While it is known that for diamonds to form there needs to be carbon deep in the Earth, and for these diamonds to turn pink they must be subjected to forces from colliding tectonic plates, Curtin University researchers have found the third ingredient needed for the presence of pink diamonds at surface level, which is continents that were ‘stretched’ during continental break-up approximately 1.3 billion years ago.
“The vast majority of primary economic diamond deposits are hosted in kimberlite diatremes located in Archean cratons, with characteristically old and thick continental lithosphere thought to be necessary for sustained diamond growth,” said Curtin University researcher Hugo Olierook and his colleagues.
“However, the largest source of natural diamonds discovered to date, the Argyle mine in the Kimberley region of Western Australia, is one of only a few economic deposits found within a Paleoproterozoic orogen adjacent to cratonic regions underlain by Archean basement.”
“Moreover, Argyle is hosted in olivine lamproite, rather than kimberlite, and has yielded over 90% of all pink diamonds discovered,” they added.
“The discovery of Argyle in 1979 resulted in a paradigm shift that led to diamond exploration in non-Archean terranes.”
“Despite its importance, the geodynamic drivers responsible for the emplacement of such an unusual diamond-bearing complex remain unclear.”
By using laser beams smaller than the width of a human hair on Argyle rocks, Dr. Olierook and co-authors found Argyle to be 1.3 billion years old, which is 100 million years older than previously thought.
“Argyle is located at the point where the Kimberley region and the rest of northern Australia smashed together many years prior, and that sort of collision creates a damaged area or ‘scar’ in the land that will never fully heal,” Dr. Olierook said.
“While the continent that would become Australia didn’t break up, the area where Argyle is situated was…
Read the full article here