Scientists Say Huge Structures Inside Earth Are Related to the Origin of Life

"Two enormous structures that sit at the border between the Earth's mantle and its core have puzzled scientists for decades, defying reigning theories of how our planet came to be. In a new study published in the journal Nature Geoscience, a team of researchers led by Rutgers University geodynamicist Yoshinori Miyazaki has come up with a new explanation for these structures - suggesting, provocatively, that their formation may be closely tied to the evolution of life on Earth."

"The continent-sized lumps of dense, hot rock lie almost 1,800 miles beneath the surface under Africa and the Pacific Ocean. They show up in seismic wave readings, indicating major differences in the surrounding composition of rock. "These are not random oddities," said Miyazaki in a statement. "They are fingerprints of Earth's earliest history." "If we can understand why they exist, we can understand how our planet formed and why it became habitable," he added."

"Current theories suggest the early Earth formed a mantle billions of years ago from a massive magma ocean, separating more concentrated from less concentrated material over time, not unlike "frozen juice separating into sugary concentrate and watery ice," per the statement. But finding evidence to support this theory has proven more difficult than expected. Instead of even layers, we've discovered large irregular lumps of "large-low shear velocity provinces," structures characteristic of the Earth's lowermost mantle."

Two continent-sized dense, hot rock structures sit at the core-mantle boundary beneath Africa and the Pacific and register as distinct seismic anomalies. Prevailing formation models invoke differentiation from a primordial magma ocean into layered material. Observations instead reveal large, irregular lowermost-mantle provinces and ultra-low velocity zones that slow seismic waves dramatically. Geodynamic modeling indicates a slow trickle of silicon and magnesium leaking from the core into the base of the mantle can produce dense, irregular accumulations. Those accumulations record early Earth differentiation and may be linked to conditions that made the planet habitable.

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