Washington, Feb 19 (): “New findings by a University of Maryland team of geochemists show that some portions of the Earth’s mantle (the rocky layer between Earth’s metallic core and crust) formed when the planet was much smaller than it is now, and that some of this early formed mantle survived Earth’s turbulent formation, including a collision with another planet-sized body that many scientists believe led to the creation of the Moon.”
“It is believed that Earth grew to its current size by collisions of bodies of increasing size, over what may have been as much as tens of millions of years, yet our results suggest that some portions of the Earth formed within 10 to 20 million years of the creation of the Solar System and that parts of the planet created during this early stage of construction remained distinct within the mantle until at least 2.8 billion years ago,” said UMD Professor of Geology Richard Walker, who led the research team.
Before this finding, scientific consensus held that the internal heat of the early Earth, in part generated by a massive impact between the proto-Earth and a planetoid approximately half its size, would have led to vigorous mixing and perhaps even complete melting of the Earth.
This, in turn, would have homogenized the early mantle, making it unlikely that any vestiges of the earliest-period of Earth history could be preserved and identified in volcanic rocks that erupted onto the surface more than one and a half billion years after Earth formed.
However, the Maryland team examined volcanic rocks that flourished in the first half of Earth’s history, called komatiites, and found that these have a different type of composition than what they, or anyone, would have, expected. Their findings were just published in the journal, Science.
The Fission Theory proposes that the Moon was once part of the Earth and somehow separated from the Earth early in the history of the solar system. The present Pacific Ocean basin is the most popular site for the part of the Earth from which the Moon came. This theory was thought possible since the Moon’s composition resembles that of the Earth’s mantle and a rapidly spinning Earth could have cast off the Moon from its outer layers.