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Thread: Origin of oxygen in earth's atmosphere

  1. #1 Origin of oxygen in earth's atmosphere 
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    ORIGIN OF OXYGEN IN EARTH’S ATMOSPHERE
    By Suhail Jalbout

    Most scientists agree that there was no free oxygen in the atmosphere of early Earth. However, some scientists claim that the original atmosphere of the Earth was composed from methane, ammonia, hydrogen, and water because this mixture of molecules is present in interstellar space. Other scientists believe that as Earth began to develop a solid crust about 4 billion years ago, gases from volcanic eruptions formed an atmosphere with a composition similar to the present emanations from volcanoes. If we assume that both theories are correct, then the early atmosphere of the Earth consisted of: water (H2O), carbon dioxide (CO2), methane (CH4), ammonia (NH3), hydrogen (H2), nitrogen (N2), and other small amounts of miscellaneous gases.

    It seems that free oxygen was produced on the Earth around 2.5 billion years ago. It was generated by photosynthesizing organisms known as cyanobacteria or blue-green algae. These tiny organisms conduct photosynthesis by using ordinary sunlight, water, and carbon dioxide to produce carbohydrates and oxygen. Since these organisms lived in oceans, the produced oxygen molecules bubbled up from the oceans into the atmosphere. The presence of oxygen changed the composition of the early atmosphere into the present oxidizing atmosphere which consists of: nitrogen (N2 -78%), oxygen (O2– 21%), and other gases such as water and carbon dioxide.

    The first living forms on Earth appeared around 3.5 billion years ago. Since free oxygen was generated about 2.5 billion years ago, this means living organisms on the Earth were exposed to ultraviolet light for 1 billion years. Ozone did not exist during this period to form a protective shield. Consequently, it is very difficult to explain how primitive life developed and evolved into complex organisms in the presence of UV.

    I believe oxygen was produced on the Earth about 3.5 billion years ago. Sometimes around this date, Earth experienced the following important changes:
    1. Oceans were formed on the surface
    2. Single-cell organisms appeared for the first time
    3. Ozone layer was formed in the upper atmosphere
    In my hypothesis “Origin of Water on Earth” I have reached a conclusion that oceans were created on the Earth from the collapsed water-ice ring that was in its orbit. Water in huge amounts flooded the Earth and created oceans during a short period of time.[1]

    In my hypothesis “Origin of Life on Earth (Parts I and 2)” I have concluded that the creation of single-cell organisms during the formation of stars is 157 million times more probable than their creation on Earth- like planets, a pessimistic estimate.[2] Consequently, the water-ice ring that was orbiting the Earth must have harbored single-cell organisms in a frozen state. When the ring collapsed, it created oceans and populated the Earth with life about 3.5 billion years ago.

    When the ring entered the early atmosphere of the Earth, a large percentage of its water-ice evaporated due to friction. Since the ring contained about 1.33x10^18 tons of water, the atmosphere became completely saturated with water vapor extending from the surface of the Earth to very high levels in the atmosphere. Water molecules and dust particles from volcanic eruptions formed enormous electrically charged clouds around the Earth. As a result, lightening with immense intensity dominated the skies all over the world. These new conditions paved the way for the production of oxygen by the following two methods:

    PHOTOCHEMICAL DISSOCIATION

    Water molecules, at the upper levels of the atmosphere, were broken up by ultraviolet light into hydrogen and oxygen atoms. Two oxygen atoms combined to form an oxygen molecule and a third oxygen atom combined with an oxygen molecule to form ozone. This means an ozone layer was formed in the upper levels of the atmosphere shielding the ultraviolet light and reducing its harmful effects.

    ELECTROLYTIC OXYGEN AND OZONE GENERATION

    The formed highly charged clouds and the surface of the Earth acted as a gigantic electrolytic oxygen and ozone generator. The discharge of electrons, during lightening, between the charged clouds and Earth’s surface dissociated water molecules and produced hydrogen, oxygen, and ozone. It is to be noted that ozone is created in nature by lightening and can be smelled after a storm. The newly formed ozone ascended to the upper levels of the atmosphere and joined in the formation of the ozone shield. While the newly formed free oxygen combined with the gases of the early atmosphere to form an intermediate atmosphere about 3.5 billion years ago. For example:
    1. Oxygen combined with methane to produce carbon dioxide and water: (CH4 + 2O2 = CO2 + 2H2O)
    2. Oxygen combined with ammonia to produce nitrogen and water: (4NH3 + 3O2 = 2N2 + 6H2O)
    3. Hydrogen combined with oxygen to form water: (2H2 + O2 = 2H2O)
    The newly formed intermediate atmosphere consisted mainly of: nitrogen, carbon dioxide, hydrogen, and water with very small amount of oxygen. Most of the oxygen that was generated formed the ozone layer and combined with the gases of the early atmosphere.

