Although the claim for a substantial abiogenic component to fossil fuels
does not seem to hold up (as other posts have discussed), there is some
recent support for the origin of life at high temperature such as a
hydrothermal vent setting. Usually this is envisioned as a seafloor vent,
but I would think a hydrothermal setting deep in the earth's crust would do
just as well. There are two lines of evidence I know of. Some recent
experiments have been able to create biologically important molecules under
hot vent-like conditions, although important gaps remain. Secondly, some
of the thermophyllic bacteria are also very primitive, and their position
on some phylogenetic analyses is compatible with the ancestor of all modern
organisms also being thermophyllic. Other phylogenetic analyses disagree.
Also, there are some relatively credible recent reports of bacteria living
deep in the earth's crust, although contamination is difficult to disprove.