It was once previously thought by scientists that microbial ecosystems existing below Earth’s surface, such as in rocks and continental crust, depended only on the energy from sunlight and photosynthesis that filters down to sub-surfaces. However, according to a recent study, microbial organisms living in these rocky sub-surfaces can get their energy from the hydrogen gas available in the deep rock of Earth’s crusts.
In the study, a team of researchers calculated that Precambrian continental lithospheric, the oldest rock on Earth (aged around 550 million to 4.6 billion years old), produced about 100 times more hydrogen than what scientists previously believed.
One way by which hydrogen gas is produced in these rocks is that the natural radioactivity inside the rocks split water molecules into hydrogen and oxygen atoms, making hydrogen gas available to the microbial organisms living inside the rocks.
This finding is an important one as it gives new insight to the possible places where life could exist on Earth, as 70% of the rock on earth is from Precambrian times.
For more information about the study, you could check out the article by clicking on this link: http://www.nature.com/news/earth-s-deep-crust-could-support-widespread-life-1.16575