    In conclusion, the intermediate atmosphere and the ozone shield provided favorable conditions for simple primitive life forms to grow and develop into very complex organisms. Some of these complex organisms produced free oxygen which increased the amount of oxygen in the atmosphere to 21% forming our present atmosphere.

    END NOTES
    [1] www.thescienceforum.com/.../22663-origin-water-earth.html
    [1] 2012 Forum • ORIGIN OF WATER ON EARTH
    [2] www.thescienceforum.com/.../23461-origin-life-earth-4.html
    [2] 2012 Forum • ORIGIN OF WATER ON EARTH
    [2] 2012 Forum • ORIGIN OF LIFE ON EARTH (PART 2)
    [2] ORIGIN OF LIFE ON EARTH


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  3. #2  
    Time Lord Paleoichneum's Avatar
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    I got to ice ring, and stopped, everything after that is bollocks


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    Quote Originally Posted by Paleoichneum View Post
    I got to ice ring, and stopped, everything after that is bollocks

    That seems harsh, must have taken him ages to type all that.
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  5. #4  
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    Uhhh, that was clearly a copy and paste. And since it is BS, I did the same thing, but made it a sentence or two further for fun.
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  6. #5  
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    Quote Originally Posted by Chrisgorlitz View Post
    That seems harsh, must have taken him ages to type all that.
    I don't see the relevance. Nonsense is nonsense no matter how long someone spends on it. Maybe he should post in a science fiction forum - might get a more positive response.
    ei incumbit probatio qui dicit, non qui negat
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    I still hate the fact that you kinda burn, but don't try to correct him.

    The early atmosphere probably did not contain hydrogen, it's not stable enough. Let's say the earth contained gasses like N2, SO4, H2SO2, CO2, NH3 (maybe), and Ar, He, Kr etc.

    Was not sure about the NH3 because it seems like a bound nitrogen particle. Hmm.
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  8. #7  
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    Quote Originally Posted by Zwolver View Post
    I still hate the fact that you kinda burn, but don't try to correct him.
    He has posted exactly the same thing multiple times and ignored any attempts at explanation. The standard explanations (based on evidence, etc) are, according to him, just not "plausible" (based purely on ignorance and incredulity as far as I can tell). He usually gives up the argument after a few posts. And then posts the same nonsense again a bit later (hoping to con some new gullible fools, perhaps).
    ei incumbit probatio qui dicit, non qui negat
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  9. #8  
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    Harsh but fair, its pretty hard to argue with 'nonsense is nonsense'.
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  10. #9  
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    Hmm, oke. Still sounds like to much trouble for someone just to do to make "fools" believe this stuff..
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
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  11. #10  
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    Quote Originally Posted by Zwolver View Post
    Hmm, oke. Still sounds like to much trouble for someone just to do to make "fools" believe this stuff..
    You must be new here

    There are many, many people who have dedicated decades to developing their personal wacky theories based on their limited understanding of popular science and the application of "common sense".

    They love to promote their ideas on forums like this. They claim they are ignored because of "dogma", "fear", "conspiracy", "cover up", "big oil" etc. The frequently compare themselves to Einstein or Galileo. Their website are usually as well ordered as their thoughts (i.e. not very) and utilise a large number of garish colours and fonts in a remarkable range of sizes.

    If they had spent as much time actually studying physics first and then come up with a novel theory, they might have got somewhere.

    This brief introduction to the lesser-spotted crackpot was brought to you by the Secret Committee of Dogmatic and Terrified Scientists.

