A significant geological discovery has revealed the existence of an ancient tectonic plate previously thought to have vanished. The Pontus tectonic plate, estimated to cover a quarter of the Pacific Ocean, has been rediscovered after being absent for approximately 20 million years.
Remnants of this plate, which once formed the foundation of the South China Sea, can now be traced through rock fragments in the mountains of Borneo, as well as seismic data indicating the presence of a large rock mass within the Earth's mantle.
A Geological Mystery in the Junction Region
The hypothesis about the existence of the Pontus tectonic plate first emerged from an analysis of geological data conducted by Suzanna van de Lagemaat and her team at Utrecht University. Their research focused on the Junction Region, an area of complex tectonic activity in the Asia-Pacific, spanning from Japan, Borneo, the Philippines, Papua New Guinea, to New Zealand.
In a detailed study of the rocks in the mountains of Borneo, van de Lagemaat identified previously unrecorded plate fragments. This discovery has been a major surprise in the field of geology, as it highlights the complexity of subduction processes and mountain formation.
Magnetic Traces: The key to Understanding Geological Gaps
While searching for remnants of the ancient Phoenix plate in Borneo, researchers stumbled upon an unexpected discovery. Van de Lagemaat explained that the magnetic properties of rocks can reveal when and where they were formed, as Earth's magnetic field becomes "locked" into the rocks during their formation and varies by latitude.
Using computer models to investigate the region's geology over the past 160 million years, the team identified a gap between South China and Borneo. The ocean once thought to be above the ancient Izanagi plate was not beneath it, but instead, rocks from Borneo filled this mysterious void.
Pontus Plate: A Forgotten History
Researchers estimate that the Pontus plate, which was part of Earth's crust before the breakup of the supercontinent Pangaea, covered about a quarter of the Pacific Ocean and lay beneath the ocean that separated Eurasia and Australia. As Pangaea split, the plate is believed to have been consumed by another tectonic plate, which moved the Philippines and Borneo into their current positions.
A reconstruction published in the journal Gondwana Research suggests that the Pontus plate formed at least 160 million years ago, with rock samples collected from Borneo dating back 135 million years. Though once vast, the Pontus plate gradually shrank and was eventually pushed beneath the Australian and Chinese plates before disappearing 20 million years ago.
Previous research also hinted at the existence of the Pontus plate through images of Earth's mantle, which revealed a large, unidentified plate now confirmed to be the remnants of the Pontus plate.
