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Characterisation, origin and emplacement of diamond-bearing ultramafic rocks in non-traditional (off-craton) settings

Final Activity Report Summary - HUTDIAM (Characterisation, origin and emplacement of diamond-bearing ultramafic rocks in non-traditional (off-craton) settings)

Dates in geological time when volcanoes brought diamonds to the surface at locations of South and West Greenland were determined using the results of measurements on the mineral perovskite. In South Greenland, these events occurred in the late Jurassic period, about 150 million years ago, whereas in West Greenland the diamond-carrying volcanic rocks, called kimberlites, were much older with respective eruptions having occurred in the early Cambrian period about 570 million years ago.

In the West Greenland case, the diamonds were large enough to allow for efficient measurements to determine their age. In this case, the oldest diamonds resided deep in the Earth for approximately 40 million years before being brought to the surface. This diamond formation age, at about 610 million years ago corresponded well with the eruption of a nearby and unusual type of volcano called a carbonatite which other researchers have dated at 600 million years ago.

Scientists and industry workers often ignored carbonatites when looking for diamonds as they were thought to form at depths too shallow for diamonds to be stable. Results from this project showed that not only the ages of diamonds but the compositions of their associated kimberlites and the locations on the surface where they occurred were closely associated with these unusual carbonatitic rocks. The results of the project should assist diamond explorers in looking for specific ages and compositions of rocks in their search for diamonds in West Greenland and subsequently in other diamondiferous regions worldwide.