Computer models suggest modern plate tectonics are due to blobs left behind by cosmic collision

Amazing stuff about the rocky planet Earth!

"... geologists and seismologists ... has found evidence via computer modeling that suggest giant blobs of material near the Earth's core, believed to have been created by a cosmic collision 4.5 billion years ago, may be responsible for modern plate tectonics. ..."

From the key points and abstract:

"Key Points

• The mantle thermochemical structure left by the Moon-forming impact triggers strong plumes that may have initiated the first subduction
• The strong mantle plumes may rise from a heated core or from large low-shear velocity provinces enriched in heat-producing elements
• Early giant impact events may have a profound influence on the diverse tectonic regimes of rocky planets

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."

Computer models suggest modern plate tectonics are due to blobs left behind by cosmic collision

The Remains of an Ancient Planet Lie Deep Within Earth In the 1980s, geophysicists made a startling discovery: two continent-sized blobs of unusual material were found deep near the center of the Earth, one beneath the African continent and one beneath the Pacific Ocean. Each blob is twice the size of the Moon and likely composed of different proportions of elements than the mantle surrounding it.

A Giant Impact Origin for the First Subduction on Earth (open access)