Impact events

A Giant Impact Origin For The First Subduction on Earth

By Keith Cowing
Status Report
Geophysical Research Letters
May 8, 2024
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A Giant Impact Origin For The First Subduction on Earth
Billions of years ago, a version of our Earth that looks very different than the one we live on today was hit by an object about the size of Mars, called Theia – and out of that collision the Moon was formed. — NASA (larger image)

Hadean zircons provide a potential record of Earth’s earliest subduction 4.3 billion years ago. It remains enigmatic how subduction could be initiated so soon after the presumably Moon-forming giant impact (MGI).

Earlier studies found an increase in Earth’s core-mantle boundary (CMB) temperature due to the accumulation of the impactor’s core, and our recent work shows Earth’s lower mantle remains largely solid, with some of the impactor’s mantle potentially surviving as the large low-shear velocity provinces (LLSVPs).

Here, we show that a hot post-impact CMB drives the initiation of strong mantle plumes that can induce subduction initiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMB temperature is the primary factor triggering early subduction, with enrichment of heat-producing elements in LLSVPs as another potential factor.

The models link the earliest subduction to the MGI with implications for understanding the diverse tectonic regimes of rocky planets.

A Giant Impact Origin for the First Subduction on Earth, Geophysical Research Letters (open access)


Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