Bacterial, fungal, and algal microfossils in the Lower Proterozoic Baikal region of Siberia (Udokan and Sayany Mountains)

Microfossils from metamorphized Lower Proterozoic deposits of the Udokan Mountains (Naminga Formation) and Sayany Region (Daldarma Formation) are investigated in preparations and petrographic thin sections. They include leucoxenized and ferruginous threads varying in size (50–500 μm) and thread accumulations, which are compared to cyanobacteria. Mineralized thalli probably belong to algae. Small, rounded forms from carbonaceous beds are treated as iron and chemolithotrophic bacteria of stagnant zones of paleobasins. Round or pear-shaped nontransparent forms with projections or several fused forms are described from preparations and identified as fungal microfossils. Similar forms have been recorded in the Lower Proterozoic of Karelia.