辽宁大连金州寒武系苗岭统出露的微生物礁, 发育在三级沉积层序的高位体系域中。宏观上, 这些微生物礁表现为无特殊内部构造的泥晶组构, 与叠层石、鲕粒灰岩或核形石灰岩形成碳酸盐岩复合体。通过偏光显微镜对微生物礁进行详细观察, 发现了微凝块、钙化微生物、底栖鲕粒和多种泥晶化组构。钙化微生物包括 Girvanella (葛万菌)、Renalcis (肾形菌)、Tarthina、Epiphyton (附枝菌)及可能的Angulocellularia (角胞菌)。葛万菌呈现出四种生长习惯, 可见葛万菌聚合体和肾形菌聚合体。不同层位钙化微生物类型的差异可能与沉积环境的差异有关。研究区内存在的各种钙化微生物, 与发生泥晶化或白云石化的钙化微生物及含黄铁矿的组构一起, 表明了微生物礁形成过程中光合自养生物和异养硫酸盐还原细菌的重要作用, 同时也表明了钙化微生物的保存不仅与早期石化作用有关, 还与成岩过程中异养细菌的作用有着密切的关系。大连金州苗岭统微生物礁为钙化微生物主导的礁提供了实例。

The Cambrian Miaolingian microbial reefs exposed at the Jinzhou section, Dalian, Liaoning Province were developed in the highstand system tract of third-order depositional sequences. Macroscopically, these microbial reefs lack distinctive internal structures and mainly consist of micrites, forming carbonate rock complexes with associated stromatolites, oolitic grainstones, and oncolitic grainstones. Microscopically, observations under a polarizing microscope reveal the presence of microclots, calcified microbes, benthic oolites, and various micritized structures within the microbial reefs. The calcified microbes include Girvanella, Renalcis, Tarthina, Epiphyton, and possible Angulocellularia. Girvanella exhibits four growth habits, and both Girvanella and Renalcis aggregates are present. Variations in the composition of calcified microbial groups in different layers may be related to the changes of sedimentary environments. The calcified microbes in the study area, together with the micritized or dolomitized calcified microbes and associated pyrites in different microbial structures, indicate that both photoautotrophs and heterotrophic sulfate-reducing bacteria played important roles in the formation of the microbial reefs. These features also suggest that the preservation of calcified microbes is not only controlled by early lithification but also is closely linked to heterotrophic bacterial activities during diagenesis. The Cambrian Miaolingian microbial reefs at the Jinzhou section provide an example of reefs dominated by calcified microbes.

国家自然科学基金项目(41472090)和东华理工大学博士启动基金(DHBK2019258)联合资助