Cracks in the Earth Control How Much Ocean Water Gets Sucked Under During Continental Breakup
Scientists have uncovered a fascinating new link between fault lines and the amount of seawater sucked deep into the Earth during continental breakup. A team led by geoscientists at the University of Oxford has shown, for the first time, that active faults control how much water reaches the Earth’s mantle over geological timescales.
Faults: Earth’s Water Gatekeepers
When ocean water and carbon plunge into the mantle, they react with dry mantle rock called peridotite. This forms a slippery green mineral called serpentinite. Dr Gaye Bayrakci and Professor Tim Minshull from Oxford’s Ocean and Earth Science department, alongside colleagues at southampton/" title="Southampton" data-wpil-keyword-link="linked">Southampton and other institutions, mapped where serpentinite forms using seismic sound waves.
“The link between fault activity and formation of serpentinite was something we might have hoped for but did not really expect to see so clearly,” said Dr Bayrakci. Their sound waves travel through the crust and mantle, detected by instruments on the seafloor. The speed of these waves reveals how much serpentinite is present.
Active Faults Direct the Flow of Seawater
The study found the amount of serpentinite matched the movement on each fault – meaning the longer a fault stays active, the more water it drags down. This shows that seawater only reaches the mantle when faults are moving, making these cracks the ultimate regulators of Earth’s underwater plumbing.
“This implies seawater reaches the mantle only when the faults are active and that brittle processes in the crust may ultimately control the global amount of seawater entering the solid Earth,” said Dr Bayrakci.
Hotspots for Hydrothermal Life?
In places like mid-ocean ridges and subduction zones, the flow of water through faults supports hydrothermal vents packed with unique ecosystems. The researchers estimate that in continental rifting zones like the Deep Galicia Margin, the rate of seawater entering the mantle is similar to these hotspots.
This suggests continental breakup zones may have hosted hydrothermal systems capable of supporting diverse life in Earth’s ancient past.
Why This Matters: From Earthquakes to Ecosystems
Professor Tim Reston from the University of Birmingham, co-author of the paper published in Nature Geoscience, explained the wider significance:
“Understanding the transport of water during deformation has broad implications, ranging from hydrothermal systems to earthquake mechanics. The new results suggest a more direct link between faulting and water movements than we previously suspected.”
This breakthrough helps us understand how Earth’s cracks control water’s journey deep below, affecting everything from geological activity to the ecosystems thriving on underwater volcanoes.
