Scientists have uncovered evidence suggesting the remnants of another planet embedded deep within Earth have been driving plate tectonics.
According to a study recently published in Geophysical Research Letters, the planet concealed within Earth is Theia, with a relic fragment forming mysterious "blobs" mapped by geophysical data within the lower mantle, just above Earth's outer core.
Theia was a hypothesized Mars-sized planet that collided with early Earth approximately 4.5 billion years ago.
Impact and Formation of the Moon
The collision shattered both infant planets, with most of Theia's material absorbed into Earth while a smaller portion was ejected into orbit, coalescing with Earth debris to gradually form the Moon.
Theia's Mantle Blobs
The blobs—referred to as LLVPs—are regions where the velocity of seismic waves traveling through them drops unusually low.
Study Findings
In the new study, researchers from the California Institute of Technology (Caltech) used computer models to demonstrate the impact LLVPs may have had on Earth's crust over millions of years.
According to the research summary in the scientific journal PHYS, the models show that around 200 million years after Theia's impact, pressure from the LLVPs led to the formation of upwelling plumes extending from near the core to the surface.
This caused portions of the surface to sink, triggering subduction. Subduction eventually led to surface fractures that now serve as boundaries for tectonic plates.
Tectonic Plates
Tectonic plates are essentially fragments of Earth's crust, with an estimated 20 or more major and minor plates constantly shifting. Some plates are subducting, or sinking beneath others, while others are overriding.
Tectonic plates carry continents and oceans on their backs, leading to Earth's landmasses having repeatedly merged into supercontinents surrounded by vast superoceans, before drifting apart again as they do today.
Plate tectonics are also primarily responsible for geological phenomena such as earthquakes, volcanoes, mountain building, and the formation of new ocean floor.
The researchers conclude that their model could explain why some of Earth's oldest minerals show evidence of deep subduction.
Summary
Scientists have identified evidence of a submerged ancient planet within Earth's mantle, which is believed to have significantly influenced plate tectonics, continental drift, and the emergence of geological phenomena.