6 million-year-old ‘groundwater pool’ discovered beneath Sicilian mountains

New research has revealed that there is a substantial reservoir of freshwater, drawn into Earth's crust six million years ago. It still remains deeply buried beneath the Hyblaean Mountains in Sicily. This freshwater, believed to have been trapped during the Messinian salinity crisis, when the Mediterranean Sea dried up due to the rising ocean floor around the Strait of Gibraltar. If reports are to go by, it has persisted in an aquifer stretching 2,300 to 8,200 ft beneath the surface.

According to a study published in the journal Communications Earth & Environment on November 22, rainwater likely exposed the seabed during the crisis, thereby forming the aquifer that now lies beneath the mountains and has remained unchanged since its inception.

Researchers delved into deep groundwater reserves around the Gela formation, constructing 3D models to estimate the aquifer's size at 4.2 cubic miles — over twice the volume of Scotland's Loch Ness.
Utilizing these 3D models, the scientists reconstructed the geological history of the region, revealing that during the Messinian period (7.2 million to 5.3 million years ago), freshwater penetrated the Earth's crust thousands of feet below current sea levels.

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The accumulated 'fossil groundwater pool' settled in carbonate rocks, resembling a sponge where fluids occupy the pores between rock particles.

To authenticate their discoveries, the researchers looked for a pathway for meteoric water, which includes precipitation from rain and snowfall, connecting the Mediterranean seabed to the deeply buried Gela formation. The Malta Escarpment, a submarine cliff stretching 190 miles from the eastern margin of Sicily, emerged as a credible link, potentially serving as the missing channel for the water flow.

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The Messinian salinity crisis, lasting around 700,000 years, concluded abruptly with a rapid rise in sea levels that may have altered pressure conditions and deactivated the groundwater mechanism. Alternatively, sediment and mineral deposits could have sealed off the conduit along the Malta Escarpment during the crisis, preventing the mixing of seawater with the freshwater in the Gela formation in the ensuing millions of years.
With hopes of addressing water scarcity in Sicily, the researchers anticipate the possibility of extracting this freshwater resource. Additionally, they are keen to undergo similar deep groundwater exploration initiatives in other Mediterranean regions.