New study sheds light on a fundamental mechanism for healing Earth’s continental plates, with implications for diamond exploration and the location of economically important minerals.
“Cratons are the oldest stable land masses on Earth and are widely known as deposits of economically important diamonds and metals,” said Jingao Liu, senior author and visiting researcher at the Department of Earth and Earth Sciences. atmosphere of the University of Alberta. “Disturbances to the lithosphere beneath these cratons can be critical in harboring world-class mineral deposits, especially diamonds and precious metals like platinum.”
Cratons have survived billions of years being dragged around the Earth by the movement of tectonic plates, undergoing a complex geological life cycle of thinning and healing. This is the first study that provides evidence for the mechanism that heals the lithosphere beneath the cratons and creates the conditions for the formation of valuable minerals, Liu said.
“We found direct evidence that the deep mantle root was replaced around 1.3 billion years ago,” said Liu, visiting professor at the Chinese University of Geosciences (Beijing), who completed the research with his collaborator Graham Pearson, recipient of the Canada Excellence Research Chair and the Henry Marshall Tory Chair in the Department of Earth and Atmospheric Sciences.
“This replacement of an ancient deep continental root coincides with the appearance of a giant outpouring of basalt magma in this region – known as the Great Mackenzie Igneous Event, one of the most significant in the history of the Earth, ”Pearson said. “This event produced key targets for nickel and platinum metallic mineralization in the Canadian Arctic, and we are only beginning to understand its importance for both destruction and diamond formation – the former via the removal of the old root and the second by creating a new thick lithosphere. root.”
Researchers examined samples that erupted from diamondiferous kimberlite in the Canadian Arctic, east of Kugluktuk in Nunavut, to better understand this process. Using simulations based on field findings, the team showed that the remnants of this geological melting process were redeposited in the mantle, re-thickening the lithosphere and showing the first strong evidence for the mechanism behind the healing. from a continental root.
“Beyond improving our understanding of the mechanism behind recratonization, these findings also have economic significance,” Liu explained. “We can map the affected mantle root area that could host mineral deposits related to this event, including areas where diamonds may be present.”
The research was supported by the Geo-mapping program for energy and minerals by the Geological Survey of Canada (GSC).
“These programs are of great help to academics and industry,” Liu said. “This work required us to build a scientifically very diverse team of researchers, including experts in geochemistry, geophysics and digital geodynamic modeling.
In addition to funding, the GSC also provided research support, including the work of co-author and seismologist Andrew Schaeffer.
“To demonstrate that what we once thought to be ancient, unchanged cratons are in fact substantially reworked is a major discovery. This implies that there is the potential for many other cratonic regions to have been altered in the same way, given the correct circumstances, ”Schaeffer said. “In addition, studies like this are critically important because they combine several facets of geoscience to make a much more robust interpretation.”
The research is part of a major collaborative program between the U of A and the China University of Geosciences (Beijing).
“This collaboration serves to explore the origins and evolution of the deep roots of continents and their implications for creating the mineral deposits that humanity needs,” said Liu. “Our goal is to continue to better understand how these recratonization events concentrate precious metals in the earth’s crust and where to look for new diamond deposits.”
The study, “Recratonization by plume of the deep continental lithospheric mantle», Was published in Nature.
| By Andrew Lyle for Troy Media
This article was submitted by the University of Alberta Folio online magazine. The University of Alberta is an editorial content partner of Troy Media.
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