中文摘要：

中国天津蓟县古元古代长城系串岭沟组页岩中保存有丰富的球形疑源类化石。本文对这一微化石组合进行了光学生物显微镜、扫描电子显微镜和透射电子显微镜的对比研究。研究发现,以往一些被作为属征的结构,如,膜壳壁的厚薄、网状纹饰和褶皱等,很可能是生物降解和成岩作用的结果。因此,以前描述的10个不同属的球形疑源类的系统分类有待于重新研究和厘定,也许把它们都归入光面球藻属Leiosphaeridia更合适。在透射电子显微镜下观察,球形疑源类壁的超微结构一致,都分为三层,中间层为电子密度低的较厚层,内层和外层为电子密度高的较薄层。这一特征与现生绿藻非常类似而与蓝藻包鞘明显不同,表明串岭沟组的球形疑源类可能与绿藻有较近的亲缘关系。

英文摘要：

A spheroidal acritarch assemblage was well preserved in the Paleoproterozoic Chuanlinggou Formation, Changcheng System at Jixian, Tianjin, northern China. Ten generic names have been applied by various authors to spheroidal acritarchs from the Chuanlinggou shales, but in an examination of jointly using optical microscopy, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, the suggested diagnostic characters, such as wall thickness, irregular folds and reticular structures on the vesicle surface could be formed in the processes of biological decay and diagenesis. Therefore, the taxonomy of the Chuanlinggou spheroidal acritarchs should be restudied in the future; the 10 documented genera would be referred to Leiosphaeridia. Furthermore, TEM reveals that the wall of the spheroidal acritarchs display a typical trilaminar structure in which a thick inner electron-tenuous layer （0.1 to 0.3 μm） is sandwiched between two thin （1-2 nm） electron-dense surface layers. This sort of ultra-structure is also unique to eukaryotes as seen among many extant chlorococcalean green algae （e. g. Chlorella zofingiensis） and is different from the structure of cyanobacterial sheath. The Chuanlinggou spheroidal acritarchs are probably green algae in affinity.