贵州瓮安震旦纪陡山沱期磷酸盐化球状化石的新观察

New Observations on Phosphatized Spheroidal Fossils in Sinian Doushantuoan Phosphorites in Weng'an, Guizhou Province

我国贵州瓮安陡山沱期磷块岩中的磷酸盐化球状化石是近年来受到广泛关注的一类微体化石。对于它们的生物亲缘认识,长期以来存在着动植物之争。特别是近年来一些学者发现,部分磷酸盐化球状化石内部保存了2、4、8、16等几何级数增长的细胞特征,根据化石的大小、细胞排列方式和表面纹饰可与现生甲壳类动物的胚胎比较,认为它们很可能是动物胚胎化石。但另一些学者却持截然不同的观点,认为它们不是动物胚胎化石而是绿藻门团藻类。本文主要依据最近通过醋酸浸解法在贵州瓮安震旦纪陡山沱期含磷地层发现的大量球状实体化石的观察与研究,同时结合相同层位岩石薄片所发现的大量同类化石微细结构的对比。特别是把磷块岩中的化石与燧石中发现的化石详细比较,对一些磷酸盐化球状化石的归属和亲缘关系进行探讨。研究表明贵州瓮安陡山沱期磷酸盐化微体化石群具有多样性特征,包含不同门类,是迄今为止全球保存最好的晚新元古代磷酸盐化的化石库。

In recent years much attention has been paid to phosphatized spheroidal fossils found in the Sinian Doushantuoan phosphorites in Weng'an, Guizhou Province. Disputes have been long existed about their phylo-genetic affinity. Based on some new discoveries and the present knowledge, some researchers interpret some of the phosphatized spheroidal fossils as animal embryos, whereas others hold the utterly different view that they are volvocacean green algae rather than animal embryos. In this paper, based on new data of the phosphatized spheroidal fossils found in the Sinian Doushantuoan phosphorites bed in Weng'an, Guizhou, combined with similar fossils found in thin sections, the affinity of some spheroidal fossils is discussed and reinterpreted. It is obvious that the phosphatized spheroidal fossil assemblage found in Weng'an consists of cyanobacteria, benthic mul-ticellular algae, planktonic acritarchs and other fossils with uncertain assignments, and provide an exceptionally well-preserved phosphatized Lagerstatten.