Faceted fancy-color diamond from the Argyll diamond mine. Image source: Maury Rayner/"Nature Communications"
The Argyle region of Western Australia is one of the world's largest origins of natural diamonds and the largest origin of colored diamonds. The formation of this region may be related to the breakup of the earliest supercontinent about 1.3 billion years ago. The research results were published in "Nature Communications" on the 19th, showing that the junction of continents is important for the discovery of diamonds and is helpful for the exploration of new diamond mines.
Before closing in 2020, the Argyle Diamond Mine produced more than 90% of the pink diamonds discovered to date. Most diamond deposits and mines are located in volcanic rocks deep within the Earth, which rapidly transported diamonds from the Earth's deep interior to the surface in the middle of ancient continents that are more than 2.5 billion years old. Unusually, the Argyle deposit is located in young rocks that were once located at the junction of two ancient continents (the Halls Creek orogen), which is an important factor in the production of pink diamonds. The formation of red, brown and pink diamonds requires tremendous pressure from continental collisions to distort their crystal lattice and allow the color to appear. Such an event occurred in Argyll more than 1.8 billion years ago, when a collision between Western Australia and Northern Australia turned otherwise colorless diamonds hundreds of kilometers deep into pink diamonds. However, what brought these diamonds to the surface remains unclear.
A team of researchers from Australia's Curtin University analyzed minerals mined from the Argyle deposit and found that the deposit was brought to the surface earlier than previously thought, overlapping with the breakup of the first supercontinent Nuna. The team noted that Nuna's breakup could reopen ancient junctions left by colliding continents. Diamond-bearing molten inclusions may have crossed this continental juncture to form this massive diamond deposit.
The research team believes that the formation of diamonds during the breakup of supercontinents may be a common phenomenon, but this phenomenon in rift zones at the edges of ancient continental blocks has been ignored. The results improve understanding of how the Argyle deposit formed and the various processes that occur deep in the Earth.
