Ancient life found in Earth's mantle rocks

Washington: Scientists have discovered evidence of ancient life in Earth's mantle rocks deep below the seafloor, confirming a long-standing hypothesis that interactions between mantle rocks and seawater can create potential for life even in hard rocks.

The fossilised microbes are likely the same as those found at the active “Lost City” hydrothermal field, providing potentially important clues about the conditions that support “intraterrestrial” life in rocks below the seafloor.

According to researchers, confirmation that life is possible in mantle rocks deep below the seafloor may have important implications for understanding sub-seafloor life across a wide range of geologic environments on planetary bodies.

The team focused on mantle rocks that were originally exposed to seawater approximately 125 million years ago when a large rift split the massive supercontinent known as Pangaea.

The rift, which eventually evolved into the Atlantic Ocean, pulled mantle rocks from Earth's interior to the seafloor, where they underwent chemical reactions with seawater, transforming the seawater into a hydrothermal fluid. The hydrothermal fluid contained hydrogen and methane and seawater contains dissolved carbon and electron acceptors.