[RuGlu6]

Originally Posted by Stones

Speaking from a geological perspective, all of the oil reserves discovered so far have been formed from the decay of predominatly algae, bryozoans, and plankton in either a fresh water or marine environment.

The reason why such reservers are now situated at depths exceeding 22 000 feet is that all of the overlying rock is overburden. At one point in time, these organisms lived at the surface of the earth's crust in shallow lakes, inland seas, as well as the ocean. After they died and sank to the lake or sea bottom, these organisms were buried with sediments that over millions of years, accumulated to the true vertical thickness of rock we see overlying any given reserve of oil.

At one point in time, it was thought that oil could also have been generated from an igneous rock source through degration of certain minerals under extreme heat and pressure. This however, has never been proven as I've read several papers on the subject, all of which clearly state that oil has in all instances thus far, been generated from an organic source.

How about planets that never had organic life and yet have carbon based fuel ?