The dynamic influence of microbial mats on sediments: fluid escape and pseudofossil formation in the Ediacaran Longmyndian Supergroup, UK
The dynamic influence of microbial mats on sediments: fluid escape and pseudofossil formation in the Ediacaran Longmyndian Supergroup, UK
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微生物垫对沉积物的动态影响：英国埃迪卡拉龙明典超群中的流体逃逸和假化石形成
DOI：
10.1144/jgs2015-036
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发表时间：
2015
影响因子：
2.7
通讯作者：
Menon L
中科院分区：
文献类型：
--
作者：
Menon L
人们认为，在生物扰动出现之前，微生物垫就已经在海洋环境中广泛存在，并且它们对沉积物的影响范围正逐渐被人们所认识。我们认为垫密封可以动态地影响孔隙水条件，并允许超压的积累，从而驱动脱水和脱气，从而产生一系列非典型的流体逸出特征。来自那里的细层粉质和砂质纹层。 560 英国什罗普郡 Longmyndian 超群的 Ma Burway 组揭示了沉积物注入的证据，包括破碎的层理、碎屑注入、基台状特征和亚毫米级的沉积火山。这些特征与微生物基质的褶皱薄片诊断相关。与基质相关的沉积物注入可以解释几种神秘的盘状印记的形成，这些印记常见于这个时代的岩石中，以前被认为是埃迪卡拉生物群的产物。之前描述为 Medusinitesaff.asteroides 和 Beltanelliformis 的 Longmyndian 形式的连续研磨表明，这种盘状特征可以通过流体逸出和相关的负载结构来充分解释。我们的观察强调了浅海埃迪卡拉沉积物的非现实性质。与基质相关的沉积物注入特征为解释元古代岩石及其神秘盘状标记的生物成因性提供了新的见解。补充材料包含在 Ashes Hollow 上部 Burway 地层中观察到的流体逸出和加载特征的进一步图像的文件，以及一个典型垂直横截面中出现的特征的注释图，可从 www.geolsoc.org.uk/SUP18870 获取。
Microbial mats are thought to have been widespread in marine settings before the advent of bioturbation, and the range of their influence on sediments is gradually becoming recognized. We propose that mat sealing can dynamically affect porewater conditions, and allow the build-up of overpressure that can drive dewatering and degassing to produce a suite of atypical fluid-escape features. Finely bedded silty and sandy laminae from thec. 560 Ma Burway Formation of the Longmyndian Supergroup, Shropshire, England, reveal evidence for sediment injection, including disrupted bedding, clastic injections, sill-like features and sediment volcanoes at sub-millimetre scale. These features are associated with crinkly laminae diagnostic of microbial matgrounds. Matground-associated sediment injection can explain the formation of several types of enigmatic discoidal impressions, common in rocks of this age, which have previously been attributed to the Ediacaran macrobiota. Serial grinding of Longmyndian forms previously described asMedusinitesaff.asteroidesandBeltanelliformisdemonstrates that such discoidal features can be fully explained by fluid escape and associated load structures. Our observations emphasize the non-actualistic nature of shallow-marine Ediacaran sediments. Matground-associated sediment injection features provide a new insight into the interpretation of Proterozoic rocks and the biogenicity of their enigmatic discoidal markings.Supplementary materialsA document containing further images of fluid escape and loading features observed in the upper Burway Formation at Ashes Hollow, together with an annotated diagram of features appearing in one typical vertical cross-section, is available at www.geolsoc.org.uk/SUP18870.
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发表时间：
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期刊：
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发表时间：
1984
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影响因子：
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影响因子：
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