    Actually, I guess the OP in this case may have a religious motivation. But that is not something I know a lot about.
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    ei incumbit probatio qui dicit, non qui negat
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  12. #11  
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    Yep, this poster is very much advocating for a literal interpretation of the Koran's creation stories
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

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    It seems oxygen existed in Earth’s atmosphere 3.46 billion years ago.[1]
    “ recent research, just published in Nature Geoscience , suggests that oxygen was present in the atmosphere as early as 3.46 billion years ago. This latest research was jointly supported by the NASA Astrobiology Institute, Kagoshima University, University of Tokyo and the Department of Geosciences, and the Pennslvania State University. Masamichi Hoashi and his co-workers looked at the hematite-rich chert (chert is a brittle sedimentary rock) obtained from the deep drill core in the Pilbara Craton of Western Australia. Hematite is produced through oxidation process, so dating ancient sources of hematite can be used to discover when oxygen was present on Earth.”[2]
    [1] www.eurekalert.org/pub_releases/2009-03 ... 032409.php
    [2]www.rockcollector.co.uk/editorial0409.htm
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  14. #13  
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    Quote Originally Posted by Suhail Jalbout View Post
    It seems oxygen existed in Earth’s atmosphere 3.46 billion years ago.[1]
    “ recent research, just published in Nature Geoscience , suggests that oxygen was present in the atmosphere as early as 3.46 billion years ago. This latest research was jointly supported by the NASA Astrobiology Institute, Kagoshima University, University of Tokyo and the Department of Geosciences, and the Pennslvania State University. Masamichi Hoashi and his co-workers looked at the hematite-rich chert (chert is a brittle sedimentary rock) obtained from the deep drill core in the Pilbara Craton of Western Australia. Hematite is produced through oxidation process, so dating ancient sources of hematite can be used to discover when oxygen was present on Earth.”[2]
    [1] www.eurekalert.org/pub_releases/2009-03 ... 032409.php
    [2]www.rockcollector.co.uk/editorial0409.htm
    your point being?
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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    @Suhail Jahout

    1. Your argument for the need for oxygen to be present on the early Earth is that " living organisms on the Earth were exposed to ultraviolet light for 1 billion years. Ozone did not exist during this period to form a protective shield. Consequently, it is very difficult to explain how primitive life developed and evolved into complex organisms in the presence of UV."

    However, there is no need for the organisms to live on the Earth. UV is readily absorbed by water, or by rock, the location where these organisms would flourish.

    Secondly, complex organisms (eukaryotes and multicellular life) evolved after 2 bya, once the ozone layer had been established.

    So, there is no need to search for an explanation for the presence of an early oxygen rich atmosphere.

    2. The possible presence of oxygen in the early atmosphere was known to me and I intended to correct your initial assertion that scientists think the early atmosphere was wholly oxygen free. The source you quote is not the first to explore this possibility.

    3. You offer no evidence for the source of the ice ring, nor a reason it should become unstable and collapse onto the Earth.

    4. You postulate a pan spermia solution for the origin of life. Why did the Stardust mission fail to find any evidence of life in cometary ices?
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    I wish to thank you for giving me the opportunity to comment on your points as follows:
    1. I did not search for an explanation for the presence of an early rich oxygen atmosphere to explain how primitive life evolved into complex organisms. The latter came as a by-product for the existence of an ozone shield about 3.5 bya. The hypothesis that primitive life played “hide and seek” with UV for 1 billion years in oceans is no more valid. The existence of oxygen in earth’s atmosphere formed an ozone shield about 3.5 bya. This means the ozone shield and the intermediate atmosphere provided favorable conditions for primitive life forms to live anywhere they can find food on our planet and thus evolve into complex organisms.
    2. There is no evidence that oxygen existed in the early atmosphere before 3.5 bya. If it did, then the laboratory results of Stanley Miller and Harold Urey experiment would be different. If the multi-cellular life forms that produced oxygen evolved only about 2.5 bya, then from where oxygen appeared in earth’s atmosphere about 3.5 bya? I find the answer in the OP.
    3. a. The D/H ratio of our oceanic waters suggest that the origin of the major part of our water came from the same source, the water-ice ring, because the measurements of the isotope ratios of hydrogen in the three comets Halley, Hale-Bopp, and Hyakutake were double that of our oceanic water.
    b. The gravitational force between the moon and earth about 4.5 bya was almost 9 times the present. The moon was pulling part of the water-ice ring away from earth thus causing it to expand while the combined gravitational effects of both the moon and earth were pulling the other expanded part of the ring towards earth.Just before the formation of oceans on our plant, the gravitational force of the moon was reduced by 50% and had no more effects on the ring. Due to this reduction, the gravitation of earth shrank the ring thus increasing its concentration and mass causing it to change its angular momentum leading to its collapse
    4. I am confident that other missions will find life in the near future.
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    The PHOTOCHEMICAL DISSOCIATION HYPOTHESIS is: [1]

