A global team of researchers from the University of Göttingen has studied how the forces exerted by the Zagros Mountains in Iraq’s Kurdistan region have shaped the Earth’s surface over the past 20 million years. Their findings indicate that deep beneath the Earth’s crust, the Neotethys oceanic plate, which once lay between the Arabian and Eurasian continents, is currently fracturing horizontally. This fracture is gradually extending from southeastern Turkey to northwestern Iran. The study highlights the role of deep-seated geological processes in shaping the Earth’s landscape. The research was published in the journal Solid Earth.
Over millions of years, when two continents collide, the oceanic floor that lies between them is forced deep beneath the land masses. Eventually, these continents come together, lifting massive rocks and forming high mountain ranges. The substantial weight of these mountains causes the Earth’s surface to bend downward over time. Sediments that are eroded from the mountains gather in these lowered areas, creating plains such as Mesopotamia in the Middle East. The researchers created models to analyze the angling of the Earth’s surface due to the load of the Zagros Mountains, where the Arabian plate is pushing against the Eurasian plate. By combining the depth of this depression with the computed topography derived from the Earth’s mantle, they were able to replicate the notably deep depression observed in the southeastern part of their study area. Interestingly, they discovered that the weight of the mountains alone couldn’t explain the existence of a 3-4 km deep depression that has filled with sediment over the past 15 million years.
Dr. Renas Koshnaw, the lead author and Postdoctoral Researcher at Göttingen University’s Department of Structural Geology and Geothermics, commented, “It was surprising to find such extensive sedimentation in areas with moderate terrain in northwestern Zagros. This indicates that the downward bending of the land exceeds what could be attributed solely to the weight of the Zagros Mountains.” The researchers suggest that the sinking oceanic plate, which remains attached to the Arabian plate, adds additional downward pressure on the area. Koshnaw further explained, “This plate is exerting a pull from beneath, allowing room for more sediment accumulation. The depression becomes significantly shallower towards Turkey, indicating that the slab has broken off in that region, reducing the downward force.”
The geodynamic model developed in this study could provide insights for various fields. Koshnaw mentions, “This research enhances our understanding of how the Earth’s rigid outer layer operates.” The insights gained may eventually lead to practical applications, such as identifying natural resources like sedimentary ore deposits and geothermal energy, as well as improving assessments of earthquake risks.
This research received funding from the Alexander von Humboldt Foundation.
