Microconchids from microbialites near the Permian-Triassic boundary in the Zuodeng Section, Baise area, Guangxi Zhuang Autonomous Region, South China and their paleoenvironmental implications
Microconchids from microbialites near the Permian-Triassic boundary in the Zuodeng Section, Baise area, Guangxi Zhuang Autonomous Region, South China and their paleoenvironmental implications
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DOI：
10.1007/s12583-015-0554-7
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发表时间：
2015-04
影响因子：
3.3
通讯作者：
Hao Yang;Zhong‐Qiang Chen;Weiquan Ou
中科院分区：
文献类型：
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作者：
Hao Yang;Zhong‐Qiang Chen;Weiquan Ou
在广西壮族自治区百色地区左邓剖面靠近二叠系-三叠系界线的微生物岩沉积物中提取了大量的微贝类蠕虫管。分别使用光学显微镜和灵敏电子显微镜（SEM）在岩相薄片和分离标本中研究了这些钙质蠕虫管。它们分为两种形态类型：螺旋盘绕管和平面螺旋盘管，可归为Microconchus aberrans（Hohenstein，1913）和M。 utahesis（Zatoń 等人，2013）。管壁超微结构的特征是层状微晶，这将所研究的微贝类与通常具有晶石纹理的壳超微结构的类似微腹足类或多毛类动物区分开来。绝大多数来自微生物岩的微贝类具有平面螺旋盘管。现存的、形态趋同的螺类的生活方式表明，这些平面螺旋卷曲的微贝类可能已经在一些当地的含氧绿洲中定居，这些绿洲可能是由贫氧微生物岩生态系统中的光合蓝细菌产生的，在这些绿洲中，它们可能密集地定居在其中，在不同个体之间以及与其他相关动物之间对耗氧量和食物来源的激烈竞争中。二叠纪-三叠纪生物危机之后微生物岩生态系统的有害环境状况也可以通过同一剖面发出的各种地球化学信号来指示。这种有害的栖息地可能不适合大多数后生动物，但它有一些当地的含氧绿洲，有利于机会性类群的栖息。
Abundant microconchid worm tubes were extracted from the microbialites deposit near the Permian-Triassic boundary at the Zuodeng Section, Baise area, Guangxi Zhuang Autonomous Region, South China. These calcareous worm tubes were studied in both petrographic thin sections and isolated specimens using optical microscope and sensitive electronic microscope (SEM), respectively. They are categorized into two morphological types: helically coiled and planispirally coiled tubes, which are assignable toMicroconchus aberrans(Hohenstein, 1913) andM. utahesis(Zatoń et al., 2013), respectively. The tube wall ultrastructure is characterized by laminated micrites, which distinguish the studied microconchids from comparable microgastropods or spirorbid polychaete that usually has shell ultrastructure of spar texture. The overwhelm majority of microconchids from the microbialite possess the planispirally coiled tubes. The lifestyle of extant, morphologically convergent spirorbids suggests that these planispirally coiled microconchids may have colonized in some local oxygenic oases probably produced by photosynthetic cyanobacteria in the oxygen-poor microbialite ecosystem in which they may have settled densely with high competition among various individuals and with other associated animals for oxygen consumption and food soucres. The deleterious environment condition of the microbialite ecosystem immediately after the Permian-Triassic biocrisis is also indicated by various geochemical signals derived from the same section. Such a deleterious habitat may be inhospitable for most metazoans, but it has some local oxygenic oases that was favorable for opportunistic taxa to dwell.