Chinese Scientists Uncover Formation of Global Seamounts—-Chinese Academy of Sciences

All 40,000-plus ocean seamounts originate from deep mantle plume activity, according to a study by the Chinese Academy of Sciences published June 10 in Nature Geoscience. Led by Professor Liu Lijun, researchers used high-resolution modeling to prove that both linear chains and isolated cones stem from thermal anomalies at the core-mantle boundary.

How do mantle plumes create scattered seamounts?

Mantle plumes originating from the core-mantle boundary generate asthenospheric thermal anomalies that act as “seamount brewing zones.” According to the research team at the Institute of Geology and Geophysics (IGG) of the Chinese Academy of Sciences (CAS), these heat anomalies trigger partial melting beneath tectonic plates, creating volcanic activity.

While some plumes create organized chains, others disperse. The study found that during the early ascent of a plume, heat accumulates beneath young lithosphere. This process creates the wide, scattered distributions of volcanic cones seen in regions like the Western Pacific Seamount Province.

Why does this update the classical hotspot model?

The classical hotspot hypothesis explains the formation of volcanic chains, such as the Hawaiian Islands, where a plate moves over a stationary heat source. However, the IGG research team noted that only about 50 seamount chains globally conform to this specific model.

The new findings extend this model by accounting for the thousands of isolated seamounts that don’t form chains. By reconstructing 270 million years of Earth’s interior dynamics, the team demonstrated that these isolated cones aren’t random. They’re the result of the same deep-Earth mechanisms as the chains, just manifesting as dispersed thermal anomalies rather than concentrated points.

What happens when mantle plumes split?

The IGG model reveals that mantle plumes don’t always remain single columns of heat. They can split either at their roots in the lower mantle or within the mantle transition zone. This splitting creates secondary mantle plumes.

These secondary plumes increase the number of hotspots available to create volcanism. According to the study, the resulting hot material persists in the asthenosphere over geological timescales, migrating and dispersing via mantle convection. The researchers found a significant linear correlation between these modeled residual temperatures and the actual elevations of observed seamounts.

How do subducting slabs influence seamount formation?

The interaction between sinking tectonic plates and the deep mantle plays a critical role in where seamounts appear. Garrett Apuzen-Ito, a professor at the University of Hawaii, stated in a commentary that the IGG model provides a richer picture of these processes.

Apuzen-Ito noted that scattered intraplate seamounts result from the dynamic interaction between subducting slabs and the large low-shear-velocity provinces located above the core-mantle boundary. Essentially, the “sinking” of old crust helps shape the “rising” of the heat that creates seamounts.

What are the future trends in deep-ocean mapping?

This discovery shifts the focus of marine geology toward identifying “seamount brewing zones.” Future research will likely prioritize the mapping of asthenospheric thermal anomalies to predict where undiscovered seamounts might exist.

As computational power increases, scientists can move from 3D reconstructions to real-time simulations of mantle flow. This will allow geologists to better understand the lifecycle of a seamount, from the initial plume ascent at the core-mantle boundary to its eventual erosion or subduction.

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