How Earth Gained Carbon

Carbon, the key ingredient for all life on the planet, is the result of a planetary collision about 4.4 billion years ago, a theory suggests.

09:14 08 September 2016

Based on a widely accepted idea called Late Veneer Hypothesis, Earth was formed without various elements including sulphur, carbon, hydrogen, and nitrogen. The theory suggests that the volatiles were added after Earth’s core had finished forming.

 

Rajdeep Dasgupta, a co-author of the study from Rice University in Houston, Texas, said: "The challenge is to explain the origin of the volatile elements like carbon that remain outside the core in the mantle portion of our planet," 

 

Yuan Li, from the Guangzhou Institute of Geochemistry at the Chinese Academy of Sciences, said: "Any of those elements that fell to Earth in meteorites and comets more than about 100 million years after the Solar System formed could have avoided the intense heat of the magma ocean that covered Earth up to that point,"

 

"The problem with that idea is that while it can account for the abundance of many of these elements, there are no known meteorites that would produce the ratio of volatile elements in the silicate portion of our planet."

 

The team conducted laboratory experiments to recreate the high-pressure and high-temperature conditions that exists deep inside the Earth and other rocky planets. They found that one scenario that can help add things up in the carbon-to-sulphur radio and carbon abundance was a planetary collision about 4.4 billion years ago.

 

"Because it's a massive body, the dynamics could work in a way that the core of that planet would go directly to the core of our planet, and the carbon-rich mantle would mix with Earth's mantle," said Dr Dasgupta.