Earth´s earliest mappable ecosystem

南非的巴伯顿绿岩带包含了一个非常高分辨率的中侏罗世（穆迪群，~3.2 Ga）记录，主要是近岸沉积环境，保存了广泛的，形态多样的微生物生物群。这些生物垫代表了最古老的已知的保存完好的可映射生物介质单元;任何更古老的生命迹象要么局限于露头规模（或更小），要么表现出低形态多样性（例如，条带状碳质硅质岩）。此外，以前的微生物生命迹象仅见于碳酸盐、深水或碳酸盐环境。微形态和生物垫的范围取决于相，并适应于中等至高能量的桑迪和砾石，无泥海岸线。微生物席由同位素轻干酪根组成，并显示出细胞结构的残余;其内部复杂性，代谢和生态是本提案的主题。丰富的球根和圆顶结构表明捕获代谢气体和可能的趋光行为。巨大的年龄、多样的形态、丰富度、可绘制的范围、相当程度的保存和明确的古环境使这些席成为研究化学成分、（微）地层结构和沉积相的理想对象。我相信，这一提议有可能扩大我们对地球上和其他地方早期生命栖息地的了解，限制早期代谢途径，并有助于我们对生物多样性，早期生命战略和氧气上升的了解。

The Barberton Greenstone Belt, South Africa, contains a very‐high‐resolution record of Middle Archaean (Moodies Group, ~3.2 Ga), dominantly nearshore depositional environments which preserve an extensive, morphologically diverse microbial biota. These biomats represent the oldest‐known well‐preserved mappable biomediated units; any older signs of life are either restricted to outcrop‐scale (or smaller) or show low morphological diversity (e.g., banded carbonaceous cherts). In addition, previous signs of microbial life are known only from carbonate, deep‐water or evaporitic environments.Micromorphology and extent of the biomats is facies‐dependent and adapted to medium‐ to high‐energy sandy and gravelly, mud‐free shorelines. Microbial mats are composed of isotopically light kerogen and show remnants of cellular structures; their internal complexity, metabolism and ecology is subject of this proposal. Abundant bulbous and domal structures suggest trapping of metabolic gases and possibly phototactic behavior. The great age, diverse morphology, abundance, mappable extent, fair degree of preservation and well‐defined paleoenvironments makes these mats an ideal object to study chemical composition, (micro‐)stratigraphic architecture and sedimentary facies. I believe that this proposal holds the potential to expand our knowledge of early life habitats on Earth and possibly elsewhere, constrain early metabolic pathways, and contribute to our knowledge of biologic diversification, early strategies of life and the rise of oxygen.