Role of Bacteria in the Accumulation of Cambrian–Ordovician Phosphate-Bearing Obolus Beds in the North-West of the Russian Plate

Like many phosphorite deposits in the world, the Baltic Middle Cambrian and Lower Ordovician phosphate-bearing basin owes its origin primarily to microbial activity. Colossal accumulations of valves and detritus of lingulates (phosphate brachiopods, mainly from the orders Lingulida and Acrotretida) are the main sources of phosphate material in this basin. The fossilization of the valves of these brachiopods was based on their early postmortem mineralization, which made the valves resistant to destruction. Bacteria were the drivers of this process. This was followed by transfer, breaking, redeposition, and accumulation of the valves and valve fragments in suitable areas of the sea