6 Million Year Old Canyon Unearthed In Mediterranean Sea; Found To Have Formed Before Salt Piled In Seabed

A six-million-year-old canyon was unearthed in the Mediterranean Sea, with experts saying that this formed before salt piled in the seabed.

Hypersaline Basin

Researchers noted that approximately six million years ago, the entire Mediterranean Sea turned into a hypersaline basin when the Gibraltar gateway to the Atlantic Ocean narrowed and evaporation exceeded freshwater input.

Consequently, marine fauna died and massive deposition of salt on the seafloor had led to the formation of the world's youngest salt giant.

A fundamental observation related to this enigmatic period is a remarkable erosional surface that was found to be associated with 100 s-of-m deep canyons that were incised across the Mediterranean's continental margins during the crisis.

A recent study explained that such canyons across the Levant margins were described in the 1970s and, later, in the 2000s, they were shown to be the gateway for shallow, sinuous, submarine channels that continued towards deeper parts of the basin.

Although it could have been assumed that these channels end as terminal sedimentary lobes in the Levant Basin, researchers have shown that they contributed to a much wider sedimentary system in the Eastern Mediterranean Sea.

Meanwhile, farther west, they merged into a nearly 500-m-deep and ∼ 10-km-wide canyon, which was named after the nearby Eratosthenes Seamount.

''This remarkable canyon was excavated at the beginning of the MSC prior to salt deposition. We suggest that incision took place during Stage 1 of the MSC, but we cannot rule out faster incision (10s of ky) at the end of Stage 1 (∼5.60 Ma), or at its very beginning (∼5.97 Ma),'' experts said.

Based on the study, the Eratosthenes Canyon was excavated subaqueous and researchers suggested that incision was caused by gravity currents, such as sediment-laden turbidites and/or dense brines.

Scientists argued that the increased salinity at the beginning of the crisis and a possibly limited sea level fall - whose amplitude should be investigated - had triggered these gravity currents.

This then destabilized the continental margin and carving the seabed wherever it was steep enough. It was further pointed out that unlike the more coastal gullies, the canyon had no older "pre-salt" roots.

Deep Basin Channel

Experts said that the Eratosthenes Canyon extends a deep basin channel, which is sourced by the Afiq and Ashdod canyons farther away in the Levant continental margin.

Scientists said that the newly discovered canyon sits within a wider network of canyons and channels in an area known as the Levant Basin.

This basin extends from the coast of Syria in the north to Gaza in the south, and northwest toward Cyprus.

To the northwest of the canyon, beyond the Eratosthenes seamount, sits the much deeper and older Herodotus basin, which receives currents loaded with sediment from the southeast.

These currents may have crossed the area that now boasts the Eratosthenes Canyon long before it was incised, according to the recent study.