    “Ozone is produced in the upper atmosphere through photochemical reactions involving
    UV radiation and water:

    2H2O + uv radiation = 2H2 + O2
    And
    2O2 + uv radiation = O3 + O
    And
    O + O2 = O3”

    If we assume that the photochemical dissociation hypothesis is wrong and the writer’s “knowledge of basic physical chemistry is so wrong”, then oxygen and ozone were generated by the 2nd method, “ELECTROLYTIC OXYGEN AND OZONE GENERATION”, which is not debatable.

    [1] www.usouthal.edu/geology/haywick/GY112/112lect19.pdf
    [2] www.ux1.eiu.edu/~cfjps/1400/atmos_origin.html
    [3] www.britannica.com/EBchecked/topic/457809/photodissociation

    [4] www.nisdtx.org/cms/.../Ozone%20Oxygen%20and%20Tectonics.ppt
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    There were trace amounts of Oxygen bound in water molecules, and Carbon dioxide…but none of it ... Photochemical Dissociation Hypothesis states that the sun's energy helped the ... 2H2O + uv light energy ----> 2H2 (freed into space) + O2 ...
    [5] rockbox.rutgers.edu/~jdwright/Historical/02_Origins.pdf
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    b. Photochemical dissociation i. dissociation of water molecules into hydrogen and oxygen: 2H2O + uv radiation —> 2H2 + O2 ii. occurs in the upper atmosphere ...
    [6] quizlet.com/13998519/2c-earth-modern-atmosphere-flash-cards/Cached
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    Sep 18, 2012 – Photochemical Reactions, ␣ 1. Dissociation of water vapor to hydrogen and oxygen with hydrogen escaping into space: - 2H2O+uv light = 2H2 ...
    [7] www.uh.edu/~geos6g/1330/solarsys.html
    [8] www.umich.edu/~gs265/spheres.htm
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    Cyanobacteria was the first photosynthesizer, and thus the first producer of oxygen (Eden, 33 and Wolfe, 143).

    Cyanobacteria itself cannot be the cause for the accumulation though because according to current theories and history models cyanobacteria appeared almost a billion years before the oxygen accumulated in earth’s atmosphere.Details
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  19. #18  
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    Quote Originally Posted by Some View Post
    Cyanobacteria was the first photosynthesizer, and thus the first producer of oxygen (Eden, 33 and Wolfe, 143).

    Cyanobacteria itself cannot be the cause for the accumulation though because according to current theories and history models cyanobacteria appeared almost a billion years before the oxygen accumulated in earth’s atmosphere.Details
    Another creationist website. About Me! | Matthew2262's Blog *Sigh.*
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    Quote Originally Posted by Some View Post
    Cyanobacteria was the first photosynthesizer, and thus the first producer of oxygen (Eden, 33 and Wolfe, 143).

    Cyanobacteria itself cannot be the cause for the accumulation though because according to current theories and history models cyanobacteria appeared almost a billion years before the oxygen accumulated in earth’s atmosphere.Details
    Well at least you're in the pseudoscience forum--where religious garbage wrapped in "science speak" can dupe the ignorant while completely ignoring the strong evidence for huge deposits of marine oxide deposits that happened about the same time as the first cyanobacteria evolution.
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    We do not need cyanobacteria to photosynthesize to form oxygen. The reaction which everyone seems to have missed is between H2O and UV light in the upper atmosphere to form H2O2 (hydrogen peroxide). This is formed very rapidly and a good proportion then decomposes rapidly to generate O2. Here are the overall equations (there are a good number of intermediate steps but they are all fast) in the presence of UV radiation:

    2H2O => H2O2 + H2 (the hydrogen escapes and is largely lost to space)
    H2O2 => O2 + H2 (the hydrogen escapes and is lost to space)

    Some of the peroxide reaches the ground. Even today hydrogen peroxide is present in rain to a greater or lesser extent. When it reaches the ground it will catalytically decompose to oxygen and water, viz.

