Which of the following statements about the banded iron formations is true?
A)The BIFs show evidence of an oxygen-poor atmosphere because all of the oxygen was dissolved into the oceans and then precipitated as iron-oxide minerals.
B)The BIFs show evidence of an acidic ocean that forced iron to bond with the oxygen in the water to form iron-oxide minerals.
C)The BIFs show evidence of an oxygen-poor ocean because all the oxygen was trapped in the iron-oxide minerals that make up the formation.
D)The BIFs show evidence of an oxygen-rich atmosphere that forced the oceans to become oxidizing and precipitate iron-oxide minerals.

Question

Quizplus · Accepted Answer

The banded iron formations (BIFs) are sedimentary rocks composed of alternating layers of iron-rich minerals and iron-poor minerals. They are believed to have formed during Earth's early history when the atmosphere was becoming oxygen-rich, and the oceans were becoming oxidizing. This oxygen-rich atmosphere forced the oceans to precipitate iron-oxide minerals, which formed the BIFs. Therefore, the BIFs show evidence of an oxygen-rich atmosphere. None of the other options provide a correct explanation for the formation of BIFs.

Which of the Following Statements About the Banded Iron Formations