Michael, thanks for the Thomas Gold article. Since oil is a hot topic and dominates foreign affairs in Iraq, herewith my rant.
Way back in 1983, I noticed that ophiolites [the earth's crust flipped up onto the surface during tectonic subduction activity] and oil were close to each other around the world.
I'd accepted the idea that oil formed in sedimentary marine layers and the organic material turned to oil, being cooked in hotter and deeper layers, then floated up to be caught in traps or leaked to the surface.
I realized that the mechanism for oil formation is fish, whales and micro bugs in the oceans sinking to the bottom, being collected in radiolarian ooze, buried in marine sediment, then carried on the crust like a conveyor belt as it gets pushed along by earth's internal molten circulation currents. to be finally subducted at the tectonic plate boundaries.
As the crust and sediment plunge down [slowly, at 10cm per year or thereabouts, depending on the subduction zone], the sedimentary stuff is subjected to increasing pressures and temperatures.
In marine deposits, there's water, bone, dirt from the atmosphere and river runoff, oil [marine beasties contain oil] and other organic stuff left over from the marine beasties. That's a good feedstock for some chemistry at high temperatures and enormous pressures.
Being cooked, freed from it's sedimentary pore prisons, and lighter than the surrounding minerals, it floats up. Some of it gets into volcanoes and provides some bang, fire, smoke, CO2 and other whoopie when volcanoes let rip. As the column of volatile liquids in a magma chamber and the eruption zone leading to the surface turns to gas as the pressure is released, there is enormous propulsion upward.
Not all the oil goes up in smoke out of volcanoes. Some trickles more quietly upward through pores as described by Thomas Gold, finally being caught in sedimentary traps to await rescue by petroleum miners. I guess that some of it goes through zeolite clays, which do some reformation of the molecules [similar to the chemical processes used to produce synthetic gasoline using Mobil's Syngas process].
There are many hydrocarbons formed, from methane down to heavy bitumens. Cracking and polymerisation and zeoliting and enormous pressures and high temperatures can do a lot and there's a long time for it to happen.
I got quite excited when figuring this out because I thought I might be able to point to exact locations for oil to be found, or at least high prospectivity areas. I was going to be richer than Getty and Rockefeller combined. But I gave up as trap-finding was still the key and oil prospecting was largely where my beloved ophiolites are anyway.
Such a large scale oil production and collection system explains why giant puddles form in certain areas. Such as Saudi Arabia and that area. A trap sitting at the end of such a conveyor system could collect oil from subduction for millions of years. At 10cm per year subduction rate, that's a lot of subducted marine sedimentary material going somewhere.
It also explains the oil and gas in Thomas Gold's Swedish granite 6 kilometres down. The type of oil formed can be light waxy watery looking condensates, such as in Taranaki, with lots of methane, propane, butane etc, or heavy sulphurous glutinous bituminous crudes such as Venezuela's Orimulsion [BP's water/oil emulsion made from Venezuela's heavy crude] and Canada's tars.
The marine sediments fed into the subduction zone, the depth of subduction, speed, rate of separation of liquids from subduction zones etc will determine what sort of hydrocarbons are formed. I suppose the light stuff results from a quick cook and the heavy bituminous stuff results from a long and hot cook with light stuff being polymerized.
That's my half-baked theory anyway.
I doubt that reservoirs are refilling fast enough to keep us in oil. But anyway, there's so much of it, if the heavy crudes are included, that there's enough to last until the human population has dwindled to 1 billion by 2100. By which time oil will be as interesting as flint from the stone age. It'll never run out. As Sheik Yamani said, the oil age won't end for want of oil, just as the stone age didn't end because of a stone shortage.
Mqurice
PS: It seems obvious that Gold was right that the moon is covered in thick dust. A frozen rocky moon, constantly pummelled by incoming strikes [as shown by craters everywhere], will result in dust flying. As shown by the footprints of the astronauts, the surface is in fact covered in dust and it's sure to be more than skin deep because those craters are everywhere and they dig down quite a way. Of course there'd be rocks too, as they'd not all be broken to smithereens and so it turned out to be - plenty of moon rocks were brought back. |