    2H2O2 => O2 + 2H2O

    Lots of solids are catalysts for this reaction, including ferric oxide / rust.
    So all you need is water and UV in the high atmosphere and oxygen will gradually accumulate. Simple.

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    Quote Originally Posted by Suhail Jalbout View Post
    The gravitational force between the moon and earth about 4.5 bya was almost 9 times the present. The moon was pulling part of the water-ice ring away from earth thus causing it to expand while the combined gravitational effects of both the moon and earth were pulling the other expanded part of the ring towards earth.
    In other words - the ice ring would have been unstable and thus never formed to begin with.

    Just before the formation of oceans on our plant, the gravitational force of the moon was reduced by 50% and had no more effects on the ring.
    Did someone abscond with half its mass? Quite a heist!

    Due to this reduction, the gravitation of earth shrank the ring thus increasing its concentration and mass causing it to change its angular momentum leading to its collapse
    "Increasing its mass?" Did said thief move the Moon's mass into Earth orbit and then change it to water? I'd like to know more about this thief.
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    Forget a water-ice ring. Heat from the Sun would cause the ice to rapidly sublimate and the water vapour would be driven away by the solar wind.

    Cometary scientists are now recognising that comets delivered a large proportion of water to the early Earth. Once the Earth had cooled sufficiently, much of the water, and many of the other volatile constituents of the cometary nuclei, were retained by the Earth's gravity. We see large amount sof water in other planetary systems at an early stage in their formation circling some other stars.
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    I first checked his references. When I realized he was referencing himself in other forum posts, I stopped reading. Is it at least funny?
    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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    Quote Originally Posted by Astromiles View Post
    So all you need is water and UV in the high atmosphere and oxygen will gradually accumulate. Simple.[/SIZE]
    Except other reactions will make the oxygen disappear - it's very reactive, you know.
    ei incumbit probatio qui dicit, non qui negat
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    Quote Originally Posted by Flick Montana View Post
    I first checked his references. When I realized he was referencing himself in other forum posts, I stopped reading. Is it at least funny?
    The fact that the parser has included &bull in some of his references is mildly amusing.
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  27. #26  
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by Astromiles View Post
    So all you need is water and UV in the high atmosphere and oxygen will gradually accumulate. Simple.[/SIZE]
    Except other reactions will make the oxygen disappear - it's very reactive, you know.
    Without doing the calculation (I'd have to look up photolysis rates and the rate constants for all the potential loss processes and it's midnight here and I can't be bothered) my gut feeling (as an atmospheric chemist) is that the steady-state oxygen concentration from this process would be very low. (As you say it would react with something else almost as quickly as it was formed). This paper seems to back up my gut feeling putting a limit of about 0.02% (they quote ~0.001 present atmsopheric level).
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    And the fact that there wasn't a significant amount of oxygen until after photosynthesis ...
    ei incumbit probatio qui dicit, non qui negat
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    That too...
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    Quote Originally Posted by Paleoichneum View Post
    I got to ice ring, and stopped, everything after that is bollocks
    I didnt even make it that far. I only got to "Most scientists agree that there was no free oxygen in the atmosphere of early Earth." before i said meh.
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    The crux of our kneejerk response to Suhail Jalbout's speculation is over the icy ring proposed. Ours is a position of incredulity. It's hard to imagine conditions of and around the early Earth being radically different than at present.

    I'll admit an icy ring plausible. A residue of one such ring orbits Saturn. These could have been much denser and more common before larger bodies had fully consolidated (before and during late heavy bombardment). The advancing frost line is pertinent here. Because a planetary ring beyond the frost line may contain accreted chunks of ice, while a (watery) ring within the Sun's range is volatile, and more like a diffusing nebula. Apparently our young Earth within the frost line couldn't support a ring of ice, let alone water.

