Microfossils in bottom-hydrothermal sediments of the Saf'yanovskoe Cu-Zn deposit (Middle Urals)

Abstract

Research subject. Framboidal pyrites and sulfide micro-concretions in carbonaceous-siliceous and ore rocks of the Safyanovskoye deposit (Middle Urals). Aim. To identify the signs of vital activity of microbial communities in bottomhydrothermal deposits using the example of the Safyanovskoye sulfide deposit. The methods. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Results. TThe analyzed ore and carbonaceous-siliceous rock samples showed the presence of mineralized silicon dioxide films covering framboidal pyrites. Micro-concretions were found to consist of microfossils of filamentous organisms and framboids. Pyrite samples included the remains of tubular casts of sulfidized vestimentifera and polychaetes, associated with framboids. The possibility of using fossilized remains of microbial communities for distinguishing bottom-hydrothermal facies among pyrite deposits was confirmed. Conclusions. Hydrothermal-sedimentary deposits are characterized by the traces of specific microbial communities, since prokaryotic organisms were pioneers in hydrothermal oases. Their long active existence created a basis for the second trophic link, i.e. filter feeding macrofauna and endosymbiotrophs. These organisms, in turn, formed another level in the food chain of the trophic pyramid. It is believed that micro-concretions and framboidal pyrites are indicators of the vital activity of microbial communities.