Using a self-developed model, Chinese scientists have uncovered the origin of global seamounts and recreated the subduction history of the last 270 million years.

According to their study published in the journal Nature Geoscience, the formation and evolution of both linearly extending seamount chains and scattered isolated seamounts are intimately associated with the thermal activities of the asthenosphere driven by the upwelling of mantle plumes from the core-mantle boundary.

Latest surveys reveal there are over 40,000 seamounts in nearly every ocean basin, dispersed at random throughout the world's oceanic plates.

The conventional hotspot hypothesis suggests that high-temperature mantle plumes originating from the top of the Earth's core trigger melting of rocks beneath drifting plates, thereby forming long chains of submarine volcanoes in areas such as the Hawaiian Islands.

However, only a limited number of seamount chains, totally over 50 of them, echo such hypothesis. This reveals a significant mismatch between the hotspot model and the actual quantity, scale and spatial distribution of global seamounts.

This poses a critical question: Do all seamounts originate from hotspots and mantle plumes? And if so, how can so few hotspots produce so many seamounts spread across the globe?

Researchers used a global data assimilation model to replicate current mantle plume hotspot locations and asthenosphere thermal structure. They also predicted the spatiotemporal evolution of key hotspots like Hawaii and their corresponding deep mantle plumes.

In the Pacific region, for instance, during the early stage of mantle plume upwelling, a large volume of hot plume material accumulated beneath the young Pacific plate, creating a broad thermal anomaly in the asthenosphere, according to the study.

During the subsequent evolution, mantle plumes could split from the root within the lower mantle or the middle part of the mantle transition zone, generating secondary mantle plumes. This further increased the number of shallow hotspots and provided conditions for the formation of additional seamount chains.

This mechanism offers a unified framework for the formation of intraplate seamounts worldwide, substantially expanding the classical mantle plume hypothesis, said Liu Lijun, a researcher with the Institute of Geology and Geophysics, Chinese Academy of Sciences.

The simulation was conducted on the new-generation Tianhe supercomputer at the National SuperComputer Center in Tianjin, north China. (Xinhua)