[extropy-chat] Deep-earth methane generation

[Mike Lorrey]

--- Hal Finney <hal at finney.org> wrote:
 
> This would seem to contradict at least two of Mike's claims.  The
> Gulf
> floor is apparently only about 150 million years old, younger than
> many dinosaurs; and it was indeed above water at least intermittently
> during the time when the salt formations were created.  There are
> also
> apparently many sedimentary layers present. It's also worth noting
> that oil is thought to be formed by aquatic life, such as algae, not
> dinosaurs.

I'll note that he states that the salt domes are 3 km under the floor
before pressure rises enough to produce oil. Yet the ocean floors are
only thought to be 5-10 km thick, which creates a paradox. If the upper
3 km that covers the salt domes was produced over 60 million years, and
the floor is 150 million years old, then the sedimentary layer of the
gulf should be about 7.5 km thick, thus the basalt at the spreading
zones can be at most 2.5 km or less thick, which we know isn't true
because of the amount of material put out by the spreading ridges. But
we'll let that aside for a bit.

Now, lets look at the amount of sediment: 7.5 km thick. How much is
biological material? Dunno, but it is all subducted under the
continents at some point, silt, methane hydrates, oil, salt domes,
rock, and all. Does all that oil and methane hydrates just disappear?
Obviously not. Is there air for the oil and methane to react with to
burn into carbon dioxide and water? No, there isn't.

How much subduction happens? How many tons of stuff gets subducted
every year? While some deep sediments in the ocean floor may be covered
deep enough to turn to oil in situ, it is clear that, given what we
know about methane hydrates, there is a LOT more of this stuff,
unconverted, waiting to be subducted, and being subducted, all the
time.

Lets make a pessimistic guesstimate that there is about 100,000 km of
subduction zone sucking oceanic sediment under. And lets say there is
an average of 7.5 km of sediment at any given point getting subducted.
Given an average subduction rate of 3 cm/year, that means 22.5 cubic km
of material being subducted worldwide every year. (suck, suck, suck)

If we were to assume, say, that a mere 1% of the material in subducted
ocean sediment is suitable for conversion into oil at appropriate
pressure and temperature, this means that the earth produces .225 cubic
km of oil every year, for every 1% of convertible subducted ocean
sediment. How that converts to barrels d'huile is an exercise left for
the reader.

Now, the only reason geologists have claimed that oil comes from
aquatic algae is because of fossilized cellular structures found in
oil, which has been assumed until recently to be the 'algae' that
'made' the oil. This was before the discovery of hyperthermophiles and
oil eating bacteria, both of which live deep underground and thrive off
of chemosythnesis rather than photosynthesis.

The excuse making I hear now is that a) the Gulf, which is up to 2000
fathoms deep in places, repeatedly dried up entirely when it was cut
off from the ocean at various points, and that b) while exhibiting such
immense saline concentrations, was home to an immense amount of algal
blooms, apparently c) the entire gulf being fed by an occasional flash
flood down the Mississippi.

Mike Lorrey
Vice-Chair, 2nd District, Libertarian Party of NH
"Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves."
                                      -William Pitt (1759-1806) 
Blog: http://intlib.blogspot.com

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