A study led by the Australian National University (ANU) explores what happened in the Mediterranean during the mega-flood, when the Mediterranean was inhabited five million years ago and helped restore its current order. During the process, A giant 1.5 kilometer high waterfall has occurred in the region of present-day Sicily that helped flood the entire eastern half of the Mediterranean basin.
Dubbed the Zanclean Mega-Flood, it was the largest flood known to science. He transformed the Mediterranean basin from a barren saltwater pond into the bustling marine ecosystem we know today. ANU research, Nature GeologyIt sheds light on how this transformation took place.
Today, it is possible to find seashells in the Troodos Mountains, the largest mountain range of the island. This is because the Mediterranean has a turbulent history filled with tectonic activity, sinking and rising islands, and flooding.
Udara Amarathunga, lead author and ANU PhD researcher in paleoenvironments, said that the Zanclean flood It was one of the most abrupt global environmental changes since the mass extinction that wiped out the dinosaurs.. The researcher thinks that this is the “Mediterranean rebirth”.
Gibraltar’s ‘door’ is closing
The mega-flood triggered the end of the Messinian Salinity Crisis (MSC). Mediterranean basin partially dried up as the Atlantic-Mediterranean passage was closed [Gibraltar]leaving large salt deposits and killing most life forms”, explains in Cosmos magazine.
Amarathunga added that the MSC began six million years ago when the European and African continental plates pushed against each other, separating the Mediterranean Sea from the Atlantic at the point where Gibraltar is today.
Amarathunga says that this “gate” is not completely closed and that little access to the Mediterranean is allowed. But It closed completely 5.6 million years ago, and this is the peak of the salinity crisis.”
While scientists aren’t sure of the exact extent of the Mediterranean’s drying up, Amarathunga says they believe their levels dropped by 1-2 kilometers and formed two different basins: the eastern and western basin, now separated by Sicily.
A giant waterfall 1.5 kilometers high
But what happened that the Mediterranean ceased to be an uninhabitable saltwater lake?
Slowly but surely, Amarathunga explains: Erosion in Gibraltar resulted in small amounts of water seeping from the Atlantic into the Mediterranean. The mega-flood hypothesis was first developed in 2009 by Spanish scientist Daniel García-Castellanos, and after this initial slow flow, The “dam wall” would break, causing large volumes of water to enter the Mediterranean.
This would have created a massive waterfall 1.5 kilometers high at the height of Sicily and flooded the other half of the basin.
The energy produced by the enormous movement of water in a single day at the peak of the flood would have been equivalent to 500 times the energy produced by Niagara Falls in one year. The Mediterranean Sea is predicted to rise more than 10 meters per day at the peak of the flood.
The rest of the world’s seas suddenly fell nine meters
“It would have been the most sudden flood in recorded history,” says Amarathunga. The magnitude of this phenomenon is that “as the Mediterranean fills andglobal sea level dropped by nearly nine meters.”
Immediately after the eastern Mediterranean’s flood surface, there is an “organic rich layer” in the water, indicating low oxygen levels, as oxygen leads to oxidation of this organic matter. This layer is not seen in the western basin. These anaerobic dead zones in the eastern Mediterranean indicate that the eastern basin was without oxygen after the flood.
The accumulation of megacells and layers rich in organic matter took place in stages.
First, the Western Mediterranean basin is filled. Then, when the land barrier that existed on Sicily’s peak is broken, a huge waterfall forms in the east. But this waterfall, as Amarathunga’s work shows, may have brought with it large amounts of salt to the eastern basin.
“Our interpretation is towards the end of the flood, both basins mix. But because of the energy of the storm water, all the salt is transferred from this waterfall to the eastern basin,” says Amarathunga. “Now this salt needs to be transferred to the Atlantic. We used another model to estimate how long it would take to get the salt into the Atlantic.”
“Our study shows that It took another 26,000 years to remove all the excess salt. and return to the Mediterranean Sea as a normal sea basin,” he adds.
This long transition period was hitherto unknown to scientists. However, the mega-flood hypothesis is subject to some controversy. Some scientists suggest that the Mediterranean never dried out on a large scale. But This new ANU study provides evidence that strengthens the mega-flood hypothesis.
Amarathunga said such a rapid and massive transformation is rare, making the Zanclean flood a unique example of how quickly entire ecosystems can change.
Reference work: https://www.nature.com/articles/s41561-022-00998-z
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