Diamonds found in ancient rocks have the ability to conserve volatile gases. Taking this ability into consideration, a team of scientists studied these diamonds to understand the basic chemical composition of the Earth's atmosphere. The unique study revealed that the Earth's chemical composition began at least 2.7 billion years ago. The diverse life on Earth is only possible because of the basic chemical composition of the planet.
The study also found that one of the basic conditions necessary to support life, the presence of life-giving elements in sufficient quantities, which appeared right after Earth was formed, have remained fairly constant.
"The proportion and make-up of volatiles in the atmosphere reflects that found in the mantle, and we have no evidence of a significant change since these diamonds were formed 2.7 billion years ago", lead researcher Dr Michael Broadly said while presenting the work at the Goldschmidt Geochemistry Conference.
The full findings of the study were presented at the Goldschmidt Conference 2021 which is being held virtually from 4-9 July.
Volatiles like hydrogen, nitrogen, neon, and species composed of carbon are light chemical elements and compounds that can be readily vaporised due to heat, or pressure changes. They are necessary for life, especially carbon and nitrogen. Yet, not all planets or satellites are rich in volatiles. Earth along with Venus are rich in volatiles. But Mars and the Moon lost most of their volatiles, as per experts.
According to experts, a planet rich in volatiles has a better chance of sustaining life, this is why most of the search for life on planets surrounding distant stars (exoplanets) has focused on looking for volatiles.researchers used ancient diamonds as a time capsule to study the conditions deep inside the Earth's mantle in the distant past. Moreover, studies of the gases trapped in these diamonds show that the volatile composition of the mantle has not changed much over the last 2.7 billion years.
"Studying the composition of the Earth's modern mantle is relatively simple. On average, the mantle layer begins around 30 km below the Earth's surface, and so we can collect samples thrown up by volcanoes and study the fluids and gases trapped inside. However, the constant churning of the Earth's crust via plate tectonics means that older samples have mostly been destroyed. Diamonds, however, are comparatively indestructible, they're ideal time capsules", lead researcher Michael Broadley from the University of Lorraine, France told the media.
The team also measured the isotopes of helium, neon, and argon and found that they were present in similar proportions to those currently found in the upper mantle.
"We managed to study diamonds trapped in 2.7-billion-year-old highly preserved rock from Wawa, on Lake Superior in Canada. This means that the diamonds are at least as old as the rocks they are found in — probably older. It's difficult to date diamonds, so this gave us a lucky opportunity to be sure of the minimum age. These diamonds are incredibly rare, and are not like the beautiful gems we think of when we think of diamonds. We heated them to over 2,000 C to transform them into graphite, which then released tiny quantities of gas for measurement", Broadley added.