EDMONTON — A University of Alberta study of “superdeep” diamonds reveals new knowledge about the formation of Earth’s ancient supercontinent Gondwana — offering scientists a glimpse into the evolution of deep plate tectonics.
The research, led by former Banting postdoctoral scholar Suzette Timmerman, maps the rise of rocks containing superdeep diamonds within the Earth’s mantle — the largest solid layer between the core and crust — to the base of Gondwana by examining tiny radioactive particles found in the diamonds to date the formation of the precious stones.
The age of the studied superdeep diamonds at the base of Gondwana between 650 million and 450 million years ago provides researchers with previously unknown information about when such diamonds form and how they ascended, becoming integrated into the continental base.
“Diamonds are one of the most fascinating research materials because diamonds are chemically inert,” says Timmerman. “There is basically no exchange between the surroundings and what is inside the diamonds. They are perfect time capsules.”
The study unraveled the history of these diamonds, revealing that they were transported to the base of Gondwana by host rocks, which carried subducted mantle material. These rocks, contributed to the growth of Gondwana from below. Approximately 90 million years ago, violent volcanic eruptions brought these diamonds to the Earth's surface, primarily in the continental fragments of Brazil and Western Africa, both integral parts of Gondwana.
By examining these superdeep diamonds and their inclusions, scientists can infer that the diamonds traveled with various segments of the ancient supercontinent as it eventually dispersed to form our present-day continents.
Timmerman and co-author Graham Pearson say there are still a lot of unknowns when it comes to deep plate tectonic cycles because it is so difficult to get samples from Earth’s mantle.
“Even minute amounts of material can give us really important information,” says Timmerman.
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