Collisional Erosion Causes the Modification of Earth's Composition [STUDY]

A team of researchers discovered evidence that suggests the Earth's composition changed over time during its early years due to collisional erosion.

Previous Study on Earth's Composition

According to Phys.org, the group describes their study of the amounts of samarium and neodymium in meteorites and what it reveals about the processes that led to the Earth's current composition in a paper published in the journal Science. Zo Malka Leinhardt of the University of Bristol published a Perspective piece in the same journal issue outlining theories about Earth formation and the team's work on this new effort.

Previous research has suggested that planets form as a result of material colliding in accretion disks that form around stars during their early years. The characteristics of such collisions, such as their tilt angle, are thought to play a role in the resulting makeup of the planets.

It is also revealed that Earth has an iron and nickel core surrounded by a layer of iron silicate mixed with magnesium. The top layer is described as a silicate layer. The density of the material decreases from the core to the crust, making the crust more vulnerable during collisions, according to Leinhardt.

Prior research has also revealed a mystery about the heavier minerals that exist in the crust. According to one theory, they may have been pushed upward due to incompatibilities with other materials. Unfortunately, the theories did not explain why some minerals, such as neodymium, were found in greater quantities in the crust than they should be based on how much can be measured in the core.

Supporting Theory in Relation to the Composition of the Earth

To explain the anomaly, three major theories have been developed. One theory holds that it is an illusion and that there is more of it in the core than can be measured. Another theory is that it is due to differences in the makeup of material from the accretion disk. The third hypothesis proposes that, as heavier materials were pushed up and accumulated in the crust, some were thrown into space during new collisions.

The researchers discovered evidence that backed up the third theory. They measured the amount of neodymium in meteorites and discovered that collisions could have removed up to 20% of the Earth's outer layers. It explained the ratio of heavy minerals like neodymium in the crust to lighter minerals like samarium.

ALSO READ: Planetesimal Theory Is Behind the Formation of Earth, Study Claims

Earth's Composition

Starting from the center, the major layers of the Earth are the inner core, outer core, mantle, and crust. Around 4.5 billion years ago, the Earth's building blocks, known as planetesimals, collided and collapsed under their own gravity, forming these layers.

According to UC Santa Barbara, the heaviest elements (such as iron and nickel) sank to the core while the lighter elements (such as silicon, oxygen, and carbon) rose to form the mantle and crust.

The early-formed core and mantle were degassed, resulting in the formation of the Earth's atmosphere and hydrosphere. Water (77%), carbon dioxide (12%), sulfur dioxide (7%), and nitrogen (3%), with minor amounts of hydrogen, carbon monoxide, sulfur, chlorine, and argon are still abundant gases released from the Earth during volcanic eruptions.