湖北长阳古城埃迪卡拉系陡山沱组下部的疑源类化石组合

AN ACRITARCH ASSEMBLAGE FROM THE LOWER EDIACARAN DOUSHANTUO FORMATION IN CHANGYANG, HUBEI PROVINCE

本文系统报道长阳地区陡山沱组底部硅质结核中发现的疑源类微体化石,并在陡山沱组二段中首次发现Hocosphaeridium scaberfacium。研究发现,长阳古城剖面埃迪卡拉系陡山沱组底界之上13.9—22.6 m处产丰富的疑源类化石,目前已发现大型具刺疑源类化石9属11种(含1个未定种),包括:Distosphaera speciosa、Eotylotopalla dactylos、Ericiasphaera magna、Hocosphaeridium scaberfacium、Hocosphaeridium sp.、Mengeosphaera lunula、Appendisphaera grandis、Tanarium paucispinosum、Tianzhushania spinosa、Weissiella grandistella、Yinitianzhushania tuberifera。这一疑源类化石组合可与三峡地区建立的Appendisphaera grandis-Weissiella grandistella-Tianzhushania spinosa组合带进行对比。此外,在陡山沱组底部发现此前原认为属于陡山沱组上部的Hocosphaeridium scaberfacium,暗示陡山沱组大型具刺疑源类一些属种具有较长的地质延限。

This paper reports acritarchs in the chert nodules at the lower part of the Ediacaran Doushantuo Formation in Changyang area, among them Hocosphaeridium scaberfacium was discovered for the first time in the Member II of the Doushantuo Formation. The data show that there are abundant acritarch fossils in the interval of 13.9-22.6 m above the base of the Doushantuo Formation in Gucheng section, Changyang, including 9 genera and 11 species(including 1 undecided species) of large acanthomorphic acritarchs, namely Distosphaera speciosa, Eotylotopalla dactylos, Ericiasphaera magna, Hocosphaeridium scaberfacium, Hocosphaeridium sp., Mengeosphaera lunula, Appendisphaera grandis, Tanarium paucispinosum, Tianzhushania spinosa, Weissiella grandistella, Yinitianzhushania tuberifera. The acritarch assemblage in the Gucheng section can be compared with the Appendisphaera grandis-Weissiella grandistella-Tianzhushania spinosa Assemblage Zone established in the Yangtze Gorges area. In addition, the Hocosphaeridium scaberfacium, previously was only reported from the upper of the Doushantuo Formation, was discovered at the lower of the Doushantuo Formation, suggesting that some acritarchs of the Doushantuo Formation have long stratigraphic range.