GEOGRAPHY

Pink diamond Tibetan ancient continent cracking clues


The Argyle region of Western Australia is one of the world’s largest sources of natural diamonds and the largest source of fancy color diamonds. Australian scientists have found that the formation of the region may be related to the fragmentation of the earliest supercontinents about 1.3 billion years ago. The study was published September 19 in Nature Communications. Studies have shown that the junctions of the continents may be important for the discovery of pink diamonds or may be useful for the exploration of other diamond mines.

Prior to its closure in 2020, the Argyle Diamond Mine produced more than 90% of the pink diamonds found to date. Most diamond deposits and mines are located deep in the Earth’s volcanic rocks, which rapidly transfer diamonds from the Earth’s deep interior to the surface of the middle of the ancient continent, which is more than 2.5 billion years old.

Unusually, the Argyle deposit is located in young rocks that once sat at the junction of two paleocontinents, the Halls Creek orogenic belt, which is an important factor in the production of pink diamonds. The formation of red, brown and pink diamonds requires enormous pressure from continental collisions to distort their lattice and give color to the fore.

Scientists speculate that such an event occurred in Argyle more than 1.8 billion years ago, when Western Australia and Northern Australia collided and turned colorless diamonds hundreds of kilometers deep into pink diamonds. However, the reasons for bringing these diamonds to the surface remain unclear.

Hugo Olierorook of Curtin University and colleagues analysed minerals mined from the Argyle deposit and found that the deposit was brought to the surface earlier than previously thought, overlapping with the cracking time of the first supercontinent Nuna. They point out that the cleavage of Nuna could reopen the ancient junctions left by the colliding continents. Molten inclusions containing diamonds may have crossed this continental junction to form this vast diamond deposit.

Researchers believe that diamond formation during supercontinental cracking may be common, but such phenomena in the periphery rift zone of the paleocontinental massif have been overlooked. The results have improved understanding of the mechanisms by which the Argyle deposit was formed and the processes that occur deep into the Earth.

A selection of faceted fancy color diamonds from the Argyle Diamond Mine. Photo by Murray Rayner

View of the Argyle diamond mine in the Kimberley region of Western Australia. Image courtesy of Murray Rayner

(Source: Feng Weiwei, China Science News)

Related paper information:https://doi.org/10.1038/s41467-023-40904-8



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