Filamentous cyanobacteria fossils and their signifi-cance in the Permian-Triassic boundary section at Laolongdong,Chongqing  

Filamentous cyanobacteria fossils and their signifi-cance in the Permian-Triassic boundary section at Laolongdong, Chongqin

作　　者：JIANG HongXia WU YaSheng CAI ChunFang 

机构地区：[1]Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China

出　　处：《Chinese Science Bulletin》2008年第12期1871-1879,共9页

基　　金：the National Natural Science Foundation of China (Grant No.40472015);State Key Laboratory of Geological Processes and Mineral Re-sources China University of Geosciences, Wuhan (Grant No.GPMR2007-01);the Science Foundation of China Postdoctors (Grant No.20070420523)

摘　　要：The microbial communities blooming immediately after the end-Permian mass extinction represent abnormally extreme environments, and vary in different areas. In this study, filamentous cyanobacterial biota was found in the strata after the extinction in the famous Permian-Triassic boundary section at Laolongdong, Chongqing, southwest China. In thin sections, the filamentous cyanobacterial fossils are below 1 mm in length, and generally taper to one end, with the widest diameter up to 0.08 mm. Some of them are curved, indicating that they are soft in life. Their walls are composed of cryptocrystalline to microcrystalline calcites. The filaments have round cross section, and are internally filled with micrites and fine sparry calcites, which indicate that the filaments are originally empty. They are randomly dis-tributed in the rocks, but in some places, they tend to be distributed in radial pattern. The filamentous organisms are morphologically similar to Rivularia of Rivulariaceae, Cyanobacteria Phylum, but with calcified sheaths, and are tentatively regarded as an indeterminate new species in Rivularia: Rivularia sp. Cyanobacteria are photosynthetic autotrophic, and can survive in dysoxic condition. The blooming of this organism and the absence of other organisms may indicate that the environment was oxygen- deficient and shallow, since this photosynthetic autotrophic organism needed to live within photic zone.The microbial communities blooming immediately after the end-Permian mass extinction represent abnormally extreme environments, and vary in different areas. In this study, filamentous cyanobacterial biota was found in the strata after the extinction in the famous Permian-Triassic boundary section at Laolongdong, Chongqing, southwest China. In thin sections, the filamentous cyanobacterial fossils are below 1 mm in length, and generally taper to one end, with the widest diameter up to 0.08 mm. Some of them are curved, indicating that they are soft in life. Their walls are composed of cryptocrystalline to microcrystalline calcites. The filaments have round cross section, and are internally filled with micrites and fine sparry calcites, which indicate that the filaments are originally empty. They are randomly distributed in the rocks, but in some places, they tend to be distributed in radial pattern. The filamentous organisms are morphologically similar to Rivularia of Rivulariaceae, Cyanobacteria Phylum, but with calcified sheaths, and are tentatively regarded as an indeterminate new species in Rivularia： Rivularia sp. Cyanobacteria are photosynthetic autotrophic, and can survive in dysoxic condition. The blooming of this organism and the absence of other organisms may indicate that the environment was oxygendeficient and shallow, since this photosynthetic autotrophic organism needed to live within photic.

关 键 词：蓝藻 化石 植物 二叠纪 古生物学 

分 类 号：Q914.2[天文地球—古生物学与地层学]