1. what caused dissolved iron to rust and deposit in banded iron formations?

a. outgassing

b. oxygen released by living cyanobacteria

c. huge amounts of rain

d. an asteroid impact

2. which of these was the first source of oxygen in our atmosphere

a. oxygen produced by living things on land

b. oxygen released by volcanoes

c. oxygen released by living cyanobacteria in the ocean which then was released into the atmosphere

d. the original accretion of the earth

Oxygen released by living cyanobacteria caused dissolved iron to rust and deposit in banded iron formations. This implies the correct answer is B.

The first source of oxygen was the oxygen released by living cyanides in the ocean which then was released into the atmosphere. This implies the correct answer is C.

Question 1:

Banded iron formations are the major part of sedimentary rock. These formations are of always of the earliest part of the earth’s history also known as Precambrian age.

The general theory is that banded irons layers were developed in seawater due to the oxygen that was released by cyanobacteria. The oxygen that was released then joins with dissolve irons to form insoluble iron oxide and a thin layer on the floor of the ocean.

Most of the oldest rock formations and linked with banded iron formations and they are made up of approximately 60% of global iron reserves.  Banded iron formations can be found in the following places: United States, Ukraine, South Africa and many more.

Question 2:

The first source of oxygen is oxygen released by living cyanides in the ocean which then was released into the atmosphere.

The first microbe to produce oxygen in our atmosphere is known as Cyanobacteria. Cyanobacteria or blue-green algae produce the first oxygen about 3.5 billion years ago by photosynthesis.

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