天津蓟县中元古界雾迷山组是一套厚度超过3000,m的叠层石碳酸盐岩沉积序列,在该序列中潮下相叠层石生物层、凝块石生物丘与潮坪相泥晶白云岩、潟湖相白云质泥页岩一起构成若干个环潮坪型米级旋回——"雾迷山旋回层"。在雾迷山组下部发育微指状叠层石,并被古生物学家定义为"Pseudogymnosolen mo-panyuensis-Scuphus-Yangzhuang columnaris"组合,即假裸枝叠层石科叠层石,沉积学家将其解释为元古代文石(灰华)海底沉淀物所构成的叠层石,代表从太古代海底结壳状文石沉淀物组成的叠层石到新元古代碎屑结构相的泥晶碳酸盐岩叠层石过渡时期的特殊产物。因此,雾迷山组巨厚的叠层石碳酸盐岩沉积序列,记录了元古代文石(灰华)海底沉淀物所构成的特殊的叠层石大规模消亡的层位,为研究前寒武纪以叠层石为代表的微生物碳酸盐岩所经历的漫长而复杂的地质历史演变提供了宝贵的材料。
The Mesoproterozoic Wumishan Formation at the Jixian section in Tianjin is a set of more than 3 000 m thick stromatolitic carbonate succession. In this succession, several lithofacies units, i. e. the subtidal stromatolitic biostrome, the thrombolitic bioherm, tidal-flat micritic dolomite and lagoon facies dolomitic mudstone and shale, make up numerous meter-scale cycles of the peritidal carbonate types that are termed as the Wumishan eyelothem. The mierodigital stromatolite which developed in the lower part of the Wumishan Formation, is defined as the "Pseudogymnosolen mopanyuensis-Scuphus-Yangzhuang columnaris" assemblage by palaeontologists. This category of stromatolites have still been interpreted as being composed of the Proterozoic aroganite (tufa) sea floor precipitates by sedimentologists, and have further been thought as the special products which were formed during the transitional period from the Arehean stromatolites making up of the sea floor aroganite precipitates to the Neoproterozoic stromatolites made up of the elastics and mieritic carbonates. Therefore, an important horizon representing the ending of the mierodigital stromatolites was recorded in the Mesoproterozoie Wumishan Formation, which provides useful information for understanding the geologic and historical evolution of microbial carbonate rocks characterized by the Preeambrian stromatolites.