A long-lost oceanic plate, a relic of the ancient Neotethys ocean, is diving deep into Earth's mantle, according to researchers. This geological phenomenon is dragging down the crust above and affecting the landscape between the Arabian and Eurasian plates. The Neotethys ocean, which closed over 20 million years ago, once lay between these two regions. Formed approximately 195 million years ago when the supercontinent Pangaea split into Laurasia and Gondwana, the Neotethys ocean is still influencing the earth's geology today.
The remnants of the Neotethys oceanic crust continue to impact the region as it plunges into the mantle beneath the Zagros Mountains in Iraq. This subduction process is tearing the plate apart, relieving some of the load from the overlying crust and altering the landscape. The tear is advancing towards northwest Iran, reshaping the geological dynamics in its path. Researchers note that on the southeastern side of this tear lies an unusually thick layer of sediments, ranging from 1.9 to 2.5 miles deep.
The collision between the Arabian and Eurasian plates, driven by the dragging force of the oceanic plate, formed the Zagros mountain range. Over millions of years, these mountains eroded into a depression now known as the Mesopotamian plain, through which the Tigris and Euphrates rivers flow. The sediments from these eroded mountains contributed to forming this fertile plain.
Faults created by the collision of these tectonic plates also result in large, deadly earthquakes. The continental portion of the Arabian plate, underpinning modern-day Iraq and Saudi Arabia, was dragged behind in this tectonic process, colliding with Eurasia and shaping the landscape. This ongoing geological activity suggests that the Neotethys oceanic crust retains its influence over the region.
The study detailing these findings was published in the journal Solid Earth on November 25, 2024. Renas Koshnaw, a researcher in geology at Göttingen University in Germany, remarked on the phenomenon:
"This plate is pulling the region downward from below."
Koshnaw further explained how the geological activity varies across different regions:
"Towards Turkey, the sediment-filled depression becomes much shallower, suggesting that the slab has broken off in this area, relieving the downward pull force."
This shedding of geological weight indicates a complex interaction between tectonic forces beneath Earth's surface. As researchers continue to study these processes, they gain insights into how ancient oceanic plates continue to shape contemporary landscapes.
