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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
https://eapbiofield.wikispaces.com/file/detail/I11-30-cyanobacteria.jpg
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.
This is a photograph of a slab of
banded iron formation cut with a rock
saw.
• Is this piece of banded
iron formation more
like a shale or a
conglomerate?
• Why are they similar?
shale
http://commons.wikimedia.org/wiki/File:Limestone_on_shale.jpg
conglomerate
http://en.wikipedia.org/wiki/File:Lehigh_conglom.jpg
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
UV light
• Dissolved iron (and no oxygen) in the deep
ocean
• UV light passing through the upper
atmosphere with no ozone layer
Another Model of BIF Deposition
anoxygenic bacteria
• Dissolved iron (and no oxygen) in the deep
ocean
• Non-oxygen producing (anoxygenic)
photosynthetic bacteria in shallow water
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?