Which process drives the formation of banded iron formations in Precambrian lake deposits?

💡 Explanation

When cyanobacteria photosynthesize, they release oxygen which oxidizes dissolved ferrous iron (Fe2+) in the lakes, causing it to precipitate as insoluble ferric oxide (Fe3+) layers. Therefore, seasonal blooms cause iron formation, rather than uplift, hydrothermal vents, or glacial deposition, which involve different iron sourcing mechanisms.

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