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首页> 外文期刊>Journal of Palaeogeography >The response of stromatolites to seismic shocks: Tomboliths from the Palaeoproterozoic Chaibasa Formation, E India
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The response of stromatolites to seismic shocks: Tomboliths from the Palaeoproterozoic Chaibasa Formation, E India

机译：叠层石对地震的响应：印度东部古元古代Chaibasa组的块状岩

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Abstract It is demonstrated here for the first time how Palaeoproterozoic stromatolites survived seismic disturbance of their substrate. The stromatolites under study could have been cyanobacteria or any other photoautotrophic microbes, which formed mats that covered a substrate of very fine-grained sandstones and mudstones of the Chaibasa Fm. in eastern India. The sediments represent a shelf environment. The local abundance of the stromatolites suggests that the low-energy environment formed a suitable habitat. The common phases of tectonic quiescence were, however, occasionally interrupted by seismic shocks. These were sufficiently strong to deform the mat layers, the lower parts of which might already have been (semi-) consolidated. The mats became partly folded, partly faulted, and already consolidated parts of the stromatolite layers broke off. This can be deduced from the angular shapes of part of the broken-off fragments. It appears, however, that part of these fragments were still sufficiently soft to become rounded and deformed by rolling over the seafloor, probably under the influence of tidal currents. When come to rest, these fragments served as a new substrate for new generations of the micro-organisms. These micro-organisms thus survived by continued growth on the reworked fragments and built up new stromatolites that may show an ‘angular disconformity’ with the stromatolites of their substrate. It thus is shown that stromatolites have an adequate response to a sudden disturbance of their habitat, and that they survive earthquakes by colonization of broken-off fragments. We call the ‘healed’ fragments ‘tomboliths’ (tumbled stones).
机译：摘要本文首次证明了古元古代叠层石如何在其基底的地震扰动中幸存下来。研究中的叠层石可能是蓝细菌或任何其他自养微生物，它们形成的垫层覆盖了Chaibasa Fm的非常细粒度的砂岩和泥岩。在印度东部。沉积物代表架子环境。叠层石的局部丰度表明低能环境形成了合适的栖息地。但是，构造静止的公共阶段偶尔会因地震而中断。这些足够坚固以致使垫层变形，而垫层的下部可能已经（半）固结。垫子被部分折叠，部分断层，并且层结石层中已经固结的部分破裂了。这可以从折断的碎片的一部分的角度形状中得出。但是，这些碎片的一部分似乎仍然足够柔软，可能在潮流的影响下通过在海底上滚动而变得圆润和变形。当它们静止时，这些片段成为新一代微生物的新底物。这些微生物因此通过在重新加工的碎片上继续生长而得以幸存，并建立了新的叠层石，这些叠层石可能与其基质的叠层石呈“角度不一致性”。因此表明，叠层石对生境的突然扰动具有适当的响应，并且通过破碎碎片的定殖而在地震中幸存下来。我们将“愈合”的碎片称为“碎石”（碎石）。

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