An international team of scientists from China and Australia has uncovered a remarkable connection between diamond formation and the stability of ancient continental platforms known as cratons. Their research, published in Science Advances, reveals how carbon from subducting oceanic plates influences geological processes in Earth’s mantle, reshaping our understanding of continental evolution.

How Does Carbon Affect Cratons?

Researchers from the Guangzhou Institute of Geochemistry, in collaboration with colleagues, conducted experiments simulating conditions in Earth’s upper mantle. They found that carbonate melts from oceanic plates behave differently depending on temperature:

  • In cold conditions (at depths of 250–660 km beneath cratons), these melts are reduced, transforming into diamonds. This strengthens the roots of ancient continental platforms, making them resistant to destruction for billions of years.
  • In hot mantle plumes, the same melts oxidize surrounding rocks, weakening the lithosphere. This can cause surface uplift and volcanic activity, leading to craton destruction.

“Our discovery explains why some cratons remain stable for billions of years, while others are destroyed by mantle processes,” said Professor Yu Wang, the study’s lead author.

Diamonds as Indicators

Comparing laboratory samples with natural diamonds from Africa and South America confirmed that their chemical composition reflects the conditions under which they formed. Diamonds created in cold, reductive environments serve as markers of craton stability, while oxidative processes signal their destruction. This finding enables scientists to more accurately date diamond formation and predict the stability of continental platforms against tectonic changes.

Scientific Significance

The study highlights the critical role of carbon in the global cycle between Earth’s surface and its interior. It sheds light on how ancient continents formed and why some have persisted to the present day while others vanished. Additionally, the findings enhance the ability to predict tectonic activity and locate diamond deposits associated with cratons.

Research Prospects

The discovery paves the way for further exploration of mantle processes and their impact on Earth’s evolution. Scientists plan to use the data to develop more accurate models of the global carbon cycle and analyze the geological history of continents. This could also aid in the search for new diamond deposits, which are often linked to ancient cratons.