Title: New Research Reveals How Diamonds Make Their Way to the Surface, Offering Clues for Diamond Exploration
Subtitle: The Breakup of Earth’s Tectonic Plates Holds the Key to Diamond Formation and Deposits
Date: July 29, 2023
Researchers from various countries have made groundbreaking discoveries regarding the origin and journey of diamonds from deep within the Earth to the surface. Their findings, published in the journal Nature, suggest that diamonds are not only a symbol of eternal commitment but also a sign of Earth’s tectonic plate breakup. Moreover, the research may provide valuable clues for locating new diamond deposits.
Diamonds, known for being the hardest naturally-occurring stones, require extreme pressures and temperatures to form deep within the Earth. The researchers aimed to understand how diamonds make their way to the surface. They discovered that diamonds are carried up in molten rocks called kimberlites, which are created through explosive eruptions.
The relationship between diamond eruptions and the supercontinent cycle, a pattern of landmass formation and fragmentation in Earth’s history, has been a subject of debate among geologists. Two theories have emerged to explain kimberlite eruptions: one involving the stretching and splitting of the Earth’s crust, and the other involving mantle plumes.
However, existing theories faced challenges in explaining the mechanisms behind kimberlite eruptions. The strength and stability of the main part of the tectonic plate, known as the lithosphere, posed difficulties for fractures to penetrate. Additionally, many kimberlites lacked the expected chemical characteristics associated with mantle plumes.
To address these limitations, the researchers utilized statistical analysis, including machine learning, to examine the link between continental breakup and kimberlite volcanism. They found that most kimberlite eruptions occurred 20 to 30 million years after the tectonic breakup of Earth’s continents. Furthermore, regional studies focusing on Africa, South America, and North America supported this finding, revealing a gradual migration of kimberlite eruptions from continental edges to interiors at a uniform rate.
The researchers proposed a new mechanism called the domino effect, explaining how continental breakup leads to kimberlite magma formation. During the process of rifting, a small region of the continental root sinks into the underlying mantle, triggering edge-driven convection. This convection sets off a chain of flow patterns beneath nearby continents, which removes a significant amount of rock from the base of the continental plate.
Computer models demonstrated that this process creates the ideal conditions for melting and generating gas-rich kimberlites. The buoyancy provided by carbon dioxide and water enables the magma to rapidly rise to the surface, carrying diamonds along with it.
Importantly, this new model does not contradict the association between kimberlites and mantle plumes. Rather, it complements existing theories by emphasizing the systematic patterns observed in kimberlite-rich regions. By understanding the spatial, time-based, and chemical patterns of kimberlite eruptions, researchers hope to identify the possible locations and timings of past volcanic eruptions, aiding in the discovery of diamond deposits and other rare elements necessary for the green energy transition.
As the search for new diamond deposits continues, it is crucial to consider ethical concerns. Campaigns against conflict diamonds and mines with poor working conditions are ongoing, with efforts to eliminate these diamonds from world markets.
The research sheds light on the formation of diamonds throughout Earth’s history, emphasizing that although diamonds may not be forever, new ones have been repeatedly created over long periods. The findings open up exciting possibilities for diamond exploration and provide insights into Earth’s geological processes.
Reference:
Thomas M. Gernon et al, “Rift-induced disruption of cratonic keels drives kimberlite volcanism,” Nature (2023). DOI: 10.1038/s41586-023-06193-3.