Our Faculty Members’ Study is in Nature Geoscience

ITU Eurasia Institute of Earth Sciences faculty members Prof. Dr. Gültekin Topuz and Assoc. Prof. Dr. Oğuz Hakan Göğüş together with Prof. Dr. Russell Pysklywec and Ph.D. student Erkan Gün from University of Toronto proposed a new hypothesis about the tectonic movements and deformation processes of the oceans and continents that have been going on for millions of years. The research results were published in Nature Geoscience, one of the most prestigious journals of geosciences, in May.

Using geodynamic numerical modeling based on the physical properties of the Earth, the researchers showed that small-scale continental/plate fragments (microcontinents) drifting over the oceans are being fragmented (expanding) by enormous tectonic forces (slice pulling force) long before predicted. The results of the modeling, supported by geological data such as temperature-pressure diagrams and expansion factors, reveal that the expansion occurred (several hundred kilometers) away from the plate boundaries before the continent-continent collision.

In summary, according to plate tectonics theory, the hotter and fluid material below the plates/lithosphere moves over the asthenosphere mantle due to thermomechanical convection currents. This movement varies from place to place and can reach several centimeters per year. Thus, as the oceanic and continental plates drift around and collide with each other over million-years-long periods and dive beneath the mantle deep below (because they are heavy), they produce various geological processes such as volcanoes, earthquakes, mountain (orogenic) belts and related structures such as faults and folds at the plate boundaries.

“Discovery of new geologic process calls for changes to plate tectonic cycle”

Studies up to now suggested that the expansion of these plates (continents) occurs under the influence of gravitational forces of the Earth's crust, which rises and gets compressed behind magmatic arcs, for example after reaching a subduction zone where the massive Pacific plate dives beneath the smaller Philippine plate or after a continent-continent collision such as the Himalayas.

Erkan Gün, a graduate of ITU Eurasia Institute of Earth Sciences who is currently pursuing a Ph.D. in University of Toronto, said, “Our work tested models with hundreds of parameters and the findings showed that microcontinents are being pulled apart/expanding during the subduction process at a remarkably early phase of the tectonic cycle.” The researchers term this mechanism a “subduction pulley”. It was also stated that the results will shed light on our understanding of how some geological processes, whose cause is not yet understood, occur throughout the Alpine Himalayan mountain belt. The research was made possible with support from SciNet and Compute Canada, the Natural Sciences and Engineering Research Council of Canada (NSERC), and the Scientific and Technological Research Council of Turkey.

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