What large-scale event in Earth's history led to the creation of Banded Iron Formations?
Answer
Oxygen first began to accumulate in the atmosphere, causing dissolved iron in the oceans to precipitate
BIFs formed during a massive event when rising atmospheric oxygen caused iron dissolved in the oceans to precipitate out as iron oxides.

Related Questions
What is the frequently cited estimate for how long accessible iron ore reserves will last at current global consumption rates?How are geological iron *reserves* defined by geoscientists and mining analysts?What do geological iron *resources* include that reserves typically exclude?What ancient geological structure is the source of most commercially mined iron ore?Roughly how old are the Banded Iron Formations (BIFs) that constitute major iron ore deposits?What large-scale event in Earth's history led to the creation of Banded Iron Formations?What is the primary factor that limits the longevity of usable iron supply despite the element's abundance on Earth?If global iron ore production remained flat at the 2012 level of 2.5 billion tonnes, how long would the measured reserves of 150 billion tonnes last?Which iron oxide ore is highly sought after because it can reach an iron content up to 70% and requires relatively low initial processing?What critical countermeasure offers genuine long-term sustainability for the supply of usable iron?