Seismic surprise! Geologist reconstructs previously unknown tectonic plate

A geologist from the Netherlands has reconstructed a massive and previously unknown tectonic plate, measuring roughly a quarter of the size of the Pacific Ocean.

Suzanna van de Lagemaat, a researcher from Utrecht University in the Netherlands, confirmed the existence of the plate by piecing together its remnants through field research and investigations of mountains in Japan, Borneo, the Philippines, New Guinea and New Zealand. The results of her research are published in Gondwana Research.

Van de Lagemaat’s research substantiates predictions – made by her colleagues a decade ago – that the phenomenon called the Pontus Oceanic Plate existed.

120 ma en
The Pontus oceanic plate / Credit: Suzanna van de Lagemaat, Utrecht University

After systematically reconstructing the movements of current plates in the region between Japan and New Zealand, van de Lagemaat undertook fieldwork in northern Borneo.

There, she says, “we found the most important piece of the puzzle. We thought we were dealing with relics of a lost plate that we already knew about. But our magnetic lab research on those rocks indicated that our finds were originally from much farther north, and had to be remnants of a different, previously unknown plate.”

Relics of Pontus are located on northern Borneo, on Palawan in the Phillippines and in the South China Sea.

The new discovery demonstrates a single coherent plate tectonic stretched from southern Japan to New Zealand, and likely existed for at least 150 million years.

Large tectonic plates make up the Earth’s crust and upper mantle, they lie in pieces on top of molten rock. These plates move over time and some disappear due to subduction, leaving behind fragments hidden in mountain belts. Geologists can also find traces of lost tectonic plates from anomalies in the Earth’s mantle, picked up via disrupted signals from earthquakes.

Understanding the movements of tectonic plates can help explain the planet’s geological history. 

Subscribe to our quarterly print magazine

Please login to favourite this article.