Copper offers novel clues to ancient Earth's "Great Oxidation Event"

Discussion in 'Chemistry' started by Plazma Inferno!, Apr 25, 2016.

  1. Plazma Inferno! Ding Ding Ding Ding Administrator

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    Roughly 2.4 billion years ago, oxygen gas began suffusing Earth’s atmosphere in what scientists call the Great Oxidation Event. Much remains uncertain about this critical moment in history, but now researchers find that copper in ancient sediments could help track how oxygen levels have fluctuated in the past.
    Although oxygen gas currently makes up about a fifth of the air we breathe, there was little if any oxygen in the primordial atmosphere. Significant levels of the gas started permanently building up in our atmosphere with the Great Oxidation Event, most likely due to the biochemical activities of cyanobacteria—microbes that, like plants, photosynthesize and exhale oxygen. The rise of oxygen then helped support the evolution of oxygen-breathing life.
    According to the authors, the Great Oxidation Event set the stage for the initiation of the evolution of complex life that eventually led to the appearance of higher animals that use oxygen as a fuel to burn food to generate energy.

    http://blog.pnas.org/2016/04/journa...lues-to-ancient-earths-great-oxidation-event/
     
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  3. exchemist Valued Senior Member

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    All rather obscure, but I suppose another piece of evidence to date the Great Oxygenation Event, which is what it seems to be generally called.

    I must say find the term "Great Oxidation Event", which these writers use, rather confusing or even potentially misleading. Since the net effect of it was liberation of free oxygen, I'd have thought it would be better thought of as a reduction event (reduction, that is, of CO2 to (H2CO)n - carbohydrate- by photosynthesis), rather than an oxidation event.

    I suppose the appearance of free oxygen would have led to subsequent oxidation of various minerals so these, it is true, would give the appearance of a great oxidation. But to me, the fact that the Earth/atmosphere system, as a whole, went from one in which all the oxygen was bound in compounds to one in which a great deal of it was free, elemental oxygen, means that it has to be seen as an overall reduction process for the planet.
     
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  5. timojin Valued Senior Member

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    I don't how old is the story of Genesis 1 day ==== years or 2 or 3 billion year
    Genesis 1 ; 11 And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so.
    12 And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good.
    13 And the evening and the morning were the third day. OR so many bions of year for our time
    CONTINUING EVOLUTION
    20 And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.
    21 And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.
    22 And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.
    23 And the evening and the morning were the fifth day.
    24 And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.
    25 And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.
    26 And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
    27 So God created man in his own image, in the image of God created he him; male and female created he them.
    28 And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.
    29 And God said, Behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat.
    30 And to every beast of the earth, and to every fowl of the air, and to every thing that creepeth upon the earth, wherein there is life, I have given every green herb for meat: and it was so.
    31 And God saw every thing that he had made, and, behold, it was very good. And the evening and the morning were the sixth day.
    So are we reinventing the wheel
     
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  7. exchemist Valued Senior Member

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    Yeah, yeah, we've just had Easter so I'm up to speed with Genesis. What's your point?
     
  8. timojin Valued Senior Member

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    The period of high oxidation come when plant emerged . Do you really want to know my point ?
    Once the waters were removed into clouds and ice at the pols , the previous surface come back to live , because life was at the earth before. ( nothing to do with Noa flood )
     
  9. exchemist Valued Senior Member

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    No, it was when cyanobacteria emerged. That was about 2.3bn years ago, whereas plants emerged about 0.5bn years ago.
     
  10. timojin Valued Senior Member

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    Don't you think the gap is very large , yet the plant and cyanobacteria both are oxygen producers, Cyanobacteria of algae requires liquid environment , that implies the earth surface was wet. ( agreement with Genesis 1 )
    Following the OP. I believe the beginning of copper was patina or malachite in a dry surface a green color , because the lack of oxygen , CO2 moist environment would be (Cu2(OH)2CO3) As there would be an increase of oxygen the color would change to brown or black for cupric oxide .
     
  11. exchemist Valued Senior Member

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    Well of course the Earth was "wet". It was largely covered in ocean, just as it is now.
     
  12. timojin Valued Senior Member

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    Would you settle it could be more wet in the time of Pangea, Remember India collided , The Alpe mountain were formed and other mountain were formed . So it can be assumed water was spread more evenly then is now.
     
  13. exchemist Valued Senior Member

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    Well I think I have read that the blocks of continental crust seem to have got bigger over geological time, as a result of the fractionation processes involved in the generation, and then eruption, of magma. But I don't really know what you mean by water being more evenly spread. In the time of Pangaea, all the continental crust was in a single block, so at that time the water would have been less evenly distributed around the globe than today.
     
  14. timojin Valued Senior Member

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    I don't understand the crust got bigger, the crust is the layer over the magma , unless you are saying the earth sphere increased in diameter . The crust will go into subduction in places and elevation in other places .
    If you look at mountain formation by collision you will have a thicker crust and so the dry surface at the sea level will decrease
    I believe in the Pangaea time the land was more flat and marshe because did not have variety of elevation and Would think there was more algae on the surface as at the present.
     
  15. exchemist Valued Senior Member

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    Yes but the continental crust is lighter than the oceanic crust and floats higher as a result of its lower density. What I have read is that magma tends to be lighter fractions of the rocks that melt in the upper mantle/lower crust (which is one reason why they rise, thought they do also have dissolved gas). Over time, this process has tended to separate the minerals so that more of it forms these floating masses, at the expense, presumably, of the oceanic crust and mantle rocks becoming a bit denser. There's no change in the amount of rock obviously but you have more of it separated and riding higher above the rest. But I see from the following Wiki article that there are competing theories about this process and indeed whether it takes place at all: https://en.wikipedia.org/wiki/Continental_crust

    Interesting subject, actually.
     

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