Abstract Microbial mats were well established and widespread during the Proterozoic eon, playing a pivotal role in atmospheric oxygen content. In this study, microbial mats were systematically investigated from the 1600 Ma to 1400 Ma Jixian Group, North China. Three types of microbial mats were recognized, including Microbial Mat dominated by Filaments (MMF), Microbial Mat dominated by Coccoids (MMC), Microbial Mat dominated by Filaments and Coccoids (MMFC). These microbial mats were mainly built by Siphonophycus kestron, Siphonophycus solidum, Myxococcoides sp. and Coniunctiophycus majorinum. Due to in situ preservation, five sedimentary structures related to photosynthesis and oxygen release were discovered in these microbial mats. The alternating light-dark laminae and bottleneck structure may be caused by immediate mineralization and phototropism of filaments in a hypersaline environment. Bubble structure, fenestrae structure and hourglass structure probably were related to oxygen release, and their emergence fill the gap between oxygenic photosynthesis of microbial mat and atmospheric oxygen content in Proterozoic eon.

中文翻译：

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华北中元古代蓟县群微生物席的新研究：光合作用和氧气释放的证据

摘要 微生物垫在元古宙时期已经建立并广泛分布，在大气氧含量中起着关键作用。在这项研究中，系统地调查了华北 1600 Ma 至 1400 Ma 季县群的微生物席。识别出三种类型的微生物垫，包括以细丝为主的微生物垫（MMF）、以球状体为主的微生物垫（MMC）、以细丝和球状体为主的微生物垫（MMFC）。这些微生物垫主要由 Siphonophycus kestron、Siphonophycus solidum、Myxococcoides sp。和 Coniunctiophycus majorinum。由于原位保存，在这些微生物垫中发现了五种与光合作用和氧气释放有关的沉积结构。交替的明暗纹层和瓶颈结构可能是由高盐环境中细丝的直接矿化和向光性引起的。气泡结构、窗孔结构和沙漏结构可能与氧的释放有关，它们的出现填补了元古代时期微生物垫的含氧光合作用与大气氧含量之间的空白。