Proponents of the hypothesis argue that the reappearance of BIF in the sedimentary record is a result of limited oxygen levels in an ocean sealed by sea - ice .
Opponents suggest that the rarity of the BIF deposits may indicate that they formed in inland seas .
Proponents of the hypothesis argue that the reappearance of BIF in the sedimentary record is a result of limited oxygen levels in an ocean sealed by sea - ice , while opponents suggest that the rarity of the BIF deposits may indicate that they formed in inland seas .