The origins of continent-sized blobs of matter in the Earth’s mantle, below where Africa and the Pacific Ocean are located, have eluded scientists for decades.
But a new study argues the mysterious matter could be from the Earth collision that led to the Moon’s formation.
The leading idea of the moon’s origin is that a protoplanet, called Theia, collided with Earth more than 4 billion years ago. Matter was ejected before gravity started to form its shape.
Back inside Earth’s mantle, evidence has shown these blobs thousands of miles below the crust are made of different material than what surrounds them.
Arizona State University professor Steven Desch is a co-author of the study. He says the team modeled different scenarios of Theia’s composition and collision with Earth.
“There’s entire sections of the planets that are not really well fragmented, so we make some arguments in the paper that it could maintain its cohesion for the thousands of years it takes for the material to sink," Desch said.
He says parts of the other planet, believed to be about the size of Mars, may have burrowed beneath the Earth’s Crust.
"Over millions of years, the heat from the Earth's core causes it to convect like boiling water on a stove, but in slow motion. That convection, it causes the material at the core mantle boundary to pile up into these continent-sized things," Desch said.
The paper was published in the journal Nature.
