Biogeology: A deep subject

Way down deep, below the lowest depths of the oceans, below the floor of the seas – in the rock of the ocean crust – there exists a world with life. It’s been known for some time that bacteria can live in rock. According to the research done by Martin Fisk and colleagues at the College of Oceanic and Atmospheric Sciences at Oregon State University (Corvallis, USA), and published in online journal PLoS One [ First Investigation of the Microbiology of the Deepest Layer of Ocean Crust ], the ocean crust has ecosystems of bacteria munching away at embedded hydrocarbons (oil, natural gas) – ecosystems.

The oceanic crust is 70 percent of the Earth’s surface, yet it’s never been explored for biology. That’s because it was assumed there would be little or nothing (more like nothing) living in the rock of the crust. Ah but life finds a way (to quote some movie character or another).

The Oregon State research expedition drilled its way through the ocean bottom sediment, a layer of basalt (solidified lava), and into the deep layer of ancient volcanic material called gabbro of the Atlantis Undersea Massif (midway between Africa and South America in the Atlantic Ocean). At that point the deep gabbro has been uplifted much closer to the surface, but still required drilling 4,600 feet (1400 meters) to reach the formation.

There they found many different species of bacteria, all of them ‘anaerobic’ (meaning they don’t need atmospheric oxygen), living primarily on the various organic compounds (hydrocarbons) such as methane and natural gas trapped in the rock. Many of the bacteria are living in areas where the average temperature would be considered lethal for most forms of life. It is not far-fetched to believe that these are bacteria with ancestors that may have developed along with the formation of oil and gas from decaying plant material.

The presence of bacteria embedded in deep rock and unexposed to surface conditions for millions of years – living in relatively great numbers and forming an evolutionary community, an ecosystem – changes the scope and potential for the relatively new fields of study: Biogeology and biogeochemistry. What the bacteria do with the organic compounds in the rock, the chemistry of life in places where we once supposed no life existed, open a new chapter in the book of biology.

It also brings more credibility to the idea that we may find life under similar circumstances on other planets. Namely, Mars. If life ever existed on Mars, and we know that it once had surface water and still has subsurface water, then that life could now be living in the deep rocks – just like it is on Earth. If not Mars, then somewhere else in our solar system, such as the moons of Jupiter (Io, Europa) or moons of Saturn (Titan, Enceladus).

Research Spectrum

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