First thing, I didn't say that the article was about life on Earth. I was making the point that since the presence of the iron deposits required the presence of life. I was using the stated age of the deposits to demonstrate the early appearance of life on Earth.
Well, to back up my statements I have just been running through Google looking for more about the age of the deposits. So far I can't find anything that actually points to the oldest deposits being around 4 billion years old, which is what it said in the link. That kind of casts into doubt my assumption that life must have been available by that time. The oldest times I can find right off hand for life on Earth are in the range of 3.6 to 3.8 billion years ago. So this seems to be a safe time for the formation of life. Of course if the 4 billion years for the first iron deposits is true it pushes life back by another 200 to 400 million years. There is pretty good evidence of life on earth in large quantities by 3.7 billion years ago.
Now then about your other mechanisms for producing oxygen. I wonder if there could be enough water cracked to release the amount of oxygen required to produce the amount of iron ore we have. Keep in mind that as soon as hydrogen came into contact with any oxygen it would start reverting to water. What would cause hydrogen be sequestered in the rocks while the oxygen was being released into the water? At first glance it seems that both would be held or released pretty much the same. Thinking just a little bit further, it is harder to contain hydrogen than it is oxygen. Hydrogen will leak through almost anything, so it would seem that the hydrogen might be released more easily than the oxygen.
Bill Gill
