Lower Ordovician Stromatolite Bioherms from the Moyero River Key Section (Tunguska Syneclise, Eastern Siberia)

Stromatolite bioherms were found in the Lower Ordovician sediments of the Moyero River section (Tunguska syneclise, Eastern Siberia). Their structure is considered based on the example of their typical buildup and adjacent sediments. It is revealed that the studied sediments were formed during the development of both bacterial communities (primarily cyanobacteria) and calcareous algae. The presence of remains of calcareous algae Nuia of different preservation in bioclastic–oolitic and oolitic–bioclastic limestones underlying stromatolite buildups and composing interbioherm sediments is established. It is assumed that the formation of stromatolite bioherms and surrounding sediments was controlled by sea level fluctuations that were reflected in the transgressive–regressive cyclicity and changes in sedimentation conditions.