Basal Cambrian Microfossils from the Yangtze Gorges Area (South China) and the Aksu Area (Tarim Block, Northwestern China)
Basal Cambrian Microfossils from the Yangtze Gorges Area (South China) and the Aksu Area (Tarim Block, Northwestern China)
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DOI：
10.1017/s0022336000058108
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
Lin Dong;S. Xiao;B. Shen;Chuanming Zhou;Guoxiang Li;Jinxian Yao
中科院分区：
文献类型：
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作者：
Lin Dong;S. Xiao;B. Shen;Chuanming Zhou;Guoxiang Li;Jinxian Yao
基底寒武纪标志着生命史上一个重要篇章的开始。然而，大多数关于基底寒武纪的古生物学工作都集中在骨骼动物化石上，我们对主要生产者-蓝藻和真核浮游植物（例如，acritarchs） -的了解有限。本文研究了长江三峡地区延家河组和阿克苏地区玉都斯组磷质岩和燧石中保存的寒武纪基底尖喙生物、球藻微化石和蓝藻。我们的研究证实了这两个地层中存在具有基寒武纪Asteridium-Comasphaeridium-Heliosphaeridium （ACH）组合特征的小棘形螨。这些寄生生物包括丰富的Heliosphaeridium ampliatum (Wang, 1985) Yao et al., 2005，常见的Yurtusia uniformis n. gen.和n. sp.，以及罕见的Comasphaeridium annulare (Wang, 1985) Yao et al., 2005。此外，这些基底寒武纪演替还包含簇状球状微化石云南古ophycus yunnanensis (Song In Luo et al., 1982) n. comb。，几种丝状蓝藻[Cyanonema majus n. sp., Oscillatoriopsis longa Timofeev and Hermann, 1979，和Siphonophycus robustum (Schopf, 1968) Knoll et al., 1991]，以及表状管状微化石megthrix longus L. Yin, 1987a, n.修订。其中一些分类群（如：H. ampliatum、C. annulare和M. longus）具有广泛的地理分布，但只出现在基底寒武纪序列中，这支持了它们在生物地层学上的重要性。本文所报道的微化石地层产状与其他已发表的骨骼动物化石的对比表明，动物和浮游植物在寒武纪大爆发期间是串联辐射的。
Abstract The basal Cambrian marks the beginning of an important chapter in the history of life. However, most paleontological work on the basal Cambrian has been focused on skeletal animal fossils, and our knowledge about the primary producers—cyanobacteria and eukaryotic phytoplankton (e.g., acritarchs)—is limited. In this research, we have investigated basal Cambrian acritarchs, coccoidal microfossils, and cyanobacteria preserved in phosphorites and cherts of the Yanjiahe Formation in the Yangtze Gorges area (South China) and the Yurtus Formation in the Aksu area (Tarim Block, northwestern China). Our study confirms the occurrence in these two formations of small acanthomorphic acritarchs characteristic of the basal Cambrian Asteridium–Comasphaeridium–Heliosphaeridium (ACH) assemblage. These acritarchs include abundant Heliosphaeridium ampliatum (Wang, 1985) Yao et al., 2005, common Yurtusia uniformis n. gen. and n. sp., and rare Comasphaeridium annulare (Wang, 1985) Yao et al., 2005. In addition, these basal Cambrian successions also contain the clustered coccoidal microfossil Archaeophycus yunnanensis (Song in Luo et al., 1982) n. comb., several filamentous cyanobacteria [Cyanonema majus n. sp., Oscillatoriopsis longa Timofeev and Hermann, 1979, and Siphonophycus robustum (Schopf, 1968) Knoll et al., 1991], and the tabulate tubular microfossil Megathrix longus L. Yin, 1987a, n. emend. Some of these taxa (e.g., H. ampliatum, C. annulare, and M. longus) have a wide geographic distribution but occur exclusively in basal Cambrian successions, supporting their biostratigraphic importance. Comparison between the stratigraphic occurrences of microfossils reported here and skeletal animal fossils published by others suggests that animals and phytoplankton radiated in tandem during the Cambrian explosion.