One of the most crucial processes that make our planet suitable for life is its carbon cycle, which maintains and regulates the concentration of carbon on the planet. Of the many steps in the carbon cycle, in one step, an amount of carbon reaches the interior of our planet. This happens during tectonic plate subduction when tectonic plates converge below the earth’s surface into the mantle, resulting from their collision. Scientists believed that the amount of carbon drawn into the mantle is mostly thrown out of volcanic eruptions balancing the carbon cycle. Now, a new study by scientists from Cambridge University and Nanyang Technological University Singapore has found that only one-third of the carbon drawn into the mantle is returned above the surface through volcanic chains. The remaining carbon, undergoing the extreme temperatures in the mantle, may eventually become diamond.
The team of researchers replicated the high-pressure and temperature zones similar to those in subduction zones and conducted various experiments. They found that when carbonate rocks — the mineral form of carbon — are drawn to the mantle, they lose Calcium and enrich themselves with Magnesium. This change in combination makes them less soluble, which in turn, keeps them from flowing into the volcanic liquid and getting spewed out. Instead, the carbonate sinks further into the mantle where it could be transformed into diamond.
Though the study supports the growing evidence of the chemical transformation that happens beneath the earth’s surface, there is a lot of research required to be done in the field, scientists say. “In the future, we aim to refine our estimates by studying carbonate solubility in a wider temperature, pressure range and in several fluid compositions,” said Stefan Farsang, lead author of the research, in a statement. The study was published on July 14 in Nature Communications.
According to scientists, studying this process can help scientists understand processes that lock carbon inside the earth, which scientists could accelerate in search of a way to solve the climate crisis as well. Currently, the global average of carbon dioxide in the atmosphere is about 416 parts per million, which is much higher compared to an ideal concentration of 280 to 300 ppm.