Banded Iron Formations: The Evolution of Earth’s Surface and Life Mike Tice 6 August 2009

Earth History

The Most Important Organisms in Earth History: The Cyanobacteria! Bacteria The first organisms to produce oxygen during photosynthesis The ultimate source of all oxygen in our atmosphere

Banded Iron Formation

This is a photograph of a slab of banded iron formation cut with a rock saw.

This image uses color to represent the composition of a small part of the slab. Here, red represents the element Fe.

Is this piece of banded iron formation more like a shale or a conglomerate? Why are they similar? shaleconglomerate

Model of BIF Deposition Dissolved iron (and no oxygen) in the deep ocean Cyanobacteria producing oxygen in the shallow ocean

Another Model of BIF Deposition Dissolved iron (and no oxygen) in the deep ocean UV light passing through the upper atmosphere with no ozone layer UV light

Another Model of BIF Deposition Dissolved iron (and no oxygen) in the deep ocean Non-oxygen producing (anoxygenic) photosynthetic bacteria in shallow water anoxygenic bacteria

Questions What do banded iron formations tell us about changing environments in the Earth’s oceans? What do banded iron formations tell us about the evolution of photosynthesis? How were changing conditions in the atmosphere and oceans related in time? How would organisms living in the shallow and deep oceans have reacted to changing environmental conditions?