A group of Canadian and Turkish researchers analyzed seismic and petrological data from four Pacific plateaus and compared them with models of plate subduction activity. It turned out that these plateaus appeared as a result of volcanism, and the subducting plate was constantly deformed due to gravity.

According to the prevailing view of geotectonics, lithospheric plates are rigid and immobile. Their deformation occurs only at the boundaries, at the points of meeting with other plates. Intraplate deformations resulting from stress, gravitational instability, and other processes are believed to be more characteristic of continental plates. This was not detected in the oceans: such deformations are not characteristic for them, since changes in the thickness of the oceanic crust (about 5-10 kilometers) are less than the continental thickness. However, there are places on these plates that are more prone to tectonic changes; oceanic plateaus formed by basaltic eruptions on the ocean floor.

A group of geologists from Canada and Turkey examined seismic and petrological data from the modern Pacific plateaus and compared them to models of ocean plate movement in the western Pacific subduction system. The results may explain mysterious intra-plate deformations occurring simultaneously with the drift phase, the researchers said. The scientific study was published in the journal Geophysical Research Letters.

Geologists have examined evidence of four Pacific plateaus: the Ontong Java and Manihika atolls (both atolls formed on the tops of large seamounts), and the Shatsky and Hess dunes. Studies of Ontong Java have shown that before reaching the collision boundary of lithospheric plates (the subduction zone), the seamount on which the atoll is located experienced several episodes of major magmatic activity, which scientists explained by floods from the sky. Lithosphere and extensional tectonics that occurred 5 years ago.

Similar activity was found in the Shatsky plateaus, where tectonic tension occurred during the drift of the plateau towards Japan and the Izu-Bonin troughs. 900 kilometers away is the Hessian Plateau, formed about 110 million years ago. Seismic data of this plateau showed that vertical displacements along the faults could reach three kilometers and were stepped structures. They probably emerged in the Middle Eocene and were active during the accumulation of precipitation. According to the article’s authors, the underwater mountain on which Manihika Atoll is located appeared about 123 million years ago and was soon divided by faults into three subplateaus.

The researchers then set out to understand how tectonic stretching could occur away from subduction zones. To do this, they created several models showing that oceanic plateaus have been continuously deformed since the beginning of drift. Geologists explained these deformations by the gravity of the subduction plate, that is, the plate on which the other is moving. Similar collisions occur frequently between continental and oceanic plates.

“There is evidence that volcanism has occurred in these places as a result of such plate damage in the past – perhaps intermittently or continuously, but it is not clear whether this is happening now. We cannot be sure because the plateaus lie thousands of meters below the ocean surface, and sending research ships to collect data is a huge challenge.” “It requires effort. Therefore, we hope that our article will draw attention to the plateau and collect more data,” he said.