Evidence of photosynthesis implied in oldest Banded Iron Formations (ca. 3.8 Byr-ago)
Life's history in iron - Nov. 7, 2014
Excerpt: A new study examines how Earth's oldest iron formations could have been formed before oxygenic photosynthesis played a role in oxidizing iron.,,,
Microorganisms that photosynthesize in the absence of oxygen assimilate carbon by using iron oxide (Fe(II)) as an electron donor instead of water. While oxygenic photosynthesis produces oxygen in the a...tmosphere (in the form of dioxygen), anoxygenic photosynthesis adds an electron to Fe(II) to produce Fe(III).
"In other words, they oxidize the iron," explains Pecoits. "This finding is very important because it implies that this metabolism was already active back in the early Archean (ca. 3.8 Byr-ago)."
http://phys.org/news/2014-11-life-history-iron.html
of note, there are no surviving rocks older than 3.8 Byr-ago, so this finding implies life has been present on earth from the beginning:
- Archean
Excerpt: ,,,a period of intense meteorite bombardment in the period 4.0-3.8 Ga pulverized all rocks at the Earth's surface during the period. Some think that the similar age of the oldest surviving rocks and the "late heavy bombardment" is not coincidental.
http://en.wikipedia.org/wiki/Archean |
