A new study published in the journal Communications Earth & Environment provides compelling evidence that the Zanclean megaflood refilled the Mediterranean Sea, ending the Messinian salinity crisis, which lasted between 5.97 and 5.33 million years ago. The study, conducted by international team of scientists, including researchers from the University of Southampton, identified geological features around Southeast Sicily that indicate a massive flood occurred across the region.
The authors of the new study examined over 300 asymmetric ridges in a geological corridor crossing the "Sicilian threshold," a submerged land bridge that once separated the western and eastern basins of the Mediterranean. Analyzing seismic imaging data, the researchers found a "W-shaped channel" on the continental shelf east of the Sicilian threshold. The shape and location of this channel suggest it acted as a "huge funnel" toward the Noto submarine canyon at the time of the megaflood, according to El Economista.
By taking samples from these ridges, the team discovered they were topped with a layer of rock debris corresponding to the boundary between the Messinian and Zanclean periods. This layer contained eroded materials from the surrounding region, indicating these materials were deposited rapidly and with "considerable force."
"The Zanclean megaflood was an awe-inspiring natural phenomenon, with discharge rates and flow velocities that eclipse all other known floods in Earth's history," said Dr. Aaron Micallef, lead author of the study and researcher at the Monterey Bay Aquarium Research Institute in California, according to Science Daily. "These findings not only shed light on a critical moment in Earth's geological history but also demonstrate the persistence of landforms over five million years," he added, as reported by GEO France.
"The morphology of these ridges is compatible with erosion by large-scale, turbulent water flow with a predominantly north-easterly direction," said Paul Carling, emeritus professor at the University of Southampton and co-author of the study. "They reveal the immense power of the Zanclean Megaflood and how it reshaped the landscape, leaving lasting imprints on the geological record," he added.
Until recently, scientists believed that the dry period of the Messinian salinity crisis ended gradually over a period of 10,000 years. This idea was challenged by evidence of a single massive flooding event known as the Zanclean megaflood. The discovery of an erosion channel extending from the Gulf of Cádiz to the Alboran Sea in 2009 pointed to a massive flood lasting from two to 16 years, which ended the Messinian crisis much more abruptly than previously believed.
The team developed computer models of the megaflood to understand how the water might have behaved. The model suggests that the flood would have changed direction and increased in intensity over time, reaching speeds of up to 32 meters per second (72 miles per hour). This allowed it to carve deeper channels, erode more materials, and transport them over longer distances.
According to GEO France, the Zanclean megaflood is estimated to have had a discharge of between 68 and 100 Sverdrups, with one Sverdrup equivalent to one million cubic meters per second, or approximately 40,000 Olympic-sized swimming pools pouring into the Mediterranean Sea every second, or 68 billion liters every second.
During the Messinian salinity crisis, which occurred between 5.97 and 5.33 million years ago, the Mediterranean Sea was isolated from the Atlantic Ocean and evaporated, leading to enormous salt deposits that reshaped the region's landscape.
"Our research provides the most compelling evidence of this extraordinary event," emphasized Micallef, as reported by GEO France.
According to Science Daily, the research was supported by the National Geographic Society, Deutsche Forschungsgemeinschaft, and the David and Lucile Packard Foundation.
The article was written with the assistance of a news analysis system.