The Precambrian time (before 540 Ma) experienced extensive and severe glaciations spanning millions of years of geological history, known as Snowball Earth. Cryogenian glaciations (720–635 Ma) were prerequisites to the Ediacaran blooming of life (635–543 Ma), and although broad attention is devoted to marine ecosystems, the debate on how terrestrial ecosystems (for instance soil formation) were built up after global glaciations is still missing. I suggest that cryoconite, a fine, dark mineral sediment mixed with organisms and covering ice surfaces around the world, could be a key factor in shaping Precambrian terrestrialization. Cryoconite on modern glaciers commonly evolves into biological aggregates facilitated by cyanobacteria. These tiny granules host aerobic and anaerobic organisms, they are biogeochemically active, store organic matter including humic substances, and are common at the glacier snout. The Precambrian scenario presented here comprises the export and deposition of biochemically active cryoconite granules to bare rocks after glacier retreat, far inland of the supercontinent Pannotia. This process started biological Neoproterozoic terrestrialization including seeding of organisms in barren forefields, weathering of parent rocks, pedogenesis, and evolution of main freshwater and terrestrial phylogenetic lineages. Observations of the ecotone between the modern glacier snout and forefield allow to reconstruct the processes of building the first terrestrial ecosystems after Neoproterozoic glaciations.

中文翻译：

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新元古代雪球地球之后，冰川表面的生物聚集体是否引发了陆地环境中的生命播种和成土作用？


前寒武纪（540 Ma之前）经历了跨越数百万年地质历史的广泛而严重的冰川作用，被称为雪球地球。低温冰川作用（720-635 Ma）是埃迪卡拉生命繁盛（635-543 Ma）的先决条件，尽管人们广泛关注海洋生态系统，但关于陆地生态系统（例如土壤形成）如何在全球范围内建立起来的争论冰川仍然缺失。我认为冰石是一种细小的、深色的矿物沉积物，与生物体混合并覆盖世界各地的冰面，可能是塑造前寒武纪陆地化的关键因素。现代冰川上的冰石通常会在蓝细菌的促进下演变成生物聚集体。这些微小的颗粒承载着需氧和厌氧生物，它们具有生物地球化学活性，储存包括腐殖质在内的有机物，并且在冰川口处很常见。这里介绍的前寒武纪情景包括在冰川退缩后，生化活性的冰石颗粒输出并沉积到裸露的岩石上，位于潘诺蒂亚超大陆的内陆深处。这一过程开始了生物新元古代陆地化，包括在贫瘠的前田中播种生物、母岩的风化、土壤发生以及主要淡水和陆地系统发育谱系的进化。对现代冰川口和前场之间的交错带的观测可以重建新元古代冰川作用后第一个陆地生态系统的构建过程。