关于峡东陡山沱组具刺疑源类化石研究的补充

An Additional Study on Spinose Acritarches from the Doushantuo Formation in the Eastern Yangtze Gorges

在峡东陡山沱组黑色燧石中前人报道了多种多样的具刺疑源类化石,笔者最近重新研究了陡山沱组岩石切片中的具刺疑源类,发现微化石三维地保存在几乎没蚀变的条件下。这个生物群落包括Filisphaeridi-um,Baltisphaeridium,Comasphaeridium和Tianzhushania等分子。它们中的Tianzhushania在外表及形态上可与产自挪威斯瓦尔巴德群岛晚里菲岩层中的Trachyhystrichosphaera aimika比较。Trachyhystrichosphaera aimika是晚前寒武纪最特殊和分布最广的一个分子,目前已知至少产自世界上15个地区的晚里菲岩层中,对于新元古代前文德地层似乎是一个出色的指示化石。产自陡山沱组的Tianzhushania似乎支持Butterfield的观点,即:陡山沱组硅化碳酸盐沉积的年代早于伊迪卡拉后生动物多样化的时期。但是,由于化石只发现于少数岩石薄片中,因此,这些化石或许只代表峡东陡山沱组局部的生态环境。文中还讨论了陡山沱组的沉积环境及化石的保存。

The diversed spinose acritarchs have been reported in the Doushantuo black chers from eastern Yangtze Gorges. Recently, writer has restudied the spinose acritarchs in thin sections of the Doushantuo Formation. The microfossils are three-dimensionally preserved in a structurally little altered condition. The assemblage includes Filis phaeridium, Baltisphaeridium, Comasphaeridium and Tianzhushania. Among the taxa, Tianzhushania is comparable in appearance and shape to Trachyhystrkhosphaera aimika from the Svanbergfjellet Formation in northeastern Spitsbergen. Trachyhystrichosphaera aimika is one of the most distinctive and widely distributed of the late Proterozoic acritarchs, now known from at least 15 localities worldwide, it occurs in rocks of Late Riphean age and appears to be an excellent index fossil for the pre-Vendian Neoproterozoic. Tianzhushania from the Doushantuo Formation appears to support the about-mentioned Butterfield' position. That is, it seems that the sediments of the Doushantuo Formation are older than the diverse Ediacaran assemblage.Owing to the fossils are only found from a handful of the thin sections, these microfossils may be represent the parts of the ecological environment from the Doushantuo Formation in eastern Yangtze Gorges. The sedimentary environment and the fossil preservation of the Doushantuo Formation is discussed in this paper.