Possible Tectonic Impact of Biosphere
This paper explores the possibility of existence of ultra-deep biosphere (deeper than 10 km under the surface) and the biogenic earthquake hypothesis -- the idea that subsurface microorganisms might be directly related to earthquake activity. The importance of electroautotrophic type of metabolism is underlined, and the role of telluric currents in this process is explored in some detail, as well as the role of subsurface and atmospheric microorganisms in the global electric circuit.
It seems that the existing estimates of the adaptability of biological organisms are inconsistent with empirical evidence, and theoretical concepts predict key biochemical processes to fail long before the onset of the temperatures and pressures, at which microorganisms are actually observed. This implies that life might exist much deeper beneath the surface than previously assumed. At the same time the estimates of energy radiated during the strongest earthquakes are consistent with the biochemical energy available to the subsurface biosphere.
Some additional evidence is examined. It is proposed that the ultra-deep biosphere might represent an important factor in resolving the debate on the nature of hydrocarbons. At the same time the deep subsurface microorganisms might play a significant evolutionary role, not only providing seismically induced genetic variation and a "seed bank" for quick recovery after a mass extinction, but also by modulating longer climatic cycles through planetary-wide bio-geo-electrochemistry.