Kimberlite: The Key To Understanding Diamond Volcanism

Diamonds are precious gems that have fascinated humans for centuries. They are formed under high pressure and temperature deep in the Earth's mantle, and are brought to the surface by rare and explosive volcanic eruptions.

These eruptions produce a type of rock called kimberlite, which contains diamonds and other minerals. Kimberlites are found in the oldest and most stable parts of continents, such as South Africa, Canada, and Australia.

A new study by an international team of scientists has cracked the code of what causes diamonds to erupt, and revealed a surprising link between tectonic plate movements and diamond formation.

Tectonic plate breakup triggers diamond eruptions

(Photo : ALEXANDER NEMENOV/AFP via Getty Images)

The study found that the main driving force behind diamond eruptions is the breakup of tectonic plates, as per Phys.org.

Tectonic plates are large pieces of the Earth's crust that move and interact with each other over time.

Sometimes, tectonic plates split apart, creating rifts or cracks in the crust. This process is called continental rifting, and it leads to the formation of new ocean basins.

The researchers discovered that most kimberlite eruptions occurred 20 to 30 million years after continental rifting.

They also found that kimberlite eruptions tended to migrate from the edges to the interiors of continents over time, at rates that were consistent across different continents.

These findings suggested that continental rifting had a long-lasting and far-reaching impact on the Earth's mantle, which is the layer between the crust and the core.

Also Read: Earth Is Full Of Diamonds: A Quadrillion Tons In Fact

Continental rifting disrupts the Earth's mantle and creates diamond-rich magmas

The researchers proposed a domino effect model to explain how continental rifting causes diamond eruptions, as per Queen's University.

This theory proposes that when tectonic plates separate, they leave voids or gaps in the crust. These spaces are filled by rising hot material from the deeper mantle.

This process is called mantle upwelling, and it creates zones of high temperature and low pressure in the mantle.

Mantle upwelling also affects the surrounding regions of the mantle, creating waves or pulses of pressure and temperature changes that propagate through the mantle over millions of years.

Due to the extreme pressure and cold temperature at these depths, diamonds are stable. Diamonds can become unstable and melt as these waves pass by because they can change the temperature or reduce pressure in certain regions.

When diamonds melt, they form carbon-rich magmas that can rise up through cracks or weaknesses in the crust.

These magmas can also incorporate other minerals from the mantle or crust along their way. When these magmas reach shallow depths, they erupt explosively as kimberlites, bringing diamonds and other minerals to the surface.

Implications for diamond exploration

The study has important implications for diamond exploration and conservation. It provides a new predictive tool to locate potential diamond deposits based on tectonic plate history and mantle dynamics, as per Environment GO!.

It also reveals new insights into how diamonds form and evolve in the Earth's mantle over geological time scales.

Mining diamonds can have negative impacts on the environment and society, such as deforestation, soil erosion, water contamination, human rights violations, or violence.

Pollution can degrade the quality or color of diamonds, making them less desirable or valuable. Conflict can fuel or fund wars or corruption using diamonds as a source of income or power.

Climate change can alter the conditions or processes that create or preserve diamonds in the Earth's mantle or crust. Therefore, it is essential to protect and conserve diamonds for their natural and cultural heritage.

Related Article: How Diamonds Are Helping Geologists Understand Superdeep Earthquakes