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    鄂西鹤峰埃迪卡拉系灯影组叠层石及其生态环境讨论

    Stromatolites of the Ediacaran Dengying Formation in Hefeng, western Hubei Province and its ecological environment discussion

    • 摘要:
      研究目的 扬子区鄂中台地埃迪卡拉系灯影组赋存丰富的叠层石,但尚未有报道对其进行系统描述。通过识别台地西南端鹤峰白果坪剖面灯影组中的叠层石种类、分析沉积环境,阐述古环境对叠层石形态分布的控制,为后续开展鄂中台地埃迪卡拉纪的叠层石研究提供参考。
      研究方法 通过剖面测量和镜下观察,于白果坪灯影组白云岩中识别出平直纹层、Stratifera层状、微波状纹层三种层状叠层石和一种Baicalia柱状叠层石。
      研究结果 研究认为上述的叠层石类型分别对应周期性暴露(前两种类型)、潟湖(微波状)和潮间带—潮下带上部(柱状)的生态位。对比与白果坪剖面灯影组同期叠层石的形态及分布规律,可知形成叠层石的微生物群落强烈受控于古水深等环境条件。层状叠层石生态区间宽,柱状及其他形态叠层石仅见于局限地区,多样性较低。
      结论 扬子区碳酸盐岩台地长期稳定的大范围潮坪环境造成的广泛分布浅水生态位和局限分布较深水生态位,是导致灯影组沉积期叠层石多样性低的主要原因。

       

      Abstract:
      This paper is the result of geological survey engineering.
      Objective The Ediacaran Dengying Formation in the Central−Hubei Platform of the Yangtze region hosts abundant stromatolites, yet there is a lack of systematic reports on them. This study aims to address this gap by identifying stromatolite types in the Dengying Formation at the Baiguoping section in the southwestern part of the platform. Through this, we analyze the sedimentary environment, aiming to elucidate the influence of the ancient environment on stromatolite distribution. The insights gained serve as a valuable reference for future research on Ediacaran stromatolites in the Central−Hubei Platform.
      Methods  Utilizing section surveys and microscopic observations, this study identifies stratiform and columnar stromatolites in the dolostones of the Ediacaran Dengying Formation at the Baiguoping section. Stratiform stromatolites include flat−laminated, Stratifera, and wavy−laminated forms, columnar stromatolite see the Baicalia form genus.
      Results  In the southwestern Central−Hubei Platform, these stromatolites are associated with various environments: Periodic exposure settings for the flat−laminated and Stratifera forms, lagoon environments for the wavy−laminated form and intertidal to upper subtidal zones for the columnar stromatolites. Published data reveals that during the deposition period of the Ediacaran Dengying Formation, stratiform stromatolites were abundant on the Yangtze Platform, meanwhile columnar and other stromatolite forms were rare, indicating limited morphological diversity.
      Conclusions  The scarcity of stromatolite variations can be attributed to widespread shallow water niches and locally deeper water niches resulting from long−term stable tidal flat environments in the Yangtze Platform.

       

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