Algoma-type banded-iron formation deposit

Algoma-type banded-iron formations (BIFs) are chemically precipitated sediments, typically thin-bedded, containing at least 15 percent iron of sedimentary origin along with layers of quartz. These formations are generally older than 1.7 billion years and are often metamorphosed. Unlike Lake Superior-type BIFs, Algoma-type BIFs lack lateral continuity in their layers and are found within rock sequences containing significant amounts of submarine volcanic rocks. It is widely accepted that these deposits formed due to submarine volcanism, supported by observations of iron-rich, chemically precipitated siliceous layers near seafloor hot springs. These deposits formed over a broad time range, from 3.8 billion to a few hundred million years ago.12