A new study has found that a huge freshwater pocket that was sucked into the crust of the planet 6 million years ago remains buried under a Sicilian mountain range.
Fresh Groundwater Beneath Sicilian Mountains
It is likely that the fresh water got trapped during the Messinian salinity crisis. This was when the drying up of the Mediterranean took place after a global cooling event that ended up locking ocean water in glaciers and ice sheets. Because of this event, the seabed was likely exposed to rainwater that trickled down the crust of the Earth. This was noted in the study "Extensive freshened groundwater resources emplaced during the Messinian sea-level drawdown in southern Sicily, Italy."
The water ended up building up and forming an aquifer that spanned 700 to 2,500 meters deep under the Hyblaean Mountains in Sicily, Italy. Since then, the water has not budged.
In the study, the researchers looked into groundwater reserves deep within and around the Gela formation, which is an oil reservoir and a host of many deep wells. They harnessed data from these wells that is publicly available.
The researchers made 3D models of the said aquifer and estimated that it contains 17.5 cubic kilometers of water, which is double the water quantity held by Loch Ness in Scotland.
The 3D models were then used to go back in time and reconstruct the study area's prior geology, which stretched from the Hyblaean Plateau to the Malta Plateau. Results revealed that during the Messiian period, roughly 7.2 million to 5.3 million years ago, the water infiltrated the crust of the Earth thousands of feet below sea level at present.
During the crisis, sea levels were observed to drop 2,400 meters below present levels in areas of the Mediterranean.
Groundwater Build Up
Geoscientist Lorenzo Lipparini from the University of Malta and the National Institute of Geophysics and Volcanology of Italy, who is also the study's lead author, explains that the groundwater pool is built up in a carbonate rock layer that serves as a sponge of some sort, where fluids reside in the pores between the particles of rock.
However, for this explanation to stand, it is necessary for the researchers to find a channel of meteoric water, which is from snowfall and rain, on the seabed of the Mediterranean. The researchers note that the 300-meter Malta Escarpment submarine cliff is a potential candidate for this, which means that the lacking conduit could be in the escarpment.
The salinity crisis took place for 700,000 years and abruptly ended with the extremely fast sea level rise that could have altered pressure conditions and deactivated the entire mechanism.
There is also a possibility that mineral deposits and sediments ended up sealing off the conduit in the escarpment as the salinity crisis took place. This would have prevented the mixing of sea and fresh water in the Gela formation.
The researchers are hopeful that the fresh groundwater could be pumped in order to help combat the water scarcity issue in Sicily. They also hope that the findings will lead to similar explorations of groundwater across the Mediterranean.
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