permaculture

[Marimike6@cs.com]

The abiogenesis of oil, coal and natural gas deposits is an idea that a 
majority of petroleum geologists and engineers put into the same category as 
Hollow 
Earth Theory, or the extraterrestrial origin of life. 

Not surprisingly, a great many of our sharper minds have been employed for a 
very long time determining the nature of fossil fuel deposits, as a guide 
toward exploration. There are a few people, even respected scientists, who 
differ-- but their arguments tend toward the theoretical and abstruse. They 
don't 
have the advantage of having much unequivocal evidence to back them up.

Fossil fuel deposits, as a general rule, are found to occur in synclines 
where ancient bodies of water have allowed the accumulation of vast 
quantities of 
dead organic matter without dispersal. Most of this matter tends to be algae, 
which in its rotted, chemically stable form is known as kerogen.  It is then 
pressure cooked over long periods of time-- and heat, pressure and time all 
play a part in the nature of the deposits created. These processes are known 
as 
thermal degradation and cracking.

Generally speaking, petroleum deposits that have cooked for too long end up 
as short-chain hydrocarbons, or natural gas (methane, ethane, hexane, etc.). 
Don't cook them long enough, or under enough pressure and they appear as oil 
shales, coal-tar, tar sands and so-called "heavy oil". These substances, 
stiffer 
and more viscous, are composed of long-chain hydrocarbons. They are less 
volatile, i.e. harder to burn, and make good asphalt.

The principle problem with the deep-earth origins of such substances is that 
deeper than (as I recall) about 15,000 feet, pressure and temperature are so 
great as to fry the oil. All the long-chain hydrocarbons get rendered into 
the 
lighter gases. Any explanation involving origin in the mantle would need to 
explain how these volatiles, when trapped in sediments closer to the surface, 
are able to convert themselves into longer hydrocarbon chains.

Theoretically it is certainly possible to have natural gas pockets appear 
from mantle events. But no convincing evidence of which I'm aware has been 
put 
forth to illustrate that many or most of the deposits we've examined are from 
such a source. 

A good general introduction to the fossil fuel formation debate can be found 
here:

http://www.aapg.org/explorer/2002/11nov/abiogenic.cfm 

A caveat: I'm not an expert. Anyone with something more accurate to say, 
please jump on in.

Michael