340-million-year-old ocean crust discovered
A new understanding of how continents formed could be just one of the findings.
Pizza isn't the only thing with a crust. The ocean has one also (a couple actually), and a sliver of it at the bottom of the Mediterranean Sea may be more than 100 million years older than any was previously thought to be. It's all part of a recent discovery that offers new insight into what Earth looked like as continents shifted around the globe hundreds of millions of years ago.
Under the patronage of EcoOcean, a marine research and education organization located in Herzliya, Israel, Granot made several trips out to sea on the boat Mediterranean Explorer.
Plate reconstruction maps at 20 million-year intervals around the time the Pangaea Supercontinent completed its formation and a new ocean was formed in what is now the eastern Mediterranean Sea. (Photo: Roi Granot)
"People have been working on the topic for 40-50 years so I was sure that I would not find anything new, basically," Granot told From The Grapevine of his research. Fortunately, he was wrong.
Granot towed magnetic sensing equipment to collect 4,300 miles of marine magnetic profiles across the Herodotus and Levant Basins, located in the eastern Mediterranean, to study the nature and age of the underlying igneous crust.
He then used the magnetic data to analyze the nature of the crust in the Herodotus Basin, and found that the rocks are characterized by magnetic stripes – the hallmark of oceanic crust formed at a mid-ocean ridge. As magma at a mid-ocean ridge axis cools, magnetization of the minerals in the newly forming rocks align with the direction of Earth's magnetic field.
By using this principle and identifying skewed patterns in the magnetic stripes, Granot showed that the oceanic crust in the Herodotus Basin could be as much as 340 million years old.
"It took a lot of time to process the data, but once I saw it I was very surprised. I was kind of shocked," he told us.
Oceanic crust is typically recycled back into the Earth's mantle – the layer between the crust and the outer core – relatively rapidly. Thus, most oceanic crust is less than 200 million years old.
Granot suggests that the crust might be a remnant of the ancient Tethys Ocean, which existed before the opening of the Indian and Atlantic oceans during the Cretaceous period, and said the discovery has many implications as far as understanding how the region formed, and with it the continents it spawned.
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