Constructive and Destructive Role of Organisms in the Formation of Microoncolites from the Vendian Tinnov Formation of the Baikal–Patom Uplift in Eastern Siberia

This paper analyzes the processes of formation of Vendian microoncolites from Eastern Siberia in Russia, which were studied with two different complementary methods using an electron microscope. In each of the six identified types, which significantly differ in structure and microstructure, we have established microorganisms that are characteristic exclusively of this type. Coccoid and filamentous microfossils and filamentous and yeast aquatic fungi have been identified. The patterns of their distribution and characteristics of the material cementing the microorganisms are analyzed in each type of microoncolite. The role of cyanobacteria in the construction of different microoncolites is discussed. The consequences of degradation of the primary biogenic structure in one of the types of buildups created by yeast fungi have been revealed.