    But let's creep onto thin ice, with the understanding that our young Sun's output was less than at present. The frost line must have, at some time, fallen short of Earth's orbit. An icy ring would be possible, then, maybe even probable. Does anybody know exactly when solar output, moderated by the solar disc "atmosphere" of planetesimals radiating and re-radiating heat, placed the frost line directly over Earth's orbit? At that moment, a ring composed of orbiting ice chunks must undergo a weird transformation. It would boil and diffuse under sunlight, but conversely condense (re-accrete) in the Earth's shadow. Shouldn't that greatly accelerate accretion? This scenario answers the ice ring collapse portion of Suhail Jalbout's hypothesis.
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    Quote Originally Posted by Pong View Post
    The crux of our kneejerk response to Suhail Jalbout's speculation is over the icy ring proposed. Ours is a position of incredulity. It's hard to imagine conditions of and around the early Earth being radically different than at present..
    It is because it's really out of whack with current hypothesis on early solar system output. Most models put solar output at about 70% of current output during the first billion years or so. That's only enough of a difference to move the frostline in by about 11% or so. Given the frost line is currently about ~2.6 AU, and even being generous it was probably >2 AU during the early solar system--that pretty much rules out an Earth orbiting ice belt.
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    There is this BIF - Banded Iron Formation phenomen. This basicially claims that the forming of the iron(III) ores eventually stopped around 1 billion years ago. If you think about this, it implies two things:

    1) There was a lot of iron(II), or iron(0) before that, and a negligible amount after that
    2) The iron(II) got oxidized somehow

    Now, what am I saying right here?

    Earth's crust was mostly made out of reduced compounds in the beginning. The atmosphere had a lot of reduced gases (like CH4, which I assume you also accept).
    Then, there came cyanobacteria, starting to produce oxygen. And what happened is that in the first 1-2 billion years, the oxygen in the atmosphere got absorbed by the reduced crust of Earth. This went on until all the iron(II) and similar contents got oxidized to a stable form. After that, oxygen levels could rise in the atmosphere.

    What do you say to prove BIR wrong?
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  34. #33 Origin of oxygen in earth's atmosphere 
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    @ Pong & Lynx_Fox (FROST LINE)Until recently, mathematical theories and computer simulations about our solar system were based only on our existing model. However, few of these theories were modified and others are under re-evaluation as a result of the discovery of all kinds of solar systems in space where giant exoplanets are orbiting at a close proximity to their parent star. There is still uncertainty about the behavior of the frost line during the evolution of our solar system. One probable theory on protoplanetary disk indicates that the frost line should migrate inwards as the viscous dissipation decreases with time which causes the accretion rate to drop and the disk to cool. Due to these conditions, the frost line can reach a distance well within the Earth’s orbit. However, the frost line migrates outwards again as the temperature increases once the disk becomes optically thin.Based on this analysis, it is quite possible that both Earth and Mars had small amounts of water in their orbits (water-ice rings and chunks of ice) as compared to the huge amount of water in our solar system.
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  35. #34  
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    BUT there is absolutely no geologic evidence of any sort of water bombardment at any point.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

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  36. #35  
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    Quote Originally Posted by Paleoichneum View Post
    BUT there is absolutely no geologic evidence of any sort of water bombardment at any point.
    How would you look for such evidence?
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  37. #36  
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    Ancient rock/terrain which show formation without major hydrology influence followed by sudden massive hydrology for starters.
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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  38. #37  
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    OK
    It seems that the oldest known rocks(forgetting zircons for the moment) are greenstone.
    Which form in oceans.
    which puts oceans at 3-8 to 4.28 billion years ago
    (from ophiolite/Galt?)
    Accurate?
    Last edited by sculptor; April 5th, 2014 at 05:19 PM.
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  39. #38  
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    Quote Originally Posted by sculptor View Post
    OK
    It seems that the oldest known rocks(forgetting zircons for the moment) are greenstone.
    Zircons are not rocks; they are minerals.
    The oldest known rock, with a confirmed age, is a gneiss, not a greenstone.

    Quote Originally Posted by sculptor View Post
    Which form in oceans.
    No they don't. They are a complex mix of metamorphosed sedimentary and volcanic rocks.

    Quote Originally Posted by sculptor View Post
    which puts oceans at 3-8 to 4.28 billion years ago
    (from ophiolite/Galt?)
    Good age for the oceans, but not on the basis of the presented 'facts'.
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  40. #39  
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    Taking me to school again ophiolite
    (I had thought that the greenstones were gneisses)
    oops
    Thank You sir.
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