Morphological adaptations of 3.22 Ga-old tufted microbial mats to Archean coastal habitats (Moodies Group, Barberton Greenstone Belt, South Africa)
Morphological adaptations of 3.22 Ga-old tufted microbial mats to Archean coastal habitats (Moodies Group, Barberton Greenstone Belt, South Africa)
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DOI：
10.1016/j.precamres.2015.04.018
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发表时间：
2015-09-01
影响因子：
3.8
通讯作者：
Tice, Michael M.
中科院分区：
文献类型：
--
作者：
Homann, Martin;Heubeck, Christoph;Tice, Michael M.
微生物生命在古太古代就已广泛存在并广泛存在。然而，当时进化进步的程度，如微生物运动、物种内和物种间相互作用、向光性或含氧光合作用仍然存在很大争议。位于巴伯顿绿岩带（南非 BGB）的 3.22 Ga 穆迪群是地球上保存完好的最古老的硅质碎屑潮汐沉积物。它们展示了独特的微生物垫组合，为破译微生物群落对不同古环境设置的形态适应提供了绝佳的机会。化石垫以干酪质层状（0.5-1 毫米厚）的形式保存下来，可以在约 1000 米厚的细粒至粗粒潮汐砂岩和砾岩序列中横向追踪约 15 公里。我们在这里提出了详细的地层和沉积褪色分析，记录了三种主要垫形态类型与特定环境背景的关联：（1）沿海洪泛区的平面型，（2）潮间带的波状型，以及（3）上部潮间至潮上相的簇状型。所有垫层类型都表明光养生物群蓬勃发展；此外，簇状形态表明现代环境中蓝藻垫具有复杂的协调生长水平。 (C) 2015 Elsevier B.V. 保留所有权利。
Microbial life was well established and widespread by the Paleoarchean; however, the degree of evolutionary advancement such as microbial motility, intra- and inter-species interactions, phototropism, or oxygenic photosynthesis by that time remains highly debated. The 3.22 Ga Moodies Group in the Barberton Greenstone Belt (BGB, South Africa) are Earth's oldest well-preserved siliciclastic tidal deposits. They exhibit a unique assemblage of microbial mats, providing an excellent opportunity to decipher the morphological adaptations of microbial communities to different paleoenvironmental settings. The fossil mats are preserved as kerogenous laminations (0.5-1 mm thick) that can be traced laterally for similar to 15 km in a similar to 1000 m-thick succession of fine- to coarse-grained tidal sandstones and conglomerates. We here present a detailed stratigraphic and depositional fades analysis, documenting the association of the three principal mat morphotypes with specific environmental settings: (1) planar-type in coastal floodplain, (2) wavy-type in intertidal, and (3) tufted-type in upper inter- to supratidal facies. All mat types indicate a flourishing phototrophic biota; moreover, the tufted morphology suggests an intricate level of coordinated growth commonly known from cyanobacterial mats in modern environments. (C) 2015 Elsevier B.V. All rights reserved.