Yi-shan, Guangxi and Babao, Yunnan, which includes 34 species and subspecies identified frommore than 1000 thin sections. The stratigraphic significance of this genus in determining theCarboniferous--Permian boundary is discussed. Study results show that most species and sub-species in the Pseudoschwagerina fauna have a wide geographic distribution and the majorspecies of this fauna are similar to those of North America and Russia. However, it has alsobeen found that the species currently assigned to Pseudoschwagerina have a wide range ofmorphological variation, which brings difficulties in the direct correlation of index species be-tween the Pseudoschwagerina zones in different regions. Based on the stratigraphical distribution of Pseudoschwagerina in Guangxi and Yunnanand on the geographical distribution of its different species, it is suggested that the typicalspecies of Pseudoschwagerina, such as P. uddeni, P. beedei and P. robusta, should be usedas the primary index species group in the global correlation of Pseudoschwagerina--bearingbeds to avoid the taxonomic problems of the pseudoschwagerinids, and that P. uddeni andP. robusta should be considered as the primary index species in defining the lower and upperboundaries of the Pseudoschwagerina zone respectively.