About eight years too late, I finally got around to reading Deep Hot Biosphere by the late Thomas Gold. This controversial book expounded Gold's theories that petroleum and natural gas are not formed from biological sources. Instead, he argued that petroleum, natural gas, and even (non-anthracite) coals were formed from geologic, not biologic, processes.
The title of the book comes from Gold's attempt to explain the presence of molecular "fingerprints" of once-living organisms in petroluem, for example, the carbon skeletons of cholesterols and other lipids have been found in oil. The traditional theory says these molecular traces are simply evidence of the once-living organic matter from which petroleum was eventually formed. Gold, however, rectified his abiogenic theory with these molecular tracers by positing the widespread existence and activity of microorganisms deep in the earth, in the pores of metamorphic and igneous rocks. Why stop there? He then went on to argue that the deep hot biosphere is a more likely spot for the origin of life than the primordial pool we're always hearing about.
Sound pretty far fetched? It did to me too. But, I'm an industrial microbiologist by training, so I was intrigued by the possibility of deep subterranean bacteria. Plus, the energy implications of Gold's theory are huge. If oil's not formed from fossils, it's not a fossil fuel! So I thought it was worth checking out.
I didn't take Gold's word at face value. First I went hunting for criticims of Gold's views out there in the blogosphere. Perhaps unsurprisingly, I found a lot of noise and vitriol but not too much cool-headed explications of modern geological understanding. Wikipedia, as usual, was marginally useful for background, it was too hard to get a reliable survey of modern geochemistry from Wikipedia alone. So in the end I relied on an introductory textbook in organic geochemistry as a Moriarty to Gold's Holmes.
In the next couple of posts, I want to discuss what, to my non-geologist layman eyes, look like key points of evidence for and against Gold's theory. Hopefully the knowledgeable will drop by to correct me if I mess up the planet science too bad. First up, I'll deal with the most arcane, difficult to explain data: stable isotope fractionation. Stay tuned!