Anonymous asked in Science & MathematicsEarth Sciences & Geology · 8 months ago

I don't quite understand how dead organisms became crude oil underground. How does that happen?

Based on what I read, very small sea creatures that lived in dinosaur era died and fell to the bottom on the sea bed.

Along with them lot of plants also died and fell to the sea floor.

Then after some 150 million years, they became crude oil. How? 

So that means buried humans will also become crude oil? 

5 Answers

  • Favourite answer

    The small sea creatures that became oil were mostly algae and other simple organisms that are typically found in sea water. Over millennia, as these organisms died and they sunk to the ocean floor their remains would accumulate, particularly if the water by the floor was oxygen poor.

    Over time great masses of the remains would accumulate and sometimes would be covered by thick layers of sediment. Sometimes the same thing would happen again and new layers of organic material would be formed. Over millions of years these layers could even become thousands of feet thick.

    The great weight of these layers, as well as heat from the earth's interior, caused chemical changes that resulted in the formation of petroleum.

    The same sort of thing happened with coal formation, except that it was the result of accumulation of the remains of early plants that were covered by sediment, again, repeatedly, over millions of years, so that coal is found in multiple layers, one on top of the other and separated by the sediments. These coal deposits are typically of plants that lived hundreds of millions of years ago.


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  • 8 months ago

    It is similar to how coal forms, but the physical and chemical changes are somewhat different when it comes to forming oil (plus the starting material is a bit different). The chemistry that is occurring as pressure and temperatures rise with increasing burial lead to formation of a mixture of grease, oils, waxes, liquids, and gases.  The plant material gets partially degraded after burial, and what remains is not exactly what was there to begin with.  The chemistry is extremely complicated (ask anyone how difficult they found the organic chemistry courses that they took), but it is just a matter of chemistry all the same.

    For the most part, it does not take tens of millions of years to happen, but the stuff does not disappear so we tend to find oil deposits in places that can be that old and older.  The more important thing is environment in the past rather than time. Regions of warm shallow seas tend to have very productive waters for life, and that much life sinks and gets buried in excess relative to many places, and that is why there is enough vegetative debris in sediments to allow significant amounts of oil to form.  Most of these places are not warm shallow seas today, but were shallow seas for long periods in the past.

    I realize that I have not actually defined the chemistry involved, but heck, to do that I would need many weeks of teaching, and even then it would not be complete.

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  • 8 months ago

    Well, it wasn't exactly like that. there was crude oil before dinos were around.

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  • CRR
    Lv 7
    8 months ago

    It needn't take millions of years. Dead animals can be converted to crude oil in a few hours in the laboratory. Even algae and sewerage can be converted to oil!

    It is more plausible that large quantities of organic material buried during Noah's Flood would provide an ideal base for production of crude oil with the great depth of sediment deposited providing the pressure.

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  • klypos
    Lv 6
    8 months ago

    What you are missing is that over millions of years a lot of sediments, sand and bits of sea creatures, fell on top of the organic stuft. There was tons and tons of sediment, and it exerted pressure on the organic matter - so much pressure that the organic stuff turned to oil and the sediments stuck together to form rocks.

    Yright, that is not very convincing, either, but pick at that point, where the pressure came from, and that is when the scientists get vague and evasive. They just say "you can see that the sedimentary rocks were formed, it took pressure to do that".

    Buried people could become oil if enough rocks is formed on top of them to give pressure, and if it did happen you would be dead before you could notice.

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